Synthesis of some new fluorine-containing 5-amino-1,3-disubstituted pyrazoles and 1H-pyrazolo[3,4-b]pyridines

Nine new fluorine containing 5-amino-1,3-disubstituted pyrazoles have been synthesized and characterized by spectral studies. Condensation reactions of these 5-amino-1,3-disubstituted pyrazoles with fluorinated 1,3-diketones in the presence of glacial acetic acid have been studied and the structures of the resulting 1H-pyrazolo[3,4-b]pyridines have been confirmed by ir, pmr and ¹⁹F nmr spectral studies.     

Sorption of neptunyl(V) cations on suspended silicate: Effects of pH, ionic strength, complexing anions, humic acid, and metal ions

Sorption of NpO₂ ⁺ on silicate (10.00 g/l) particles dispersed in sodium perchlorate media was studied as a function of pcH and ionic strength at 298 K. The sorption increased with increased pcH in the range of ∼6.5 to 9.2, above which saturation was observed. An increase in ionic strength from 0.20M to 1.00M (NaClO₄), increased the NpO₂ ⁺ sorption, which then decreased at 1.50M (NaClO₄) for 7<pcH<8.5. The effects of different types of ligands on the sorption of NpO₂ ⁺ to suspended silicate were investigated. The types of ligands included: (i) inorganic anions (fluoride, carbonate, phosphate (ii) N-donors (ethylenediamine, 1,10 phenanthroline (iii) carboxylic acids (oxalic acid, citric acid, iminodiacetic acid, ethylenediaminetetraacetic acid) and (iv) humic acid. A synergistic enhancement in sorption to the suspended silicate was observed for phosphate, oxalate, ethylenediaminetetraacetic acid, ethylenediamine, 1,10 phenanthroline (5<pcH<8) and humic acid (6.5<pcH<8.8). This behavior was attributed to the formation of ternary NpO₂ ⁺/silicate/ligand complexes. The effects of Ca(II) (1.00·10⁻³M) and Eu(III) (1.00·10⁻⁴ and 1.00·10⁻³M) ions on NpO₂ ⁺ sorption to suspended silicate were also investigated. On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, India.     

Continuation of functionals on ultradifferentiable function spaces

, c _k b _k . . . .

---

---

This work is supported by N.B.H.M. grant No. 48/1/94-R&D-II.     

Towards a biosynthetic infochemical communication system

By exploiting recent advances in the understanding of both pheromone biosynthesis pathways and the detection of molecules in the insect nervous system, we are developing a new class of technology for biosynthetic infochemical communication. Here we present a prototype instrument that comprises an integrated chemotransmitter, an odour pathway and a chemoreceiver controlled by a laptop computer. Our initial studies show that the system can transmit, receive and decode a set of volatiles commonly found in fruits. The system is capable of ratiometrically encoding information by releasing complex blends of compounds in specific ratios, detecting the transmitted blends with a sensor array and decoding the infochemical information using neuromorphic algorithms representing ratio processing in the macroglomerular complex (MGC) of the antennal lobe of the moth (e.g. Manduca sexta).     

Compatible mappings of type (B) and common fixed point theorems in Saks spaces

In this paper we first introduce the concept of compatible mappings of type (B) and compare these mappings with compatible mappings and compatible mappings of type (A) in Saks spaces. In the sequel, we derive some relations between these mappings. Secondly, we prove a coincidence point theorem and common fixed point theorem for compatible mappings of type (B) in Saks spaces.     

Effect of Cd1−xZnxS/ZnS core/shell quantum dot on the optical response and relaxation behaviour of ferroelectric liquid crystal

Dielectrics, polarizing optical microscopic and electro-optical measurements have been carried out on a core/shell quantum dot Cd_1?xZn_xS/ZnS dispersed ferroelectric liquid crystal (FLC). In the present study, quantum dots were dispersed into two different concentrations of 0.1 and 0.25 wt./wt.% in pure FLC. The electro-optical parameters of pure and QDs dispersed FLC were carried out as a function of applied voltage. A significant improvement in optical response time of QDs dispersed FLC system is one of the major finding of the present study which may be useful for fabrication of faster liquid crystal system.     

Magnetocaloric effects in Ni-Mn-X based Heusler alloys with X=Ga, Sb, In

The Mn-based Heusler alloys encompass a rich collection of useful materials from highly spin-polarized systems to shape memory alloys to magnetocaloric materials. In this work we have summarized our studies of magnetostructural transitions from paramagnetic austenite to ferromagnetic martesite phases at TMC in Ni₂MnGa-based alloys (Ni₂Mn_0.75Cu_0.25-xCo_xGa, Ni₂Mn_0.70Cu_0.30Ga_0.95Ge_0.05, Ni₂Mn_1-xCu_xGa, Ni_2+xMn_1-xGa, and Ni₂Mn_0.75-xCu_xGa), and martensitic transitions from the ferromagnetic austenite to the martesite state in off-stoichiometric Ni-Mn-(In/Sb) Heusler alloys. The phase transition temperatures and respective magnetic entropy changes (ΔS) depend on composition in these systems and have been determined from magnetization measurements in the temperature interval 5-400 K, and in magnetic fields up to 5 T. It is shown that, depending on the composition and doping scheme the “giant” ΔS=40-60 J/(kgK) (for a field change of 5 T) can be observed in the temperature range (300-360 K) for the Ga-based alloys. The interplay between or coupling of the various transitions in Ni₂Mn(Mn,X) systems with X=Sb and In leads to exchange bias effects, giant magnetoresistance, and both inverse and “normal” magnetocaloric effects.     

The structural and magnetic properties of Ni2Mn1−xBxGa Heusler alloys

The influence of the substitution of manganese by boron on the crystal structure and magnetic properties of Ni₂Mn_1−xB_xGa Heusler alloys with 0?x?0.5 has been investigated using X-ray diffraction, thermal expansion, resistivity, and magnetization measurements. The samples with concentrations x<0.25 were found to be of single phase and belonged to the cubic L2₁ crystal structure at room temperature. Crystal cell parameters of the alloys decreased from 5.830 to 5.825 Å with increasing boron concentration (x) from 0 to 0.25. The alloys were ferromagnetically ordered at 5 K and the saturation magnetization decreased with increasing boron concentration. The ferromagnetic ordering and structural transition temperatures for 0?x?0.3 have been observed and the phase (x−T) diagram of the Ni₂Mn_1−xB_xGa system was constructed. The phase (x−T) diagram indicates that the ground state of Ni₂Mn_1−xB_xGa alloys belongs to ferromagnetic martensitic, premartensitic, and austenitic phases in x?0.12, 0.12<x?0.18, and 0.18<x?0.3, respectively. The relative influence of cell parameters and electron concentrations on the phase diagram is discussed.     

Effect of Temperature and Solvent on the Structure of Amide Cavitands

Conformational changes of amide cavitands A – C were investigated at varied temperatures and in several solvents. While cavitands A and B , with comparatively smaller substituents such as Et and ⁱPr, were always in vase conformation in non‐polar solvents such as CDCl₃, CD₂Cl₂, (D₈)THF, and C₆D₆, their thermoswitching (vase to kite) was observed in polar solvents such as (D₇)DMF and (D₆)DMSO or in the presence of acid (TFA) and H‐bonding inhibitor (TFE). Intra‐ and interannular H‐bonds of A and B were clearly observed by low‐temperature ¹H‐NMR spectra in CDCl₃. No conformational change of cavitand C with bigger substituent (^tBu) was observed under any tested temperature range and in polar or non‐polar solvents; C was always in the kite conformation.     

Processes developed for the separation of europium (Eu) from various resources

Europium (Eu), one of the most significant rare earth (RE) elements, has wide applications as functional material in phosphor production, majorly used in fluorescent lamps, computer monitors, televisions etc. Eu is one of the three divalent lanthanides (along with Yb and Sm) having a reduction potential higher than ?2 V. This possibility of Eu reduction is attributed to a relatively stable half-filled 4f⁷ electronic configuration, thus providing a high stabilization energy and selective recovery. But the Eu recuperation from natural minerals is either accompanied with other REs or Eu is recovered as a group of light REs. Selective recovery of Eu has sparked the progress for its reutilization through recycling of secondary resources. The perspectives of reclaiming Eu as a value added product from various sources using different pyro-hydro or hybrid techniques are discussed. The systematic research and salient findings on methods, viz., reduction, leaching, solvent extraction, as well as combined methods scaled-up to commercial scale to recover Eu, are also reported with recommendations. Thus, this comparative as well as summarized review hopes to help researchers to develop feasible processes for Eu recovery.