Terpyridine Oxovanadium(IV) Complexes of Phenanthroline Bases for Cellular Imaging and Photocytotoxicity in HeLa Cells

Oxovanadium(IV) complexes VO(N-N-N)(N-N)](NO3)(2) (1-4) of (4'-phenyl)-2,2': 6',2 `'-terpyridine (ph-tpy in 1 and 2) or (4'-pyrenyl)-2,2':6',2 `'-terpyridine (py-tpy in 3 and 4) having N-N as 1,10-phenanthroline (phen in 1 and 3) or dipyrido3,2-a:2',3'-c]phenazine (dppz in 2 and 4) are prepared and characterized. The crystal structure of 1 has VO2+ group in VN5O coordination geometry. The terpyridine ligand coordinates in a meridional binding mode. The phen ligand displays a chelating mode of binding with an N-donor site trans to the vanadyl oxo group. The complexes show a d-d band in the range of 710-770 nm in aqueous DMF (4:1 v/v). The complexes exhibit an irreversible V-IV/V-III redox response near -1.0 V vs. SCE in aqueous DMF/0.1 M KCl. The complexes bind to CT DNA giving K-b values within 3.5 x 10(5) to 1.2 x 10(6) M-1. The complexes show poor chemical nuclease activity in dark. Complexes 2-4 show photonuclease activity in UV-A light of 365 nm forming O-1(2) and (OH)-O-center dot. Complex 4 shows DNA photocleavage activity at near-IR light of 785 nm forming (OH)-O-center dot radicals. Complexes 2 and 4 show significant photocytotoxicity in HeLa cancer cells. Uptake of the complexes in HeLa cells, studied by fluorescence imaging, show predominantly cytosolic localization inside the cells.

Preparation of the layered double hydroxide (LDH) LiAl2(OH)(7)center dot 2H(2)O, by gel to crystallite conversion and a hydrothermal method, and its conversion to lithium aluminates

A layered double hydroxide (LDH) with chemical composition LiAl2(OH)(7) . 2H(2)O was prepared via a wet chemical route of gel to crystallite (G-C) conversion at 80 degrees C involving the reaction of hydrated alumina gel, Al2O3.yH(2)O (80 < y < 120) with LiOH (Li2O/Al2O3 greater than or equal to 0.5) in presence of hydrophilic solvents such as ethanol under refluxing conditions. The hydrothermal synthesis was carried out using the same reactants by heating to less than or equal to 140 degrees C in a Teflon-lined autoclave under autogenerated pressure (less than or equal to 20 MPa). Transmission electron microscopy showed needle-shaped aggregates of size 0.04-0.1 mu m for the gel to crystallite conversion product, whereas the hydrothermal products consisted of individual lamellar crystallites of size 0.2-0.5 mu m with hexagonal morphology. The LDH prepared through the gel to crystallite conversion could be converted into LiAl(OH)(4) . H2O or LiAl(OH)(3)NO3 . H2O by imbibition of LiOH or LiNO3, respectively, under hydrothermal conditions. Thermal decomposition of LDH above 1400 degrees C gave rise to LiAl5O8 accompanied by the evaporation of Li2O. LiAl(OH)(4) . H2O and LiAl(OH)(3)NO3 . H2O decomposed in the temperature range 400-1000 degrees C to alpha- or beta-LiAlO2. The compositional dependence of the product, the intermediate phases formed during the heat treatment and the possible reactions involved are described in detail.

Charge Density Analysis of a Pentaborate Ion in an Ammonium Borate: Toward the Understanding of Topological Features in Borate Minerals

Structural and charge density distribution studies have been carried out on a single crystal data of an ammonium borate, [C(10)H(26)N(4)][B(5)O(6)(OH)(4)](2), synthesized by solvothermal method. Further, the experimentally observed geometry is used for the theoretical charge density calculations using the B3LYP/6-31G** level of theory, and the results are compared with the experimental values. Topological analysis of charge density based on the Atoms in Molecules approach for B-O bonds exhibit mixed covalent/ionic character. Detailed analysis of the hydrogen bonds in the crystal structure in the ammonium borate provides insights into the understanding of the reaction pathways that net atomic charges and electrostatic potential isosurfaces also give additional such systems. could result in the formation of borate minerals. The input to evaluate chemical and physical properties in such systems.

Usefulness of in Situ Single Crystal to Single Crystal Transformation (SCSC) Studies in Understanding the Temperature-Dependent Dimensionality Cross-over and Structural Reorganization in Copper-Containing Metal-Organic Frameworks (MOFs)

Two copper-containing compounds [Cu(3)(mu(3)-OH)(2)-(H(2)O)(2){(SO(3))-C(6)H(3)-(COO)(2)}(CH(3)COO)] , I, and [Cu(5)(mu(3)-OH)(2)(H(2)O)(6){(NO(2))-C(6)H(3)-(COO)(2)}(4)]center dot 5H(2)O, II, were prepared using sulphoisophthalic and nitroisophthalic acids. The removal of the coordinated water molecules in the compounds was investigated using in situ single crystal to single crystal (SCSC) transformation studies, temperature-dependent powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The efficacy of SCSC transformation studies were established by the observation of dimensionality cross-over from a two-dimensional (I) to a three-dimensional structure, Cu(6)(mu(3)-OH)(4){(SO(3))-C(6)H(3)-(COO)(2)}(2)(CH(3)COO)(2), Ia, during the removal of the coordinated water molecules. Compound H exhibited a structural reorganization forming Cu(5)(mu(2)-OH)(2){(NO(2))C(6)H(3)-(COO)(2))(4)], Ha, possessing trimeric (Cu(3)O(12)) and dimeric (Cu(2)O(8)) copper clusters. The PXRD studies indicate that the three-dimensional structure (Ia) is transient and unstable, reverting back to the more stable two-dimensional structure (I) on cooling to room temperature. Compound Ha appears to be more stable at room temperature. The rehydration/dehydration studies using a modified TGA setup suggest complete rehydration of the water molecules, indicating that the water molecules in both compounds are labile. A possible model for the observed changes in the structures has been proposed. Magnetic studies indicate changes in the exchanges between the copper centers in Ha, whereas no such behavior was observed in Ia.

Chain Length Effects on Helix-Hairpin Distribution in Short Peptides with Aib-(D)Ala and Aib-Aib Segments

The Aib-(D)Ala dipeptide segment has a tendency to form both type-I'/III' and type-I/III beta-turns. The occurrence of prime turns facilitates the formation of beta-hairpin conformations, while type-I/III turns can nucleate helix formation. The octapeptide Boc-Leu-Phe-Val-Aib-(D)Ala-Leu-Phe-Val-OMe (1) has been previously shown to form a beta-hairpin in the crystalline state and in solution. The effects of sequence truncation have been examined using the model peptides Boc-Phe-Val-Aib-Xxx-Leu-Phe-NHMe (2, 6), Boc-Val-Aib-Xxx-Leu-NHMe (3, 7), and Boc-Aib-Xxx-NHMe (4, 8), where Xxx = (D)Ala, Aib. For peptides with central Aib-Aib segments, Boc-Phe-Val-Aib-Aib-Leu-Phe-NHMe (6), Boc-Val-Aib-Aib-Leu-NHMe (7), and Boc-Aib-Aib-NHMe (8) helical conformations have been established by NMR studies in both hydrogen bonding (CD(3)OH) and non-hydrogen bonding (CDCl(3)) solvents. In contrast, the corresponding hexapeptide Boc-Phe-Val-Aib-(D)Ala-Leu-Phe-Val-NHMe (2) favors helical conformations in CDCl(3) and beta-hairpin conformations in CD(3)OH. The beta-turn conformations (type-I'/III) stabilized by intramolecular 4 -> 1 hydrogen bonds are observed for the peptide Boc-Aib-(D)Ala-NHMe (4) and Boc-Aib-Aib-NIiMe (8) in crystals. The tetrapeptide Boc-Val-Aib-Aib-Leu-NHMe (7) adopts an incipient 3(10)-helical conformation stabilized by three 4 -> 1 hydrogen bonds. The peptide Boc-Val-Aib-(D)Ala-Leu-NHMe (3) adopts a novel et-turn conformation, stabilized by three intramolecular hydrogen bonds (two 4 -> 1 and one 5 -> 1). The Aib-L(D)Ala segment adopts a type-I' beta-turn conformation. The observation of an NOE between Val (1) NH <-> HNCH(3) (5) in CD(3)OH suggests, that the solid state conformation is maintained in methanol solutions. (C) 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 744-756, 2011.

Generalization of the collision cone approach for motion safety in 3-D environments

Avoidance of collision between moving objects in a 3-D environment is fundamental to the problem of planning safe trajectories in dynamic environments. This problem appears in several diverse fields including robotics, air vehicles, underwater vehicles and computer animation. Most of the existing literature on collision prediction assumes objects to be modelled as spheres. While the conservative spherical bounding box is valid in many cases, in many other cases, where objects operate in close proximity, a less conservative approach, that allows objects to be modelled using analytic surfaces that closely mimic the shape of the object, is more desirable. In this paper, a collision cone approach (previously developed only for objects moving on a plane) is used to determine collision between objects, moving in 3-D space, whose shapes can be modelled by general quadric surfaces. Exact collision conditions for such quadric surfaces are obtained and used to derive dynamic inversion based avoidance strategies.

Synthesis of a mixed-metal spinel, NiMn2O4, through site-selective substitution in MOF, (NiMn2){C6H3(COO)(3)}(2)]: synthesis, structure and magnetic studies

A mixed-metal metal-organic framework (MOF) compound NiMn2{C6H3(COO)(3)}(2)], I, is prepared hydrothermally by replacing one of the octahedral Mn2+ ions in Mn-3{C6H3(COO)(3)}(2)] by Ni2+ ions. Magnetic studies on I suggest antiferromagnetic interactions with weak canted antiferromagnetism below 8 K. On heating in flowing air I transforms to NiMn2O4 spinel at low temperature (T < 400 degrees C). The thermal decomposition of I at different temperatures results in NiMn2O4 with particle sizes in the nano regime. The nanoparticle nature of NiMn2O4 was confirmed using PXRD and TEM studies. Magnetic studies on the nanoparticles of NiMn2O4 indicate ferrimagnetism. The transition temperature of NiMn2O4 nanoparticles exhibits a direct correlation with the particle size. This study highlights the usefulness of MOF compound as a single-source precursor for the preparation of important ceramic oxides with better control on the stoichiometry and particle size.

Influence of nature of support on the catalytic activity of supported molybdenum-oxo species in benzyl alcohol conversion

Supported catalysts containing 15 wt.% of molybdenum have been prepared by the incipient wetness impregnation method. CaO, MgO, Al2O3, Zr(OH)4 and Al(OH)3 have been used as supports for the preparation of supported Mo catalysts. Characterisation of all the materials prepared has been carried out through BET surface area measurement, X-ray diffractometry and FT-IR spectroscopy. Catalytic activity measurements have been carried out with reference to structure-sensitive benzyl alcohol conversion in the liquid phase. The percentage conversion of benzyl alcohol to benzaldehyde and toluene varied over a large range depending on the support used for the preparation of catalysts, indicating the importance of the support on catalytic activity of Mo catalysts. Al(OH)3 has been found to be the best support for molybdenum among all the supports used. Support–metal interaction (SMI) has been found to play an important role in determining the catalytic activity of supported catalysts.

Analysis on conservation of disulphide bonds and their structural features in homologous protein domain families

Background: Disulphide bridges are well known to play key roles in stability, folding and functions of proteins. Introduction or deletion of disulphides by site-directed mutagenesis have produced varying effects on stability and folding depending upon the protein and location of disulphide in the 3-D structure. Given the lack of complete understanding it is worthwhile to learn from an analysis of extent of conservation of disulphides in homologous proteins. We have also addressed the question of what structural interactions replaces a disulphide in a homologue in another homologue. Results: Using a dataset involving 34,752 pairwise comparisons of homologous protein domains corresponding to 300 protein domain families of known 3-D structures, we provide a comprehensive analysis of extent of conservation of disulphide bridges and their structural features. We report that only 54% of all the disulphide bonds compared between the homologous pairs are conserved, even if, a small fraction of the non-conserved disulphides do include cytoplasmic proteins. Also, only about one fourth of the distinct disulphides are conserved in all the members in protein families. We note that while conservation of disulphide is common in many families, disulphide bond mutations are quite prevalent. Interestingly, we note that there is no clear relationship between sequence identity between two homologous proteins and disulphide bond conservation. Our analysis on structural features at the sites where cysteines forming disulphide in one homologue are replaced by non-Cys residues show that the elimination of a disulphide in a homologue need not always result in stabilizing interactions between equivalent residues. Conclusion: We observe that in the homologous proteins, disulphide bonds are conserved only to a modest extent. Very interestingly, we note that extent of conservation of disulphide in homologous proteins is unrelated to the overall sequence identity between homologues. The non-conserved disulphides are often associated with variable structural features that were recruited to be associated with differentiation or specialisation of protein function.

A role for nocturnal serum testosterone surge in regulating spermatogenesis in the adult non-human primate

Adult male bonnet monkeys exhibit nychthemeral rhythms in testosterone (T) secretion but the precise role of this heightened level of T secretion in regulating spermatogenesis is not known. Intranasal administration of microdoses (500 mu g or 250 mu g/day) of Norethisterone (IN-NET) to adult monkeys (n = 6) at 1600 h each day selectively and completely suppressed the nocturnal surge levels of serum T. Concomitant with this was a significant reduction (P<0.01) in serum LH but not FSH levels. DNA flow cytometric analysis of testicular biopsy tissue showed by week 10 of IN-NET treatment an arrest in meiotic transformation of primary spermatocytes (4C) to round/elongate (1C/HC) spermatids and by week 20 there was a complete absence of 4C, 1C and HC cells (with a relative accumulation in 2C cells). The accumulated meiotic (4C) cells at week 10 showed an increase (>80%, P<0.01) in coefficient of variation and a decrease in intensity of DNA-bound ethidium bromide fluorescence, parameters characteristic of degenerating 'apoptotic' subpopulation of germ cells. While two monkeys exhibited acute oligozoospermia 4 became azoospermic by 20 weeks of IN-NET treatment. A complete, qualitative reversal in the regressive changes in spermatogenesis and near-normal sperm output were apparent at the end of a 20-week recovery phase. These data demonstrate that prolonged, selective suppression of nocturnal surge levels of serum T secretion exerts a primary effect on meiosis in spermatogenesis leading to oligo/azoospermic status in adult bonnet monkeys.

New approach to improved detection and tracking performance in track-while-scan radars. Part 1: Introduction and review

The paper presents a new approach to improve the detection and tracking performance of a track-while-scan (TWS) radar. The contribution consists of three parts. In Part 1 the scope of various papers in this field is reviewed. In Part 2, a new approach for integrating the detection and tracking functions is presented. It shows how a priori information from the TWS computer can be used to improve detection. A new multitarget tracking algorithm has also been developed. It is specifically oriented towards solving the combinatorial problems in multitarget tracking. In Part 3, analytical derivations are presented for quantitatively assessing, a priori, the performance of a track-while-scan radar system (true track initiation, false track initiation, true track continuation and false track deletion characteristics). Simulation results are also shown.

35Cl NQR in N3P3Cl4Ph2 and N3P3Cl4(NMe2)2

35Cl NQR has been investigated in two cyclotriphosphazene derivatives N3P3Cl4Ph2 and N3P3Cl4(NMe2)2. The observed frequencies are assigned to the various chlorines and the temperature variation of the NQR frequencies studied in the range from 77 K to 300 K. The results are analysed using the Bayer-Kushida-Brown approach. Torsional (librational) frequencies are found to fall in the range 10–25 cm−1 and are found to be only slightly temperature dependent.

The Structure Of 2',3'-O-Isopropylideneuridine

C12HI6N206 is orthorhombic, P2x2121, with a = 19.890 (5), b = 12.789 (2), c = 5.236 (1) A, Z = 4, U = 1331.9/~ 3, F(000) = 600. Mo Ka (/~ = 0.123 mm -1) intensities for 940 unique reflections up to sin 0/2 = 0.538/k -1 were collected on a CAD-4 diffractometer. Final R = 0.034. The glycosidic torsion angle 2~CN is 3"4 °, significantly smaller than that (56.5 °) in 2',3'- -methoxymethyleneuridine (MMU). The ribose moiety has a C(3')-exo-C(4')-endo twist conformation, in contrast to the C(2')-endo conformation in MMU. However, the maximum amplitudes of pucker for the ribose and dioxolane rings are very nearly the same for the two structures. The conformation about C(4')-C(5') is gauche-gauche (~0oo = -68-4, Ooc = 51.3°).

Thermal decomposition of doped calcium hydroxide for chemical energy storage

Thermal decomposition of Ca(OH)2 with and without additives has been experimentally investigated for its application as a thermochemical energy storage system. The homogeneous reaction model gives a satisfactory fit for the kinetic data on pure and Ni(OH)2---, Zn(OH)2--- and Al(OH)3---doped Ca(OH)2 and the order of reaction is 0.76 in all cases except for the Al(OH)3-doped sample for which the decomposition is zero order. These additives are shown not only to enhance the reaction rate but also to reduce the decomposition temperature significantly. Some models for solid decomposition reactions, and possible mechanisms in the decomposition of solids containing additives, are also discussed.