Cobalt(II)-selective membrane sensor based on a [Me2(13)dieneN4] macrocyclic cobalt complex

A new poly(vinyl chloride)-based membrane was fabricated with the cobalt(II) complex of 2,4-dimethyl-1,5,8,11-tetraazacyclotrideca-1,4-diene [Me₂(13)dieneN₄] as an ion carrier. The membrane composition was Co²⁺ complex/PVC/NaTPB/DBP 15:50:15:20 (w/w). The sensor exhibited a Nernstian response for Co²⁺ ions over a wide concentration range (7.94×10⁻⁶–1.0×10⁻¹ M) at pH 2.5–7.0, a response time of 10 s, and it could be used for 3 months without any significant divergence in potential. The proposed membrane sensor exhibited good selectivity for Co²⁺ over a wide variety of other metal ions and in mixtures containing up to 25% (v/v) non-aqueous content. The sensor was successfully used as an indicator electrode in the potentiometric titration of Co²⁺ with EDTA and the direct determination of Co²⁺ in real samples.     

Fabrication of polyindene and polyindole nanostructures

One-dimensional (1D) nanostructures of fused ring polymeric systems: polyindene (PIn) and polyindole (PInd) were fabricated onto glass substrates using a chemical vapor deposition (CVD) method. Morphology of fabricated PIn and PInd structures studied using Olympus microscope reveals formation of 1D straight tubular, smooth and fluorescent nanostructures. The results obtained were further correlated with scanning electron microscopic (SEM) studies of PIn and PInd nanostructures, indicating appearance of fine nanothread entangled network (having diameter ∼ 50 nm) for PIn, and well-defined, straight and aligned nanotubes (having diameter ∼ 60 nm) for PInd. A comparative study on the morphology/dimensions of fabricated PIn and PInd nanostructures with the nanosized PIn and PInd structures obtained by oxidative synthetic routes is also discussed. The structural composition of fabricated PIn and PInd nanostructures is confirmed by Fourier transform infrared (FTIR) spectroscopy, thereby indicating existence of all infrared markers corresponding to the characteristic bands present in PIn and PInd. The study suggests that the fabricated PIn and PInd nanodimensional structures may find potential applications in the field of nanotechnology.     

Synthesis, characterization, and antifungal activity of biaryl-based bis(1,2,3-triazoles) using click chemistry

Abstract  

Click chemistry was used to synthesize a series of biaryl-based bis(1,2,3-triazoles). Their antifungal activity was evaluated against three soil-borne plant pathogenic fungi, viz. Rhizoctonia bataticola, Sclerotium rolfsii, and Fusarium oxysporum, using the food poison technique at concentrations of 62.5–500 μg/cm³.     

Cardiac T2 measurements in patients with iron overload: a comparison of imaging parameters and analysis techniques

Measurement of cardiac T2 has emerged as an important tool to noninvasively quantify cardiac iron concentration in order to detect preclinical evidence of toxic levels and titrate chelation therapy. However, there exists variation among practitioners in cardiac T2 measurement methods. This study examines the impact of different imaging parameters and data analysis techniques on the calculated cardiac R2 (1/T2) in patients at risk for cardiac siderosis. The study group consisted of 36 patients with thalassemia syndromes who had undergone clinical magnetic resonance imaging assessment of cardiac siderosis using a standardized protocol and who were selected to yield a broad range of cardiac R2 values. Cardiac R2 measurements were performed on a 1.5-T scanner using an electrocardiogram-gated, segmented, multiecho gradient echo sequence obtained in a single breath-hold. R2 was calculated from the signal intensity versus echo time data in the ventricular septum on a single midventricular short-axis slice. There was good agreement between R2 measured with a blood suppression prepulse (black blood technique) and without (mean difference 6.0 ± 10.7 Hz). The black blood technique had superior within-study reproducibility (R2 mean difference 1.6 ± 8.6 Hz versus 2.7 ± 14.6 Hz) and better interobserver agreement (R2 mean difference 3.4 ± 8.2 Hz versus 8.3 ± 16.5 Hz). With the same minimum echo time, the use of small (1.0 ms) versus large (2.2 ms) echo spacing had minimal impact on cardiac R2 (mean difference 0.3 ± 8.7 Hz). The application of a region-of-interest-based versus a pixel-based data analysis also had little effect on cardiac R2 calculation (mean difference 8.4 ± 6.9 Hz). With black blood images, fitting the signal curve to a monoexponential decay or to a monoexponential decay with a constant offset yielded similar R2 values (mean difference 3.4 ± 8.1 Hz). In conclusion, the addition of a blood suppression prepulse for cardiac R2 measurement yields similar R2 values and improves reproducibility and interobserver agreement. The findings regarding other variations may be helpful in establishing a broadly accepted imaging and analysis technique for cardiac R2 calculation.     

Isotope fractionation by thermal diffusion in silicate melts

Isotopes fractionate in thermal gradients, but there is little quantitative understanding of this effect in complex fluids. Here we present results of experiments and molecular dynamics simulations on silicate melts. We show that isotope fractionation arises from classical mechanical effects, and that a scaling relation based on Chapman-Enskog theory predicts the behavior seen in complex fluids without arbitrary fitting parameters. The scaling analysis reveals that network forming elements (Si and O) fractionate significantly less than network modifiers (e.g., Mg, Ca, Fe, Sr, Hf, and U).     

Studies onO-Vanillinoxime as an analytical reagent

o-Vanillinoxime has now been used for the gravimetric determination of copper and nickel alone and in presence of many foreign ions. Copper can be estimated in presence of appreciable amounts of cadmium, zinc, cobalt and lead. The interference due to iron (III), antimony (III), bismuth (III) and tin (II) can be removed by suitable masking agents. Determination of copper and nickel in presence of each other has also been carried out.     

Chemistry of mixed ligand complexes of platinum: crystal and molecular structure of trans-[PtCl(CH3)(PEt3)(AsPh3)]

The dimethyl platinum(II) complex containing mixed ligands, cis-[Pt(CH₃)₂(PEt₃)(AsPh₃)] reacted with one equivalent of hydrogen chloride yielding trans-[PtCl(CH₃)(PEt₃)(AsPh₃)]. The X-ray crystal structure of the molecule shows the trans orientation of the PEt₃ and AsPh₃ ligands.     

SCORPION: A system for coincidences between recoil and projectile ions at NSC, New Delhi

An on-line facility to measure coincidences between the recoil ions and the scattered projectiles (SCORPION) has been designed, fabricated and commissioned at Nuclear Science Centre (NSC), New Delhi. The facility consists of a four jaw slit assembly, a time of flight (TOF) spectrometer, a parallel plate electrostatic charge analyser and a one dimensional position sensitive parallel plate avalanche counter (PPAC). Details of the design and working principles of various components and the test results obtained for the Si ^q+-Ar collision system are presented to highlight the performance of the system. A multiple loss of up to four electrons has been observed for 60 MeV Si⁴⁺ ions colliding with argon atoms in a single collision condition. Spectra of recoil ions detected in coincidence with a particular charge state of the scattered projectile show a bell shaped distribution as a function of the recoil charge state (r) for the electron loss events. However, the yield of recoil ions drops asr increases for the direct ionization channel. Also for electron loss, the peak of the recoil ion distribution is seen to shift to a higher recoil charge state as the number of lost electrons from the projectile increases.     

A 44 GHz HEMT amplifier

A 44-GHz amplifier using 0.25-m gate length and double-heterojunction structure HEMT devices is described. Higher gain and power performance have been obtained from the amplifier using this device at millimeter-wave frequencies. A spot gain of 9.4 dB and a 1-dB gain compression point of +7.5 dBm has been achieved at 43.5 GHz.This work was supported by the Air Force Space Division under Contract No. F04701-84-C-0113.     

Ultrasound-assisted conversion of toxic beta-asarone into nontoxic bioactive phenylpropanoid: isoacoramone, a metabolite of Piper marginatum and Acorus tararinowii

Ultrasound-assisted synthesis of bioactive isoacoramone (1), a metabolite of Piper marginatum and Acorus tararinowii, has been achieved by oxidation of toxic beta-asarone (2) with potassium permanganate/copper sulphate/alumina into asaronaldehyde (3) followed by treatment with ethylmagnesium iodide to provide 1-(2,4,5-trimethoxy)phenyl-1-propanol (4) which upon further oxidation with potassium permanganate/copper sulphate afforded 1 in 64% yield (overall 32%). Toxicological evaluation of 1 reveals it to be nontoxic up to 60 mg/kg b.w.