Plasmonic resonance instigated enhanced photoluminescence in quantum dot dispersed nematic liquid crystal

In the present investigation, the optical property of the nematic sample p-methoxybenzylidene p-decylaniline, dispersed with SiO₂ quantum dot (QD), has been reported. Enhanced luminescence has been observed from nematic-QD composites. Surface plasmonic effect along with QD exciton has been highlighted to discuss the observed intensification in photoluminescence. The intensified photoemission from the nematic composites can also be inferred from improved orientational behaviour of the liquid crystal molecules due to dispersion of QDs. Variation in the intensity of photoabsorption can be harnessed for development of luminescent display devices and optical parameter-driven scientific applications.     

Development of 99Mo-alfa-benzoin oxime complex as industrial radiotracer for identification of leaky heat exchanger and its validation with 99mTc

Journal of Radioanalytical and Nuclear Chemistry - In the traditional medicine of Iran, some herbal medicines are used for treating of high blood sugar. In this study, the concentration of Ca, Cr,...     

Observation of compensation effect for isothermal crystallization in glassy Se80?xGe20Inx and Se78?xGe22Bix alloys

Many activated phenomena, including solid state diffusion in crystals and polymers, dielectric relaxation, conduction and thermally stimulated processes in polymers, and electronic conduction in amorphous semiconductors obey the compensation law or Meyer-Neldel rule. In the present paper, we discuss the results of investigation into the compensation effect observed under isothermal crystallization in glassy Se₇₀Te_30−xSb_x alloys. It is found that the relation between the pre-exponential factor K_o and activation energy of crystallization E_c follows the Meyer-Neldel rule for the alloys studied. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 45–51, March, 2008.     

Manifestation of strong magneto-electric dipolar coupling in ferromagnetic nanoparticles−FLC composite: evaluation of time-dependent memory effect

Rod-shaped 5 wt.% copper-doped ZnO (ZnO:Cu²⁺) ferromagnetic nanoparticles (NPs), prepared by hydrothermal method, were dispersed in ferroelectric liquid crystal (FLC) named Felix 17/100. The effect of ferromagnetic NPs on the physical properties of FLC material (Felix 17/100) has been investigated by dielectric, electro-optical and polarising optical microscopic methods. A noteworthy time-dependent memory has been observed in the NPs-dispersed FLC composite attributed to the coupling of magnetic field associated to NPs with the director orientation of FLC. Improvement in spontaneous polarisation and dielectric susceptibility of FLC material has been ensued with the addition of ferromagnetic NPs. Faster electro-optic response, at lower applied voltage, has also been observed in NPs-dispersed FLC composite. These changes are accredited to the magneto-electric dipolar coupling existing due to the interactions between magnetic-dipole and electric-dipole moments of magnetic NPs and FLC material, respectively. The formation of periodic domains capable to show memory effect has been observed in composite. The observed time-dependent memory was confirmed by dielectric and electro-optical methods. FLC material enriched with the properties of ferromagnetic NPs can be utilised in advanced multifunctional optical devices, time-dependent memory-based security devices and computational purposes.     

Isointricatinol, a new antioxidant homoisoflavonoid from the roots of Caesalpinia digyna Rottler

A new homoisoflavonoid, isointricatinol (1), together with eight known homoisoflavonoids, three flavonoids, bergenin and 11-O-galloylbergenin were isolated from the EtOAc fraction of MeOH extract of Caesalpinia digyna roots and evaluated for the antioxidant activity against DPPH and ABTS free radicals. The structure of 1 was elucidated by various spectroscopic techniques and found to be a Z-isomer of 7,8-dihydroxy-3-(4'-methoxybenzyl)chroman-4-one. Compound 1 was found to exhibit mild to moderate free radical scavenging effect against DPPH (IC(50), 85.50?μM) and ABTS (IC(50), 44.13?μM) radicals.     

Carbonylative Suzuki coupling reactions catalyzed by ONO pincer–type Pd(II) complexes using chloroform as a carbon monoxide surrogate

Benzoylhydrazone Schiff base–ligated three new ONO pincer–type palladium(II) complexes, [(PdL¹(PPh₃)] ( 1 ), [(PdL²(PPh₃)] ( 2 ), and [(PdL³(PPh₃)] ( 3 ), were synthesized by the reaction of the respective ligand, N-(2-hydroxybenzylidene)benzohydrazide (HL¹), N-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (HL²), or N-(5-bromo-2-hydroxybenzylidene) benzohydrazide (HL³), with Pd(OAc)₂ and PPh₃ in methanol and isolated as air-stable reddish-orange crystalline solids in high yields (78%–83%). All three complexes were fully characterized by elemental analysis, Fourier-transform infrared spectroscopy, UV–Visible, ¹H nuclear magnetic resonance (NMR), ¹³C{¹H} NMR, and ³¹P{¹H} NMR spectroscopic studies. The molecular structure of all three complexes was established unambiguously by single-crystal X-ray diffraction studies which revealed a distorted square planar geometry of all three complexes. The ONO pincer–type ligands occupied three coordination sites at the palladium, while the fourth site is occupied by the monodentate triphenylphosphine ligand. The catalytic potential of all three complexes was explored in the carbonylative Suzuki coupling of aryl bromides and iodides with arylboronic acids to yield biaryl ketones, using CHCl₃ as the source of carbonyl. The reported protocol is convenient and safe as it obviates the use of carbon monoxide (CO) balloons or pressured CO reactors which are otherwise needed for the carbonylation reactions. The methodology has been successfully applied to the synthesis of two antineoplastic drugs, namely, phenstatin and naphthylphenstatin, in good yields (81% and 85%, respectively). Under the optimized reaction conditions, complex 2 exhibited the best catalytic activity in the carbonylative Suzuki couplings. The reported catalysts have wide reaction scope with good functional group tolerance. All catalysts could be retrieved from the reaction after completion and recycled up to three times with insignificant loss in the catalytic activity.     

Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO2 nanoparticles

In the present work TiO₂ nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO₂ NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.     

Ion selective electrode for uranium based on composite multiwalled carbon nanotube-benzo-15-crown-5 in PVC matrix coated on graphite rod

Development of a composite multiwalled carbon nanotube (MWNT) polyvinyl chloride (PVC) with benzo-15-crown-5 (B15C5) as ionophore sensor responsive to uranyl ion is described. The composite MWNT-PVC membrane containing the active ingredients was casted on the surface of a graphite rod. The sensor incorporates B15C5 as electroactive material, ortho-nitrophenyl octyl ether (o-NPOE) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an ion discriminator. The sensor displays a rapid and linear response over the concentration range of 1 × 10^?1 to 1 × 10^?7 M with a slope of 29.9 ± 0.4 mV per decade. The detection limit of this electrode was found to be 5.4 × 10^?8 M and the working pH range is from 2.5 to 4.5. Interference from many inorganic cations viz. Na⁺, K⁺, Sr²⁺, Zn²⁺ and Fe³⁺ is negligible for the sensor. Application to the determination of uranium in ores and effluent samples gives results with good correlation which are comparable with data obtained by inductively coupled plasma atomic emission spectrometry. The electrode has been characterized using surface techniques.     

Amorphous-to-crystalline transition in Ge22Se78−x Bi x system

Summary Crystallization kinetics is studied in glassy Ge₂₂Se_78−x Bi _x (0≤x≤10) using isothermal annealing at various temperatures between the glass transition and melting. D.c. conductivity is taken as a parameter to estimate the extent of crystallization (α). The activation energy of crystallization (ΔE) and the order parameter (n) are calculated by fitting the values of α in Avrami’s equations of isothermal transformation. The results indicate that ΔE is highly composition dependent and decreases as the Bi concentration increases.