A polarographic study of methionine complexes of cadmium and indium

The stability constants of methionine complexes of cadmium were determined polarographically by ths method of DeFord and Hume as β₁ =6·5 × 10³, β₂ = 1·7 × 10⁶ and β₃ = 2·1 · 10⁸. The indium complexes were studied by the modified method of Momoki and Ogawa and two complexes, with β₁ = 1·7 × 10⁸ and β₂ = 8·4 × 10¹³, were identified in the concentration range studied. The haf-wave potential of uncomplexed indium ion which cannot be measured directly owing to the irreversible nature of the reduction was calculated as — 0·503 Vvs. SCE.     

Spectrophotometric studies of copper (II)—bis-2-pyridyl glycol complex

An aqueous solution ofbis-2-pyridyl glycol forms a deep blue water-soluble complex with an aqueous solution of copper (II) salts. The complex has an absorption maximum at 600–650 mµ between pH range 3·0–8·7. The complex is stable for four days and obeys Lambert-Beer’s law in the concentration range of 5·08–50·80 ppm. of copper (II) in solution. The optical density of the complex remains constant between pH 3·8–5·9. The molar composition as determined by the method of continuous variation and by the slope ratio method has been found to be 1:1. The limits of interference due to some foreign ions during the estimation of copper (II) have been determined.     

A polarographic study of methionine complexes of cadmium in mixed solvents

Methionine complexes of cadmium in 25 and 50 per cent aqueous mixtures of ethyl and methyl alcohol and dioxan have been studied. The half-wave potentials measured in both the alcohols were the same and the reduction was reversible. Three complex species withβ ₁=1·0×10⁴,β ₂=1·1×10⁷ andβ ₃=1·2×10⁹ were found in 25 per cent alcohol while four complexes withβ ₁=3·0×10⁴,β ₂=4·3×10⁷,β ₃=4·0×10⁹ andβ ₄=1·6×10¹¹ were observed in 50 per cent solutions. In the case of dioxan, the reduction was quasi-reversible (k _s=1·0×10^?3 cm sec^?1) in 25 per cent and irreversible (k _s=2·0×10^?4 cm sec^?1) in 50 per cent solutions. The stability constants, evaluated using the formal potentials, wereβ ₁=7·0×10³,β ₂-3·9×10⁵;β ₂=3·9×10⁸ andβ ₄=3·4×10¹⁰ in 25 per cent dioxan andβ ₁=1·5×10⁴,β ₂=3·4×10⁷.β ₃=7·5×10⁹ andβ ₄=9·0×10¹¹ in 50 per cent solutions.     

Complex formation between cadmium and thiosalicylic acid

Polarographic measurements on the system Cd-thiosalicylic acid (TSA) reveal the formation of a complex, 1:2:: metal: ligand (ammonia buffer pH 9·1,µ=0·2 M, 50% alcoholic medium), dissociation constant of the complex being 6·3 × 10^?8 at 30° C. Potentiometric titrations confirmed this stoichiometry, stepwise stability constants, logk ₁ and logk ₂ being 7·85 and 8·10 respectively. The complex has also been isolated and studied in solid state.     

Periodicities in the series of cyclonic disturbances over India

The time series of yearly occurrence frequency of cyclonic disturbances over the Indian region for 1891–1970 is subjected to power spectrum analysis by the maximum entropy method (MEM) of Burg. Earlier analyses by the conventional Blackman-Tukey method had indicated periodicities atT= 2·3-2·5, 5 and 30–45 years at about 90–95% significance level. The present analysis shows peaks atT = 1·2, 2·4, 2·9, 3·7, 4·7, 6·4, 7·4, 9·2, 10·5, 20 and 40–60 years but the significance level may not be better than the earlier method. When data are analysed separately for first half and latter half, periodicities observed are quite different, the earlier half revealingT= 1· 2, 2·3, 2·9, 4·7, 9·0 and 23 years and the latter half revealingT= 1·2, 2·1, 2·4, 3·8, 6·7 and 21 years. Thus, a change of pattern before and after about 1920 is indicated. However, the power in the various peaks is small and a random origin cannot be ruled out. An analysis of several artificially produced samples of pseudo-Gaussian random white noise of the same mean, standard deviation and length (80 values) as the above physical samples indicated that similar peaks could occur by pure chance also. Physically, T=l·2 years corresponds to the Chandler’s wobble and other peaks could be harmonics of the sunspot cycleT= 11 years or double sunspot cycleT = 22 years. However, no peak is noticed at or nearT= 11 years whereasT near 22 years is noticed.     

Amperometric determination of copper with resacetophenone-phenylhydrazone

An amperometric method for determination of copper (II) with resacetophenone-phenylhydrazone is described. The method is useful to determine the metal in amounts ranging from 1·0–16·0 mg with an accuracy of ±1 per cent. Ten-fold excess of zinc, cadmium and nickel did not interfere. Iron which interefered both polarographically and chemically was complexed with sodium fluoride and the determination was successfully carried out. The method was applied for the determination of the metal in german silver.     

Ratio of pions to protons and ratio of neutral to charged interacting particles at mountain altitude of 800 gm/cm2

Using a combined set-up of a multiplate cloud chamber, an air Cerenkov counter and a total absorption spectrometer, the ratio of pions to protons not associated with large air showers has been determined to be 0·50 ± ·07 in the energy region 20–40 GeV at an altitude of 800 gm/cm². In the same energy region the ratio of neutral to charged particles is found to be 0·66 ± ·07. From the ratio of neutrons to protons deduced from these measurements (i.e., 0·99 ± ·11), it is concluded that most of the charge excess of nuclear active particles of energies > 20 GeV at mountain altitudes and sea-level is due to pions.     

Spectrophotometric studies of uranium (VI)-pongamol complex

The spectrophotometric studies of uranium (VI)-pongamol complex have been carried out in 50% aqueous ethanolic solutions. Pongamol produces a yellow complex with an aqueous uranyl salt solution, the complex is soluble in 50% aqueous ethanol. The complex is quite stable for 24 hours, the optical density remaining constant at pH 5·6–7·1. The complex obeys Beer-Lambert’s law at 390 mµ in the concentration range of 1 to 5 p.p.m. of uranium in solution. The molar composition of the pongamol uranium (VI) complex has been found to be 2:1, and its tentative structure has been suggested. The cations and anions which interfere in the estimation of uranium using pongamol have been indicated.     

Chalcones as inorganic analytical reagents

1·0–6·0 p.p.m. of germanium could be estimated spectrophoto-metrically with 2′, 3′, 4′-trihydroxy chalcone as reagent at pH 5·8–6·0. The complex was shown to contain three gram-moles of the reagent to one gram-atom of germanium both by Job’s method of continuous variations and the slope ratio method of Harvey and Manning. The instability constant was determined by the method of Edmonds and Birnbaum and found to be 1·670×10^?11 at 28° C. It is concluded that complex formation involved only the two ortho hydroxyls in each molecule of the reagent and the carbonyl group played no part.     

Investigations on the multiply charged nuclei of the primary cosmic radiation near the geomagnetic equator using nuclear emulsion

A nuclear emulsion stack was exposed over Hyderabad, India (geomagnetic latitudeλ=7·6° N) under a mean atmospheric depth of 6·8 g./cm.², on 24 March 1960. The relative and absolute intensities of Be and B nuclei and nuclei of charge Z?6 (the S-nuclei) have been determined in this stack. The intensities were extrapolated to the top of the atmosphere using measured fragmentation parameters involved in collisions of cosmic ray nuclei in graphite. The flux values of Be, B and S nuclei at the top of the atmosphere have been determined to be 0·025±0·011, 0·101±0·023 and 1·12±0·10 particles/m.² sec. sr. respectively. The ratios of intensities B/S, Be/S and Be/B have been found to be 0·09±0·02, 0·022±0·008 and 0·25±0·11 respectively. These ratios of intensities have been used (a) to compute the amount of matter traversed by the radiation before reaching the vicinity of the earth as 2·6±0·6 g./cm.², (b) to show that the Fermi mechanism of acceleration of particles is not efficient at these energies (1–10 GeV/n.) in interstellar space and (c) to show that preferential acceleration of H₁-nuclei (Z?20) is not of overwhelming importance. The derived source composition of nuclei of energy ?7·5 GeV/n suggests that N, O, F and H₃-nuclei (Z=10–15) have similar abundances in the universe and in cosmic rays, and that C and H₁-nuclei are overabundant in cosmic rays.     

Determination of lead by the precipitation of lead molybdate from a homogeneous solution by the diffusion method

A satisfactory quantitative method for the determination of lead as lead molybdate by precipitation from a homogeneous solution has been developed. The method employs the diffusion of ammonia into a solution containing lead and sodium molybdate in nitric acid medium. The precipitation of lead in the range of 28·0–280·0 mg is complete within 8–9 hours. Anions like sulphate, arsenate, phosphate, tungstate and chromate in moderate concentrations and cations such as Zn (II), Cu (II), Ni (II), Co (II), Mn (II), Cd (II), Hg (II), Ag (I), Ti (IV), As (V), Mg (II) and Al (III) do not contaminate the precipitate. The precipitate gets constant weight at 120°. This eliminated the ignition of the precipitate,i.e., the contamination of molybdic oxide by the precipitate was reduced.     

Spectrophotometric studies of 6-methyl pyridine-2-aldoxime-iron (II) complex

6-Methyl pyridine-2-aldoxime produces with iron (II) solution a deep red complex soluble in 50% (by volume) aqueous acetone. The complex is stable at 10–45°C. and its colour intensity does not vary between pH 7·3 and 10·0. The complex obeys Lambert-Beer’s law at 520 mµ in the concentration range of 1·12 to 28·0 p.p.m. of iron.     

Synergism in the extraction of cadmium

Synergism in the extraction of cadmium by mixtures of BFA and TOPO or TBP has been investigated. Extraction of cadmium was found negligible in the presence of BFA, TOPO or TBP alone while the addition of alkylphosphorus ester to the β-diketone resulted in considerable enhancement of the extraction. The nature of the adduct was found to be of the type [Gd (BFA)₂ (TOPO)₂] and the equilibrium constant for the reaction was also evaluated. Similar results were observed in the case of TBP, while DPSO did not enhance the extraction, indicating the donor strengths of the synergists to be in the order TOPO >TBP >DPSO. The coordination of alkylphosphate to the metal ion was confirmed by infrared spectra of the complexes in benzene.     

He3 nuclei in the low energy primary cosmic radiation

The flux of He³ nuclei and the ratio He³/(He³+He⁴) in the low energy primary cosmic radiation have been determined using a stack of nuclear emulsions exposed at 3·1 g. cm.^?2 of atmospheric depth from Fort Churchill, Canada, in June 1963. The grain-densityversus residual range method was used to determine the masses of the helium nuclei. Using a sample of 146 helium nuclei whose masses could be identified, the ratio He³/(He³+He⁴) is obtained as 0·14±0·04 for the kinetic energy interval 115–210 MeV per nucleon and 0·43±0·11 for the rigidity interval 0·85–1·05 BV. The differential fluxes of He³ nuclei are determined as 0·017±0·006, 0·045±0·015, and 0·054±0·017 particles/M². Sr. Sec. MeV/nucleon, in the kinetic energy intervals of 117–183, 183–217, and 217–250 MeV/nucleon respectively. These results are compared with those of other investigators. From the results of the present work the amount of matter traversed in space by the primary cosmic ray helium nuclei of energy 115–210 MeV/nucleon is obtained as 4·7±1·8 gm. cm.^?2 of hydrogen.     

Markov chain Monte Carlo Using an Approximation

This article presents a method for generating samples from an unnormalized posterior distribution f(·) using Markov chain Monte Carlo (MCMC) in which the evaluation of f(·) is very difficult or computationally demanding. Commonly, a less computationally demanding, perhaps local, approximation to f(·) is available, say f^**_x(·). An algorithm is proposed to generate an MCMC that uses such an approximation to calculate acceptance probabilities at each step of a modified Metropolis–Hastings algorithm. Once a proposal is accepted using the approximation, f(·) is calculated with full precision ensuring convergence to the desired distribution. We give sufficient conditions for the algorithm to converge to f(·) and give both theoretical and practical justifications for its usage. Typical applications are in inverse problems using physical data models where computing time is dominated by complex model simulation. We outline Bayesian inference and computing for inverse problems. A stylized example is given of recovering resistor values in a network from electrical measurements made at the boundary. Although this inverse problem has appeared in studies of underground reservoirs, it has primarily been chosen for pedagogical value because model simulation has precisely the same computational structure as a finite element method solution of the complete electrode model used in conductivity imaging, or “electrical impedance tomography.” This example shows a dramatic decrease in CPU time, compared to a standard Metropolis–Hastings algorithm.     

Isotropic background cosmic X-rays in the energy range 50–290 KeV

The observations of omnidirectional X-ray flux at the top of the atmosphere have been extended upto 200 KeV using a balloon-borne NaI (Tl) scintillator detector at Hyderabad, India. The omnidirectional flux at 60 KeV is found to be 0·0066±0·0014 photons/cm.² sec. ster. KeV. The X-ray flux in the energy range 50–290 KeV can be adequately represented by the spectrum Ke^?2.2±0.4. New upper limits to the hard X-ray flux from the quiet sun have also been obtained from the same measurement.     

Spectrophotometric investigation of beryllium-2-hydroxy chalcone complex

2′-Hydroxy chalcone gave an intense orange-yellow color with beryllium in the pH range 5·5–6·2. The limits of identification and dilution were 0·125γ and 1:4 × 10⁵ respectively. A detailed spectro-photometric investigation of the color reaction was carried out. The complex obeyed Beer’s Law in the concentration range of 0·5–6·0p.p.m. at 460 nm. In the complex the ratio of metal to ligand is 1:2. The instability constant of the complex was 2·176 × 10^?6 at 28°. Oxalate, tartrate, citrate and fluoride interfered. The tolerance limits of iron, aluminium, chromium, uranium, thorium and vanadium are reported.     

Estimation of the quality of adhesion of a metallic coating to a polymer film using the scratch method

A method of determining the quality of adhesion of a metallic coating to a polymer film at coating thicknesses of 1000–3000 Å and film thicknesses of 10–100 µ using the scratch method is described. The results of testing various aluminized polyethylene terephthalate and polyethylene film specimens, differing with respect to the treatment of the polymer surface before deposition of the metal, are presented. The aluminization vacuum was 5 · 10^?4 or 9 · 10^?3 mm Hg.     

Modeling cadmium accumulation in radish,carrot, spinach and cabbage

Heavy metals like cadmium and arsenic have serious health consequences and ecosystem impacts. Due to various factors including the disposal of municipal and industrial wastes, application of fertilizers, atmospheric deposition and discharge of wastewater on land, has resulted in increase in the concentration of heavy metals in the soil. Crops and vegetables grown on such soil accumulate heavy metals, which leads to phyto-toxicity. For understanding and managing precious natural resources, mathematical models are increasingly being used. This paper describes a dynamic macroscopic numerical model for heavy metal transport and its uptake by vegetables in the root zone. The model is applied for simulating cadmium uptake by radish (Raphanus sativus), carrot (Daucos carota), spinach (Spinacia oleracea) and cabbage (Brassica oleracea) by using measured field data. The governing non-linear partial differential equations are solved numerically by an implicit finite difference method using Picard’s iterative technique and the source code is written in MATLAB.     

Study of microwave absorption and molecular structure of some substituted naphthalene sulphonic acids and their dipolar mixture

The dielectric constant (∈′) and the loss factor (∈″) of naphthalene sulphonic acid, 0-naphthol sulphonic acid, l-naphthylamine 8-sulphonic acid and 2–4 dinitro naphthol 7-sulphoinc acid and their dipolar mixture in dilute solution of dioxane have been determined at three temperatures (20°, 30° and 40° C) in 3·13 cm (9585 Mc/sec.) microwave region by concentration variation method. The data obtained have been used for determining the relaxation times. The values of relaxation times at different temperatures have been used to determine free energy, heat and entropy of activation for the process of dipole orientation. It has been concluded that the dipole orientation in the molecules is contributed by both molecular as well as intra-molecular rotations. In case of dipolar mixture the relaxation time is average of the two components.