Enhanced luminescence of tris(carboxylato)uranyl(VI) complexes and energy transfer to Eu(III): a combined spectroscopic and theoretical investigation.

Complex formation between uranyl and carboxylate ligands (benzoate, nicotinate and isonicotinate) has been studied extensively by absorption and luminescence spectroscopy in acetonitrile medium. Experimental data had indicated the existence of stable and enhanced luminescent tris(carboxylato) uranyl(VI) complexes i.e. [UO2(L)3]- with D3h symmetry. The high luminescence of these complexes was due to the sensitization of the Oyl → U ligand to metal charge transfer (LMCT) emission by extremely intense equatorial (carboxylate ligands) LMCT bands. The variation in the experimentally observed parameters such as intensity of equatorial LMCT bands, luminescence lifetimes, quantum yields and structural parameters among tris(carboxylato) uranyl(VI) complexes are affirmed by quantum chemical calculations using density functional theory and the computational results are found to be in good agreement with experimental findings. Interestingly, in a very dilute mixture of [UO2(L)3]- and Eu(III), energy transfer from uranyl to Eu(III) is observed and it leads to the detection of europium at trace levels. This is an intriguing observation as none of the previous studies have reported such a low level of detection limit of Eu(III) by means of energy transfer from any metal.

On the varied emission fingerprints of particulate matter over typical locations of NCR (Delhi) - A perspective for mitigation plans.

Source apportionment study of PM2.5 using positive matrix factorization was performed to identify the emission characteristic from different sectors (sub-urban residential, industrial and rapidly urbanizing) of Delhi during winter. Chemical characterization of PM2.5 included metals (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn), water soluble ionic compounds (WSICs) (Cl-, NO3-, SO42- and NH4+) and Carbon partitions (OC, EC). Particulates (PM2.5) were collected on filter twice daily for stable and unstable atmospheric conditions, at the locations with specific characteristics, viz. Ayanagar, Noida and Okhla. Ions solely occupied 50% of the total PM2.5 concentration. Irrespective of location, high correlation between OC and EC (0.871-0.891) at p ≤ 0.1 is observed. Relatively lower ratio of NO3/SO4 at Ayanagar (0.696) and Okhla (0.84) denotes predominance of emission from stationary sources rather than mobile sources like that observed at Noida (1.038). Using EPA PMF5.0, optimum factors for each location are fixed based on error estimation (EE). Crustal dust, vehicular emission, biomass burning and secondary aerosol are the major contributing sources in all the three locations. Incineration contributes about 19% at Ayanagar and 18% at Okhla. Metal industries in Okhla contribute about 19% to PM2.5. These specific local emissions with considerable potency are to be targeted for long-term policymaking. Considerable secondary aerosol contribution (15%-24%) indicates that gaseous emissions also need to be reduced to improve air quality.

Nd(III) hypersensitive peak as an optical absorption probe for determining nitric acid in aqueous solution: An application to aqueous raffinate solutions in nuclear reprocessing.

A new method using Nd(III) absorption peak as a probe is described for the measurement of nitric acid concentration in aqueous solution. The hypersensitive peak of Nd(III) at 575.1 nm shows a substantial enhancement in the absorbance in comparison to other absorption peaks with increasing nitric acid concentration. The integrated area and absorbance of this hypersensitive peak show a linear dependency over a large dynamic range of 0.5-15.5 M of nitric acid. A methodology for the correction of spectral interference to the probing absorption peak of Nd(III) is also reported. The method is applied for the measurement of nitric acid in synthetic high level liquid waste solution and shown to be comparable to that obtained by titrimetric method. The present method can be easily adopted for the measurement of nitric acid concentration in aqueous raffinate solutions of nuclear reprocessing streams.

Post synthetically modified IRMOF-3 for efficient recovery and selective sensing of U(vi) from aqueous medium.

A simple and efficient route to develop various novel functionalized MOF materials for rapid and excellent recovery of U(vi) from aqueous medium, along with selective sensing has been demonstrated in the present study. In this connection, a set of four distinct post synthetically modified (PSM) iso-reticular metal organic frameworks were synthesized from IRMOF-3 namely, IRMOF-PC (2-pyridine carboxaldehyde), IRMOF-GA (glutaric anhydride), IRMOF-SMA (sulfamic acid), and IRMOF-DPC (diphenylphosphonic chloride) for the recovery and sensing of U(vi) from aqueous medium. The MOFs were characterized by Fourier transform infrared spectroscopy (FTIR), powder XRD, BET surface area analysis, thermogravimetric analysis (TGA), NMR (13C, 1H and 31P), Scanning Electron Microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Among all MOFs, post synthetically modified IRMOF-SMA showed enhanced thermal stability of about 420 °C. The MOFs were investigated for U(vi) sorption studies using a batch technique. All the MOFs exhibit excellent sorption capacity towards U(vi) (>90%) and maximum uptake was observed at pH 6. Sorption capacity of MOFs have the following order; IRMOF-3-DPC (300 mg U g-1) > IRMOF-SMA (292 mg U g-1) > IRMOF-PC (289 mg U g-1) > IRMOF-GA (280 mg U g-1) > IRMOF-3 (273 mg U g-1). IRMOF-DPC shows rapid sorption of uranium within 5 min with excellent uptake of U(vi) (>99%). The desorption of U(vi) was examined with different eluents and 0.01 M HNO3 was found to be most effective. The fluorescence sensing studies of U(vi) via IRMOF-3 and its PSM MOFs revealed high sensitivity and selectivity towards U(vi) over other competing rare earth metal ions (La3+, Ce4+, Sm3+, Nd3+, Gd3+, and Eu3+), wherein IRMOF-GA displayed an impressive detection limit of 0.36 mg L-1 for U(vi).

In vitro expression of vital virulent genes of clinical and environmental isolates of Cryptococcus neoformans/gattii in endothelial cells of human blood-brain barrier.

BACKGROUND: Evaluation of the pathogenesis of clinical and environmental cryptococcal isolates to the central nervous system is necessary for understanding the risk. This study was designed to determine the in vitro expression of six important virulent genes of Cryptococcus neoformans/gattii in Human Brain Microvascular Endothelial cells (hBMEC). METHODS: The hBMEC were infected with Cryptococcus to determine invasion and survival rate at 3, 12 and 24hours by subsequent colony count of internalized yeasts. The whole RNA of the intracellular Cryptococcus was extracted to quantify the expression of CAP10, PLB1, ENA1, URE1, LAC1, and MATα genes by real-time quantitative PCR for 3 and 12hours of infection. RESULTS: Invasion and survival rates were higher in clinical and standard strains of C. neoformans. A significant difference was observed among the clinical and environmental isolates for the expression of CAP10, ENA1, LAC1, MATα and URE1 at 3hours, and ENA1, LAC1, MATα, PLB1 and URE1 at 12hours. Clinical isolates showed significant upregulation of all the genes except PLB1, which was higher in environmental isolates. Relative expressions at the two time-points showed statistically significant (P=0.043) changes for the clinical isolates and no significance (P=0.063) for environmental isolates. CONCLUSION: The C. gattii (VGI) isolates showed significantly lower invasion and survival than C. neoformans (VNI, and VNII) irrespective of their sources. Clinical isolates exhibited higher expression for the majority of the virulent genes until 12hours of infection, probably due to their better adaptation in the host system and enhanced pathogenicity than the environmental counterparts.

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile.

Uranyl tris nitrato i.e. [UO2 (NO3 )3 ]- was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467 nm peak of uranyl tris nitrato showed a linear response in the range 0-5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.

A rare case of multiple brain abscess and probably disseminated phaeohyphomycosis due to Cladophialophora bantiana in an immunosuppressed individual from India.

Cladophialophora bantiana, a dematiaceous neurotropic mold causes rare and lethal brain abscess, commonly in immunocompetent hosts. We report a rare and probably a case of disseminated infection with this black mold in an immunosuppressed individual from India. A 55-year-old diabetic male presented with severe headache, blurred-vision, behavioural abnormalities, eye-pain and ear-discharge. He was undergoing treatment for hypertension, prostatomegaly and obstructive pulmonary disease. He was on steroids for the past six years for uveitis. Haematology reports indicated elevated WBC and platelet count. He was negative for HIV, hepatitis, autoimmune antibodies and tumour markers. CD4 count was within normal limits. Brain magnetic resonance imaging revealed multiple ring-enhancing lesions and oedema in the left tempero-parietal region. Chest X-ray showed irregular consolidations in right paracardiac region and confluence in both lungs. Positron Emission Tomography of whole body revealed multiple lesions in brain, lungs, lymph nodes and C3-vertebrae. Histopathology of the lung lesion showed non-tuberculous infectious pathology and brain lesions showed necrosis with occurrence of pigmented hyphal fungi. The pus aspirated during surgical excision of brain lesions grew black mold, identified as C. bantiana. Although patient was started on intravenous Voriconazole, he succumbed to the infection after 7 days. The lesion was initially suspected to be of tuberculous etiology, and the lesions in lungs were also suggestive of malignancy, which was however ruled out by histopathological examination. Such diagnostic dilemmas are common in the infection caused by Cladophialophora, which can cause treatment delay and death. Early diagnosis is therefore mandatory for the rapid treatment and survival of patients.

Photocatalytic and antibacterial activity of cadmium sulphide/zinc oxide nanocomposite with varied morphology.

Nanocomposites with multifunctional application prospects have already dragged accelerating interests of materials scientists. Here we present CdS/ZnO nanocomposites with different morphology engineering the precursor molar ratio in a facile wet chemical synthesis route. The materials were structurally and morphologically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and high-resolution transmission electron microscopy (HRTEM). The growth mechanism of the composite structure with varying molar ratio is delineated with oriented attachment self assemble techniques. Photocatalytic activity of CdS/ZnO nanocomposites with varying morphology were explored for the degradation of rhodamine B (RhB) dye in presence of visible light irradiation and the results reveal that the best catalytic performance arises in CdS/ZnO composite with 1: 1 ratio. The antibacterial efficiency of all nanocomposites were investigated on Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia without light irradiation. Antibacterial activity of CdS/ZnO nanocomposites were studied using the bacteriological test-well diffusion agar method and results showed significant antibacterial activity in CdS/ZnO composite with 1:3 ratio. Overall, CdS/ZnO nanocomposites excel in different potential applications, such as visible light photocatalysis and antimicrobial activity with their tuneable structure.

Association of p53 codon72 Arg>Pro polymorphism with susceptibility to nasopharyngeal carcinoma: evidence from a case-control study and meta-analysis.

Tumor suppressor p53 is a critical player in the fight against cancer as it controls the cell cycle check point, apoptotic pathways and genomic stability. It is known to be the most frequently mutated gene in a wide variety of human cancers. Single-nucleotide polymorphism of p53 at codon72 leading to substitution of proline (Pro) in place of arginine (Arg) has been identified as a risk factor for development of many cancers, including nasopharyngeal carcinoma (NPC). However, the association of this polymorphism with NPC across the published literature has shown conflicting results. We aimed to conduct a case-control study for a possible relation of p53 codon72 Arg>Pro polymorphism with NPC risk in underdeveloped states of India, combine the result with previously available records from different databases and perform a meta-analysis to draw a more definitive conclusion. A total of 70 NPC patients and 70 healthy controls were enrolled from different hospitals of north-eastern India. The p53 codon72 Arg>Pro polymorphism was typed by polymerase chain reaction, which showed an association with NPC risk. In the meta-analysis consisting of 1842 cases and 2330 controls, it was found that individuals carrying the Pro allele and the ProPro genotype were at a significantly higher risk for NPC as compared with those with the Arg allele and the ArgArg genotype, respectively. Individuals with a ProPro genotype and a combined Pro genotype (ProPro+ArgPro) also showed a significantly higher risk for NPC over a wild homozygote ArgArg genotype. Additionally, the strength of each study was tested by power analysis and genotype distribution by Hardy-Weinberg equilibrium. The outcome of the study indicated that both allele frequency and genotype distribution of p53 codon72 Arg>Pro polymorphism were significantly associated with NPC risk. Stratified analyses based on ethnicity and source of samples supported the above result.

Transiently responsive protein-polymer conjugates via a 'grafting-from' RAFT approach for intracellular co-delivery of proteins and immune-modulators.

We report on transiently responsive protein-polymer conjugates that temporarily change their protein conformation from the soluble to the particle-like state. 'Grafting-from' RAFT polymerization of a dioxolane-containing acrylamide with a protein macroCTA is used to design polymer-protein conjugates that self-assemble into nanoparticles at physiological temperature and pH. Acid triggered hydrolysis of the dioxolane units into diol moeities rendered the conjugates fully water soluble irrespective of temperature.

Fluorescence and co-fluorescence of Tb(3+) and Eu(3+) in acetonitrile using 2,6-pyridine dicarboxylic acid as ligand.

Fluorescence from Tb(3+) and Eu(3+) complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent. The enhancement in fluorescence intensity because of non-aqueous environment provided by the MeCN is less significant, where as fluorescence enhancement of more than two orders of magnitude has been observed with the addition of La(3+); a process known as co-fluorescence in MeCN. The present study demonstrates for the first time co-fluorescence of Tb(3+) and Eu(3+) with excitation through the absorption of PDA. Intermolecular energy transfer is believed to be responsible for co-fluorescence enhancement and it becomes possible as the quenching due to water at the secondary coordination spheres of Tb(3+) and Eu(3+) is reduced when MeCN is used as solvent.

Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: a new luminescent uranyl benzoate specie.

Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3](-) which is highly luminescent. In particular, three sharp bands at 431, 443, 461nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68µs which is much more compared to the lifetime of uncomplexed uranyl (20µs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3](-) specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed.

Estimation of Eu(3+) in bulk uranium by ligand sensitized fluorescence in dimethyl sulphoxide.

Ligand sensitized fluorescence of europium ion using thenoyltrifluoroacetone (TTA) as a sensitizing ligand and dimethyl sulphoxide (DMSO) as a solvent is studied for the first time. TTA ligand enhances the fluorescence of Eu(3+) by a factor of 40000 in DMSO. Linearity is obtained for a concentration range of 0.076-7.6ng/mL of Eu(3+) with a detection limit of 7.6pg/mL. The quenching of Eu(3+)-TTA fluorescence by uranium matrix was studied in different solvents and found to be less in DMSO. Consequently, estimation of Eu(3+) in a large excess of uranium becomes a possibility without the need to separate uranium from the solution, which has been demonstrated in this paper. Satisfactory results are obtained when Eu(3+) is present at a concentration of 0.6µg/g in uranium.

Macroporous silicon based simple and efficient trapping platform for electrical detection of Salmonella typhimurium pathogens.

A thermally oxidized macroporous silicon substrate with simple electrode structure without interdigitated electrode configuration has been reported for the detection of Salmonella typhimurium pathogens by electrical impedance measurement using antibody-antigen binding method. Macroporous silicon which has been fabricated by anodizing silicon in HF and DMF solution is a regular network of pores of 1-2 microm diameters. This has been thermally oxidized to yield the surface hydrophilic for antibody immobilization as well as provide suitable electrical insulation of the metal contacts from the underlying conducting silicon substrate. The macroporous silicon surface has been immobilized by Salmonella specific antibody and has been tested with different concentration of S. typhimurium pathogens in phosphate buffer solution (PBS). It has been found that such macroporous silicon substrates is capable of detecting down to 10(3)CFU/ml in pure culture using a 3 mm x 1 mm electrode structure with a wide spacing of 1mm. The selectivity of the macroporous silicon substrates with reference to S. typhimurium has been tested to be satisfactory by carrying out controlled experiments with Escherichia coli O157:H7.

Ligand-sensitized fluorescence of Tb3+ in Tb3+-dibutylphosphate complexes: application for the estimation of DBP.

The fluorescence of Tb(3+) is sensitized by complexation with dibutylphosphate (DBP) and tri-n-butylphosphate (TBP). The excitation maximum for the Tb(3+)-DBP complex occurs at 218.5 nm, while that for the Tb(3+)-TBP complex is observed at 228.0 nm. Both complexes yield Tb(3+) fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1-10% of TBP, in TBP/dodecane solutions.

Immunoreactive antigens of the outer membrane protein of Aeromonas hydrophila, isolated from goldfish, Carassius auratus (Linn.).

Aeromonas hydrophila causes disease under stress conditions or in concert with infection by other pathogens in goldfish. Sero-diagnostic and/or immunoprophylactic tools against Aeromonas infection in goldfish are not available so far. The present study was undertaken to fractionate and characterise the outer membrane proteins (OMP) of A. hydrophila and to identify suitable immunoreactive components. A total of 10 fractions were generated from crude OMP antigens upon gel permeation and subsequent ion-exchange chromatography. One of the fractionated antigens (GPID2), primarily a 57-kDa polypeptide, showed maximum sero-reactivity, even higher than the crude OMP. Suitability of GPID2 antigen for use in diagnostic preparations was assessed by dip-stick ELISA. In vitro goldfish lymphoproliferative ability of fractionated antigen, GPIID2 (primarily a 23-kDa polypeptide) was observed to be higher than all the fractionated antigens as well as crude OMP. It can be concluded that the 57 kDa and 23 kDa polypeptides of the OMP of A. hydrophila, possessing high immunoreactivity, should be given due attention while preparing immunodiagnostic and immunoprophylatic tools against Aeromonas infections in goldfish.

A pilot survey on hand washing among some communities of West Bengal.

A cross-sectional observational study was carried out between April to May 2006 by interview method and observation technique with the objective to know the knowledge regarding hand washing in the community and it was done in the slum and nonslum urban areas and also one rural area. The result shows that in urban slum area 98% washed their hands with soap after defecation; Only 36%, 16% and 2% washed their hands with soap before meal, before serving food and before cooking respectively. However, it was observed that 69% used soap and water for hand washing after cleaning the child's faeces. In rural area 71% used soap and water after defecation while 26% used mud or ash. Only 13%, 1%, 1% and 5% used soap and water before meal, before serving food, before cooking and after cleaning the child's faeces. 82.35% of respondents in non slum area and 89% of respondents in rural area considered that diarrhoea and dysentery could be prevented by hand washing while they did not give importance to hand washing in prevention of diarrhoea over other methods like cleanliness, boiling and purification of water. ARI was much higher (25.72%) in rural area followed by slum area (13.77%) and non-slum area (3.87%). Out of 30 observations among 302 interview made on hand-washing only first step i.e. palm washing (transient rubbing the palm with soap) was followed by all the participants observed. Time taken for such hand-washing was only around five seconds (ideal 15-30 seconds) in urban slum and rural areas while in non slum area it varied between 7-10 seconds on an average. No one followed any other steps of hand-washing, recommended by IFH.

Effect of ligand structure on synergism in Tb3+-aromatic acid complexes: fluorescence lifetime studies.

The fluorescence of Tb3+ sensitized by aromatic carboxylic acid ligands (benzoic, monomethylphthalic, monomethylterephthalic, trimesic, terephthalic, isophthalic, phthalic and mellitic acids) and the synergism displayed by these complexes when treated with TOPO/Triton X-100 have been studied by measuring lifetimes of Tb3+ emission. The lifetime of Tb3+ fluorescence was not significantly altered following complex formation with aromatic carboxylic acids, even though a significant enhancement in the Tb3+ fluorescence intensity was observed in every single case. However, when these Tb3+-aromatic acid complexes were treated with TOPO/Triton X-100, the lifetimes of the Tb3+ fluorescence increased markedly, but only with certain acids. Interestingly, even amongst the acids that showed an increase in lifetime with TOPO/Triton X-100, the lifetimes as a function of the pH of the solution was strongly dependent on the structure of the ligand. These differences and the reasons for such behavior are discussed, which shed light on the role of the structure of the ligand on the synergism process.

First crystallographic signature of amyloid-like fibril forming beta-sheet assemblage from a tripeptide with non-coded amino acids.

The model tripeptide Boc-beta-Ala(1)-Aib(2)-beta-Ala(3)-OMe 1 [beta-Ala: beta-alanine, Aib: alpha-aminoisobutyric acid] forms an infinite parallel beta-sheet structure through intermolecular interactions in single crystals and from the SEM diagram of this peptide, it is evident that the compound has fibrillar morphology, a characteristic of neurodegenerative disease causing amyloid aggregate.

tert-butyl N-[2-[N-(N, N'-dicyclohexylureidocarbonylethyl)carbamoyl]prop-2-yl]carbamate.

The title compound, C(25)H(44)N(4)O(5), exhibits a turn with the main chain reversing direction, held together by an intramolecular N-H.O hydrogen bond. In the urea fragment, a notable amide C-N bond between the carboxyl C and the tertiary N atom shows marked single-bond character [1.437 (2) A]. The dihedral angle of the beta-alanyl residue, centrally located in the turn, is gauche [69.2 (2) degrees ]. The packing is mediated by two intermolecular hydrogen bonds and van der Waals contacts involving the methyl moieties and the cyclohexyl rings.