Luminescence studies and effect of etching on cerium-doped CaS nanoparticles

Cerium-doped calcium sulphide nanoparticles were synthesized using the solid state diffusion method. The formed nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible absorption spectroscopy and photoluminescence (PL) spectroscopy. The XRD pattern confirmed a cubic CaS phase with an average grain size of 53 nm of the formed samples. The TEM image showed non-agglomerated particles with an average size of 60 nm, which is in close agreement with the XRD result. The PL-emission spectrum showed peaks at 506 and 565 nm due to the transition from the excited state to the ground state of Ce³⁺. The effect of etching has been studied on the luminescent properties of CaS:Ce phosphors. With an increase in the etching time there is decrease in the size of the particles, as a result of which the PL spectrum showed a slight blue shift. The UV-visible absorption spectrum also showed a blue shift with an increase in etching time, which is in agreement with the nanosize effect.     

Phase-space analysis of fragments formed in heavy-ion collisions

We study the effect of momentum-dependent interactions and a broader Gaussian on multifragmentation. We also look into the details of the fragment structure for a broader Gaussian and momentum-dependent interactions. We find that nucleons forming the fragments belong to the same region of the phase space.     

Characterization of Citrus nobilis Peel Methanolic Extract for Antioxidant,Antimicrobial, and Anti-Inflammatory Activity

Currently, the potential utilization of fruits and vegetable waste as a source of micronutrients and antioxidants has increased. The present study, therefore, aimed to determine the antimicrobial and anti-inflammatory activities of Citrus nobilis peel extract. A modified solvent evaporation technique was employed for peel extract preparation. For effective utilization of the natural product, quantitative analysis of phenolic compounds was carried out using liquid chromatography and mass spectroscopy technique. Phenolic and flavonoids were present in high amounts, while β-carotene and lycopene were present in vestigial amounts. The antimicrobial efficiency of peel extract was evaluated against four bacterial strains including Staphylococcus aureus (MTCC 3160), Klebsiella pneumoniae (MTCC 3384), Pseudomonas aeruginosa (MTCC 2295), and Salmonella typhimurium (MTCC 1254), and one fungal strain Candida albicans (MTCC 183), and zone of inhibition was comparable to the positive control streptomycin and amphotericin B, respectively. The extract of Citrus nobilis peels showed effective anti-inflammatory activity during human red blood cell membrane stabilization (HRBC) and albumin denaturation assay. The extracts also exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity ranging from 53.46 to 81.13%. Therefore, the obtained results suggest that Citrus nobilis peel could be used as an excellent source of polyphenols and transformed into value-added products.     

Photoluminescence measurements in the phase transition region of Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>S films

Thin films of Zn_1−x Cd _x S (0.1 ≤ x ≤ 0.5) were prepared by using pulsed laser ablation technique on corning glass substrates. Phase transition from cubic to hexagonal in Zn_1−x Cd _x S films is determined by X-ray diffraction analysis. We observed a lowering in the phase transition temperature with increase in the cadmium concentration. Transmission electron microscopy suggests the crystalline nature of thin films with average particle size of 15 nm. The grown Zn_1−x Cd _x S samples show the high peak intensity ratio of the near band edge emission to the defect center luminescence even at room temperature, which indicates the small concentration of complex defects in the samples. Photoluminescence measurement show stoichiometric dependence of the energy band gap and is found to have quadratic dependence on x.     

On the Bödewadt–Rosenblat flow

Fluid motion induced by the torsional oscillations (of angular velocity bΩcosω T) of an infinite disk in contact with an incompressible viscous rotating (with angular velocity aΩ) fluid of semi-infinite extent is analysed when the amplitude parameter α( = b/a) varies from zero to infinity. Composite solutions valid over the whole of the flow regime and specific expressions for the shearing stress components at the disk and for the axial flow in the far region are obtained for low and high frequencies of torsional oscillations. Using the method of matched asymptotic expansions, we find that the region of the mean flow increases with α and reaches a maximum before settling down to the Rosenblat profile. Series expressions (for α < 1) are deduced for physical quantities of interest when the fluid in the far field and the disk are rotating with different angular velocities (in the same or in the opposite sense), which agree well with the known numerical results. (Received: April 7, 2003; revised: September 29, 2005)     

Identification of Heat-Related ESTs in Moth Bean Through Suppression Subtraction Hybridization

Moth bean (Vigna aconitifolia (Jacq.) Marechal), an important grain-legume crop grown in hot desert regions of Thar, under scorching sun rays, was investigated for heat tolerance at molecular level. In the present study, we constructed a forward suppression subtractive hybridization (SSH) cDNA library of heat tolerant genotype RMO-40 to identify genes expressing under delayed response to elevated temperature. Heat induction was carried out by exposing 14-day-old seedlings to elevated temperature of 42 °C for 30 min. A total of 125 unigenes (33 contigs and 92 singletons) were derived by cluster assembly and sequence alignment of 200 ESTs; out of 125 unigenes, 21 (16 %) were found to be novel to moth bean. Gene ontology functional classification terms were retrieved for 98 (78.4 %) unigenes of which 73 (58.4 %) ESTs were functionally annotated (GO consensus) where 19 unigenes were annotated with 11 enzyme commission (EC) codes and were mapped to 25 different KEGG pathways. We have identified a majority of heat-shock proteins (constituting 35 % of the present library) aiding heat stress tolerance to moth bean. An expression level of 22 ESTs generated from the above SSH cDNA library was studied through semiquantitative RT-PCR assay simultaneously under 5 and 30 min of heat stress at 42 °C.     

New lower rim looped calix[4]arene for ratiometric and chromogenic recognition of Cu2+

A new calix[4]arene derivative in its cone conformation and bearing Schiff base loop at the lower rim has been synthesized and evaluated as a specific molecular probe for copper ions. The new molecular receptor 4 shows a selective visible change in color from colorless to yellow only in the presence of Cu²⁺ ions which was confirmed by a significant bathochromic shift (?λ_max = 76 nm) in its absorption spectrum. The stoichiometry of the copper complex was calculated to be 1:1. These results may help to design more efficient chemical sensors for determining copper in biological systems.     

Synthesis and evaluation of neutral anion receptors based on acylhydrazide-appended calix[4]arenes

A new class of neutral receptors based upon acylhydrazide-appended calix[4]arenes was synthesised and evaluated for recognition of anions. Detailed NMR and single-crystal X-ray analyses of one of the synthesised compounds reveal that anion recognition in such derivatives is achieved through cooperative hydrogen bond interactions. The presence of three centred NH–O and two OH–O hydrogen bonds at the lower rim of the synthesised calixarene architecture apparently helps the molecular scaffold to retain cone conformation to enable deployment of intermolecular hydrogen bonds for selective recognition of HSO₄ ^? ion in preference to F^?, Cl^?, Br^?, I^?, ClO₄ ^?, AcO^? and PF₆ ^? ions.     

Hydrazone comprising compounds as promising anti-infective agents: chemistry and structure-property relationship

Despite the adverse effects of microbial hazards on public health, major pharmaceutical firms have left the field of anti-infective development and a dramatic reduction in the number of researcher's intricated in the quest for new specific anti-infective leads. In the non-existence of an efficient forum for antibiotics development and over usage in human beings and animals, bacteria have demoralized this potential by gradually establishing the resistance toward most of the antibiotics used. Thus, the production of novel and successful anti-infective drugs is urgently required to combat this resistance. Hydrazones and hydrazides have mounted as a key-skeleton for the development of active drugs, due to their important biological and pharmacological profiles. Hydrazones are being manufactured as medicines by various investigators to fight against the ailments with maximal effects and minimal toxicity. This paper focuses on the outline of the literature results of recent years, incorporating the work on the anti-infective profile of hydrazone analogues. This review may also act as an excellent basis for the development of new derivatives of hydrazone as potential anti-infective mediators.