Morphological Effects of G-Quadruplex Stabilization Using a Small Molecule in Zebrafish

Zebrafish (Danio rerio) embryos are transparent and advantageous for studying early developmental changes due to ex utero development, making them an appropriate model for studying gene expression changes as a result of molecular targeting. Zebrafish embryos were injected with a previously reported G-quadruplex selective ligand, and the phenotypic changes were recorded. We report marked discrepancies in the development of intersegmental vessels. In silico analysis determined that the putative G-quadruplex motif occur in the upstream promoter region of the Cdh5 (N-cadherin) gene. A real-time polymerase chain reaction-based investigation indicated that in zebrafish, CDH-2 (ZN-cad) was significantly downregulated in the ligand-treated embryos. Biophysical characterization of the interaction of the ligand with the G-quadruplex motif found in this promoter yielded strong binding and stabilization of the G-quadruplex with this ligand. Hence, we report for the first time the phenotypic impact of G-quadruplex targeting with a ligand in a vertebrate organism. This study has unveiled not only G-quadruplex targeting in non-human animal species but also the potential that G-quadruplexes can provide a ready tool for understanding the phenotypic effects of targeting certain important genes involved in differentiation and developmental processes in a living eukaryotic organism.

An oxygen evolution Co-Ac catalyst - the synergistic effect of phosphate ions

Formation of an amorphous cobalt based oxygen evolution catalyst called Co-Pi has been recently reported from a neutral phosphate buffer solution containing Co2+. But the concentration of Co2+ is as low as 0.5 mM due to poor solubility of a cobalt salt in phosphate medium. In the present study, a cobalt acetate based oxygen evolution catalyst (Co-Ac) is prepared from a neutral acetate buffer solution, where the solubility of Co2+ is very high (>100 times in comparison with phosphate buffer solution). The Co-Ac possesses better catalytic activity than the Co-Pi with an additional advantage of easy bulk scale preparation. The comparative studies on the oxygen evolution reaction (OER) activity of Co-Ac and Co-Pi in phosphate and acetate buffer electrolytes reveal that the Co-Ac exhibits enhanced synergistic catalytic activity in phosphate solution, probably due to partial substitution of acetate in the catalyst layer by phosphate, resulting in the formation of a Co-Ac-Pi catalyst.

Successful data recovery from oscillation photographs containing strong polycrystalline diffraction rings from an unknown small-molecule contaminant: preliminary structure solution of Salmonella typhimurium pyridoxal kinase (PdxK)

Pyridoxal kinase (PdxK; EC 2.7.1.35) belongs to the phosphotransferase family of enzymes and catalyzes the conversion of the three active forms of vitamin B-6, pyridoxine, pyridoxal and pyridoxamine, to their phosphorylated forms and thereby plays a key role in pyridoxal 5 `-phosphate salvage. In the present study, pyridoxal kinase from Salmonella typhimurium was cloned and overexpressed in Escherichia coli, purified using Ni-NTA affinity chromatography and crystallized. X-ray diffraction data were collected to 2.6 angstrom resolution at 100 K. The crystal belonged to the primitive orthorhombic space group P2(1)2(1)2(1), with unitcell parameters a = 65.11, b = 72.89, c = 107.52 angstrom. The data quality obtained by routine processing was poor owing to the presence of strong diffraction rings caused by a polycrystalline material of an unknown small molecule in all oscillation images. Excluding the reflections close to powder/polycrystalline rings provided data of sufficient quality for structure determination. A preliminary structure solution has been obtained by molecular replacement with the Phaser program in the CCP4 suite using E. coli pyridoxal kinase (PDB entry 2ddm) as the phasing model. Further refinement and analysis of the structure are likely to provide valuable insights into catalysis by pyridoxal kinases.

Strategies for high efficiency and stability in biogas-fuelled small engines

This work assesses the performance of small biogas-fuelled engines and explores high-efficiency strategies for power generation in the very low power range of less than 1000 W. Experiments were performed on a small 95-cc, single-cylinder, four-stroke spark-ignition engine operating on biogas. The engine was operated in two modes, i.e., `premixed' and `fuel injection' modes, using both single and dual spark plug configurations. Measurements of in-cylinder pressure, crank angle, brake power, air and fuel flow rates, and exhaust emissions were conducted. Cycle-to-cycle variations in engine in-cylinder pressure and power were also studied and assessed quantitatively for various loading conditions. Results suggest that biogas combustion can be fairly sensitive to the ignition strategies thereby affecting the power output and efficiency. Further, results indicate that continuous fuel injection shows superior performance compared to the premixed case especially at low loads owing to possible charge stratification in the engine cylinder. Overall, this study has demonstrated for the first time that a combination of technologies such as lean burn, fuel injection, and dual spark plug ignition can provide highly efficient and stable operation in a biogas-fuelled small S.I. engine, especially in the low power range of 450-1000W. (C) 2014 Elsevier Inc. All rights reserved.

Ligational behaviour of (E)-2-amino-N ` -1-(2-hydroxyphenyl) ethylidene]benzohydrazide towards later 3d metal ions: X-ray crystal structure of nickel(IV) complex

Ligational behaviour of (E)-2-amino-N'-1-(2-hydroxyphenyl)ethylidene]benzohydrazide (Aheb) towards later 3d metal ionscopper(II), cobalt(II), manganese(II), zinc(II), cadmium(II) and nickel(IV)] has been studied. Their structures have been elucidated on the basis of spectral (IR, H-1 NMR, UV-Vis, EPR and FAB-mass), elemental analyses, conductance measurements, magnetic moments, and thermal studies. During complexation Ni(II) ion has got oxidized to Ni(IV). The changes in the bond parameters of the ligand on complexation has been discussed by comparing the crystal structure of the ligand with that of its Ni(IV) complex. The X-ray single crystal analysis of Ni(aheb)(2)]Cl-2 center dot 4H(2)O has confirmed an octahedral geometry around the metal ion. EPR spectra of the Cu(II) complex in polycrystalline state at room (300 K) and liquid nitrogen temperature (77 K) were recorded and their salient features are reported. (C) 2014 Elsevier B.V. All rights reserved.

Multichannel-Emissive V-Shaped Boryl-BODIPY Dyads: Synthesis, Structure, and Remarkably Diverse Response toward Fluoride

Three new V-shaped boryl-BODIPY dyads (1-3) were synthesized and structurally characterized. Compounds 1-3 are structurally close molecular siblings differing only in the number of methyl substituents on the BODIPY moiety that were found to play a major role in determining their photophysical behavior. The dyads show rare forms of multiple-channel emission characteristics arising from different extents of electronic energy transfer (EET) processes between the two covalently linked fluorescent chromophores (borane and BODIPY units). Insights into the origin and nature of their emission behavior were gained from comparison with closely related model molecular systems and related photophysical investigations. Because of the presence of the Lewis acidic triarylborane moiety, the dyads function as highly selective and sensitive fluoride sensors with vastly different response behaviors. When fluoride binds to the tricoordinate borane center, dyad 1 shows gradual quenching of its BODIPY-dominated emission due to the ceasing of the (borane to BODIPY) EET process. Dyad 2 shows a ratiometric fluorescence response for fluoride ions. Dyad 3 forms fluoride-induced nanoaggregates that result in fast and effective quenching of its fluorescence intensity just for similar to 0.3 ppm of analyte (i.e., 0.1 equiv 0.26 ppm of fluoride). The small structural alterations in these three structurally close dyads (1 - 3) result in exceptionally versatile and unique photophysical behaviors and remarkably diverse responses toward a single analyte, i.e., fluoride ion.

Robust dielectric properties of B-site size-disordered hexagonal Ln(2)CuTiO(6) (Ln = Y, Dy, Ho, Er, and Yb)

Hexagonal Ln(2)CuTiO(6) (Ln = Y, Dy, Ho, Er, and Yb) exhibits a rare combination of interesting dielectric properties, in the form of relatively large dielectric constants (epsilon' > 30), low losses, and extremely small temperature and frequency dependencies, over large ranges of temperature and frequency Choudhury et al., Appl. Phys. Lett. 96, 162903 (2010) and Choudhury et al., Phys. Rev. B 82, 134203 (2010)], making these compounds promising as high-k dielectric materials. The authors present a brief review of the existing literature on this interesting class of oxides, complimenting it with spectroscopic data in conjunction with first-principles calculation results, revealing a novel mechanism underlying these robust dielectric properties. These show that the large size differences in Cu2+ and Ti4+ at the B-site, aided by an inherent random distribution of CuO5 and TiO5 polyhedral units, frustrates the ferroelectric instability, inherent to the noncentrosymmetric P6(3) cm space group of this system, and gives rise to the observed relatively large dielectric constant values. Additionally, the phononic contributions to the dielectric constant are dominated primarily by mid-frequency (>100 cm(-1)) polar modes, involving mainly Ti4+ 3d(0) ions. In contrast, the soft polar phonon modes with frequencies typically less than 100 cm(-1), usually responsible for dielectric properties of materials, are found to be associated with non-d(0) Cu2+ ions and to contribute very little, giving rise to the remarkable temperature stability of dielectric properties of these compounds. (C) 2014 American Vacuum Society.

Syntheses and structural investigation of some alkali metal ion-mediated (LVO2-)-O-V (L2- = tridentate ONO ligands) species: DNA binding, photoinduced DNA cleavage and cytotoxic activities

Eight alkali metal ion-mediated dioxidovanadium(V), {(VO2L1-6)-O-V} A(H2O)n]proportional to, complexes for A = Li+, Na+, K+ and Cs+, containing tridentate aroylhydrazonate ligands coordinating via ONO donor atoms, are described. All the synthesised ligands and the metal complexes were successfully characterised by elemental analysis, IR, UV-Vis and NMR spectroscopy. X-ray crystallographic investigation of 3, 5-7 shows the presence of distorted NO4 coordination geometries for LVO2- in each case, and varying mu-oxido and/ or mu-aqua bridging with interesting variations correlated with the size of the alkali metal ions: with small Li+, no bridging-O is found but four ion aggregates are found with Na+, chains for K+ and finally, layers for Cs+. Two (5) or three-dimensional (3, 6 and 7) architectures are consolidated by hydrogen bonding. The dioxidovanadium(V) complexes were found to exhibit DNA binding activity due to their interaction with CT-DNA by the groove binding mode, with binding constants ranging from 10(3) to 10(4) M-1. Complexes 1-8 were also tested for DNA nuclease activity against pUC19 plasmid DNA which showed that 6 and 7 had the best DNA binding and photonuclease activity; these results support their good protein binding and cleavage activity with binding constants ranging from 104 to 105 M-1. Finally, the in vitro antiproliferative activity of all complexes was assayed against the HeLa cell line. Some of the complexes (2, 5, 6 and 7) show considerable activity compared to commonly used chemotherapeutic drugs. The variation in cytotoxicity of the complexes is influenced by the various functional groups attached to the aroylhydrazone derivative.

Small molecule inhibitors of HCV replication from Pomegranate

Hepatitis C virus (HCV) is the causative agent of end-stage liver disease. Recent advances in the last decade in anti HCV treatment strategies have dramatically increased the viral clearance rate. However, several limitations are still associated, which warrant a great need of novel, safe and selective drugs against HCV infection. Towards this objective, we explored highly potent and selective small molecule inhibitors, the ellagitannins, from the crude extract of Pomegranate (Punica granatum) fruit peel. The pure compounds, punicalagin, punicalin, and ellagic acid isolated from the extract specifically blocked the HCV NS3/4A protease activity in vitro. Structural analysis using computational approach also showed that ligand molecules interact with the catalytic and substrate binding residues of NS3/4A protease, leading to inhibition of the enzyme activity. Further, punicalagin and punicalin significantly reduced the HCV replication in cell culture system. More importantly, these compounds are well tolerated ex vivo and `no observed adverse effect level' (NOAEL) was established upto an acute dose of 5000 mg/kg in BALB/c mice. Additionally, pharmacokinetics study showed that the compounds are bioavailable. Taken together, our study provides a proof-of-concept approach for the potential use of antiviral and non-toxic principle ellagitannins from pomegranate in prevention and control of HCV induced complications.

Study of liquid fuel transport in a small carburetted engine in the context of cold-start HC emission control

In the present study, a detailed visualization of the transport of fuel film has been performed in a small carburetted engine with a transparent manifold at the exit of the carburettor. The presence of fuel film is observed significantly on the lower half of the manifold at idling, while at load conditions, the film is found to be distributed all throughout the manifold walls. Quantitative measurement of the fuel film in a specially-designed manifold of square cross section has also been performed using the planar laser-induced fluorescence (PLIF) technique. The measured fuel film thickness is observed to be of the order of 1 nun at idling, and in the range of 0.1 to 0.4 mm over the range of load and speed studied. These engine studies are complemented by experiments conducted in a carburettor rig to study the state of the fuel exiting the carburettor. Laser-based Particle/Droplet Image Analysis (PDIA) technique is used to identify fuel droplets and ligaments and estimate droplet diameters. At a throttle position corresponding to idling, the fuel exiting the carburettor is found to consist of very fine droplets of size less than 15 mu m and large fuel ligaments associated with length scales of the order of 500 mu m and higher. For a constant pressure difference across the carburettor, the fuel consists of droplets with an SMD of the order of 30 mu m. Also, the effect of liquid fuel film on the cold start HC emissions is studied. Based on the understanding obtained from these studies, strategies such as manifold heating and varying carburettor main jet nozzle diameter are implemented. These are observed to reduce emissions under both idling and varying load conditions.

Differentially Selective Chemosensor with Fluorescence Off-On Responses on Cu2+ and Zn2+ Ions in Aqueous Media and Applications in Pyrophosphate Sensing, Live Cell Imaging, and Cytotoxicity

A new benzoyl hydrazone based chemosensor R is synthesized by Schiff base condensation of 2,6-diformyl-4-methylphenol and phenyl carbohydrazide and acts as a highly selective fluorescence sensor for Cu2+ and Zn2+ ions in aqueous media. The reaction of R with CuCl2 or ZnCl2 forms the corresponding dimeric dicopper(II) Cu-2(R)(CH3O)-(NO3)](2)(CH3O)(2) (R-Cu2+) and dizinc(1) Zn-2(R)(2)](NO3)(2) (R-Zn2+) complexes, which are characterized, as R, by conventional techniques including single-crystal X-ray analysis. Electronic absorption and fluorescence titration studies of R with different metal cations in a CH3CN/0.02 M HEPES buffer medium (pH = 7.3) show a highly selective binding affinity only toward Cu(2+)and Zn2+ ions even in the presence of other commonly coexisting ions such as Ne+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, and Hg2+. Quantification of the fluorescence titration analysis shows that the chemosensor R can indicate the presence of Cu2+ and Zn2+ even at very low concentrations of 17.3 and 16.5 ppb, respectively. R-Zn2+ acts as a selective metal-based fluorescent sensor for inorganic pyrophosphate ion (PPi) even in the presence of other common anions such as F-, Cl-, Br-, I-, CH3COO-, CO32-, HCO3-, N-3(-), SO42-, PPi, AMP, ADP, and ATP in an aqueous medium. The propensity of R as a bioimaging fluorescent probe to detect Cu2+ and Zn2+ ions in human cervical HeLa cancer cell lines and their cytotoxicity against human cervical (HeLa), breast cancer (MCF7), and noncancer breast epithelial (MCF10a) cells have also been investigated. R-Cu2+ shows better cytotoxicity and sensitivity toward cancer cells over noncancer cells than R and R-Zn2+ under identical conditions, with the appearance of apoptotic bodies.

Small strong epsilon nets

Let P be a set of n points in R-d. A point x is said to be a centerpoint of P if x is contained in every convex object that contains more than dn/d+1 points of P. We call a point x a strong centerpoint for a family of objects C if x is an element of P is contained in every object C is an element of C that contains more than a constant fraction of points of P. A strong centerpoint does not exist even for halfspaces in R-2. We prove that a strong centerpoint exists for axis-parallel boxes in Rd and give exact bounds. We then extend this to small strong epsilon-nets in the plane. Let epsilon(S)(i) represent the smallest real number in 0, 1] such that there exists an epsilon(S)(i)-net of size i with respect to S. We prove upper and lower bounds for epsilon(S)(i) where S is the family of axis-parallel rectangles, halfspaces and disks. (C) 2014 Elsevier B.V. All rights reserved.

Role of Cu2+ ions substitution in magnetic and conductivity behavior of nano-CoFe2O4

Cobalt copper ferrite nanopowders with composition Co1-xCu5Fe2O4 (0.0 <= x <= 0.5) was synthesized by solution combustion method. The powder X-ray diffraction studies reveal the formation of single ferrite phase with particle size of similar to 11-35 nm. Due to increase in electron density with in a material, X-ray density increase with increase of Cu2+ ions concentration. As Cu2+ ions concentration increases, saturation magnetization decreases from 38.5 to 26.7 emu g(-1). Further, the squareness ratio was found to be similar to 0.31-0.46 which was well below the typical value 1, which indicates the existence of single domain isolated ferrimagnetic samples. The dielectric and electrical modulus was studied over a frequency range of 1 Hz to 1 MHz at room temperature using the complex impedance spectroscopy technique. Impedance plots showed only one semi-circle which corresponds to the contributions of grain boundaries. The lower values of dielectric loss at higher frequency region may be quite useful for high frequency applications such as microwave devices. (C) 2014 Elsevier B.V. All rights reserved.

Rapid, microwave-assisted synthesis of Gd2O3 and Eu:Gd2O3 nanocrystals: characterization, magnetic, optical and biological studies

Ultra-small crystals of undoped and Eu-doped gadolinium oxide (Gd2O3) were synthesised by a simple, rapid microwave-assisted route, using benzyl alcohol as the reaction solvent. XRD, XPS and TEM analysis reveal that the as-prepared powder material consists of nearly monodisperse Gd2O3 nanocrystals with an average diameter of 5.2 nm. The nanocrystals show good magnetic behaviour and exhibit a larger reduction in relaxation time of water protons than the standard Gd-DTPA complex currently used in MRI imaging. Cytotoxicity studies (both concentration- and time-dependent) of the Gd2O3 nanocrystals show no adverse effect on cell viability, evidencing their high biological compatibility. Finally, Eu:Gd2O3 nanocrystals were prepared by a similar route and the red luminescence of Eu3+ activator ions was used to study the cell permeability of the nanocrystals. Red fluorescence from Eu3+ ions observed by fluorescence microscopy shows that the nanocrystals (Gd2O3 and Eu:Gd2O3) can permeate not only the cell membrane but can also enter the cell nucleus, rendering them candidate materials not only for MRI imaging but also for drug delivery when tagged or functionalized with specific drug molecules.

Digestive ripening and green synthesis of ultra-small (r < 2 nm) stable ZnO quantum dots

Given the recent reports pertaining to novel optical properties of ultra-small quantum dots (QDs) (r <2 nm), this nanomaterial is of relevance to both technology and science. However it is well known that in these size regimes most chalocogenide QD dispersions are unstable. Since applications often require use of QD dispersions (e.g. for deployment on a substrate), stabilizing these ultra-small particles is of practical relevance. In this work we demonstrate a facile, green, solution approach for synthesis of stable, ultra-small ZnO QDs having radius less than 2 nm. The particle size is calculated using Brits' equation and confirmed by transmission electron micrographs. ZnO QDs reported remain stable for > 120 days in ethanol (at similar to 298-303 K). We report digestive ripening (DR) in TEA capped ZnO QDs; this occurs rapidly over a short duration of 5 min. To explain this observation we propose a suitable mechanism based on the Lee's theory, which correlates the tendency of DR with the observed zeta potentials of the dispersed medium. To the best of our knowledge this is the (i) first report on DR in oxide QDs, as well as the first direct experimental verification of Lee's theory, and (ii) most rapid DR reported so far. The facile nature of the method presented here makes ultra-small ZnO readily accessible for fundamental exploration and technologically relevant applications. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.