Substitution-Modulated Anticancer Activity of Half-Sandwich Ruthenium(II) Complexes with Heterocyclic Ancillary Ligands

Ten new organometallic half-sandwich ruthenium complexes with heterocyclic ligands have been synthesized (H1-H10). The substituents on the ancillary heterocyclic ligands were varied to understand the effect of substitution on anticancer activity. The crystallographic characterization of five complexes confirms that they adopt three-legged piano-stool structures and are stabilized by intramolecular hydrogen bonding. Complexes H2 and H3 also exhibit halogen bonding in the solid state. In aqueous media, the complexes form dinuclear ruthenium species. Complex H1 with a noncytotoxic heterocycle, 6-fluoro-2-mercaptobenzothiazole, and complex H11 with the unsubstituted 2-mercaptobenzothiazole are the most active against A2780 and KB cell lines. The substitution of the H atoms on the ancillary ligand with Cl or Br atoms leads to a decrease in the anticancer activity. With the exception of fluorine-substituted H5, the complexes with mercaptobenzoxazole (H6-H9) are inactive against all of the tested cell lines. Ruthenium complexes with mercaptonaphthimidazole (H10) and mercaptobenzimidazole (H13) do not show any anticancer activity. The active complexes show a biphasic melting curve when incubated with calf thymus (CT) DNA. These complexes only inhibit thioredoxin reductase (TrxR) enzyme activity to a small extent. The substitution of hydrogen atoms with fluorine atoms in the aromatic heterocyclic ligands on organometallic half-sandwich ruthenium complexes has the most beneficial effect on their anticancer activity.

Biodegradation of acrylamide by acrylamidase from Stenotrophomonas acidaminiphila MSU12 and analysis of degradation products by MALDI-TOF and HPLC

The present study examines an improved detoxification and rapid biological degradation of toxic pollutant acrylamide using a bacterium. The acrylamide degrading bacterium was isolated from the soil followed by its screening to know the acrylamide degrading capability. The minimal medium containing acrylamide (30 mM) served as a sole source of carbon and nitrogen for their active growth. The optimization of three different factors was analyzed by using Response Surface Methodology (RSM). The bacteria actively degraded the acrylamide at a temperature of 32 degrees C, with a maximum growth at 30 mM substrate (acrylamide) concentration at a pH of 7.2. The acrylamidase activity and degradation of acrylamide was determined by High Performance Liquid Chromatography (HPLC) and Matrix Assisted Laser Desorption and Ionization Time of Flight mass spectrometer (MALDI-TOF). Based on 168 rRNA analysis the selected strain was identified as Gram negative bacilli Stenotrophomonas acidaminiphila MSU12. The acrylamidase was isolated from bacterial extract and was purified by HPLC, whose mass spectrum showed a molecular mass of 38 kDa. (C) 2014 Elsevier Ltd. All rights reserved.

Finite element simulations of notch tip fields in magnesium single crystals

Recent experiments using three point bend specimens of Mg single crystals have revealed that tensile twins of {10 (1) over bar2}-type form profusely near a notch tip and enhance the fracture toughness through large plastic dissipation. In this work, 3D finite element simulations of these experiments are carried out using a crystal plasticity framework which includes slip and twinning to gain insights on the mechanics of fracture. The predicted load-displacement curves, slip and tensile twinning activities from finite element analysis corroborate well with the experimental observations. The numerical results are used to explore the 3D nature of the crack tip stress, plastic slip and twin volume fraction distributions near the notch root. The occurrence of tensile twinning is rationalized from the variation of normal stress ahead of the notch tip. Further, deflection of the crack path at twin-twin intersections observed in the experiments is examined from an energy standpoint by modeling discrete twins close to the notch root.

Strength and Deformation Characteristics of Fly Ash Mixed with Randomly Distributed Plastic Waste

In order to explore the potential use of fly ash and plastic waste in bulk quantities in civil engineering applications, it is necessary to understand the behavior of fly ash and fly ash mixed with plastic waste. These materials are considered as wastes and in this study, it is shown that combination of fly ash and plastic waste is very useful. In this regard, various tests such as classification tests, unconfined compressive strength and compressibility tests, consolidated undrained tests, and California bearing ratio tests were conducted. The results indicated that the inclusion of plastic waste in fly ash is effective in improving the engineering properties of fly ash in terms of compressive strength, shear strength parameters, and CBR values. In order to understand the effect of sample size on the shear strength parameters of fly ash and fly ash mixed with plastic waste, consolidated undrained tests were conducted with sample sizes of 38x76mm and 50x100mm. The results of the tests indicate that the shear strength increases with the increase in sample size. The implication of the use of fly ash mixed with plastic waste in unpaved roads is presented in terms of reduction of carbon print.

Seleno-Nucleobases and Their Water-Soluble Ruthenium-Arene Half-Sandwich Complexes: Chemistry and Biological Activity

Half-sandwich organometallic ruthenium complexes of seleno-nucleobases, 3 and 4, were synthesized and characterized. The structures of both complexes were determined by X-ray crystallography and are the first crystal structures of ruthenium complexes with seleno-nucleobases. Interestingly, 3 self-assembles aided by adventitious water in DMF to give a tetranuclear square 3a center dot 6H(2)O. Complex 4 is active against Jurkat and Molt-4 cell lines but inactive against the K562 cell line, whereas 3 is completely inactive against all three cell lines. The free ligand 6-selenopurine (1) and 6-selenoguanine (2) are highly active against these cell lines. Compound 2, like its thio analogue, is unstable under UVA light, whereas 4 is stable under similar conditions, which suggests that the ruthenium complex could reduce problems associated with the instability of the free ligand, 2, under irradiation.

Differential Multi-phase DLL for Reconfigurable Radio Frequency Synthesizer

A multi phase, delay-locked loop (DLL) based frequency synthesizer is designed for harmonic rejection mixing in reconfigurable radios. This frequency synthesizer uses a 1 GHz input reference frequency, and achieves <= 20ns settling time by utilizing a wide loop bandwidth. The circuit has been designed in 0.13-mu m CMOS technology. It is designed for a frequency range of 500 MHz to 3 GHz with stuck/harmonic lock removal assist. Index Terms-stuck lock, harmonic lock, delay-locked loops, multi phase, phase detector, frequency synthesis

Membrane-based deformable mirror: intrinsic aberrations and alignment issues

A deformable mirror (DM) is an important component of an adaptive optics system. It is known that an on-axis spherical/parabolic optical component, placed at an angle to the incident beam introduces defocus as well as astigmatism in the image plane. Although the former can be compensated by changing the focal plane position, the latter cannot be removed by mere optical realignment. Since the DM is to be used to compensate a turbulence-induced curvature term in addition to other aberrations, it is necessary to determine the aberrations induced by such (curved DM surface) an optical element when placed at an angle (other than 0 deg) of incidence in the optical path. To this effect, we estimate to a first order the aberrations introduced by a DM as a function of the incidence angle and deformation of the DM surface. We record images using a simple setup in which the incident beam is reflected by a 37 channel micro-machined membrane deformable mirror for various angles of incidence. It is observed that astigmatism is a dominant aberration, which was determined by measuring the difference between the tangential and sagittal focal planes. We justify our results on the basis of theoretical simulations and discuss the feasibility of using such a system for adaptive optics considering a trade-off between wavefront correction and astigmatism due to deformation. (C) 2015 Optical Society of America

First hyperpolarizability of Ru-half-sandwich complexes: The effect of halogen atom substitution on the ancillary ligand

The first hyperpolarizability (beta) of a series of half-sandwich Ru complexes with a mercaptobenzothiazole ligand bearing a halogen atom substitution in the para-position has been investigated by hyper-Rayleigh scattering and quantum chemical calculations. The heterocyclic ligand with a bromine atom in the para position makes it a very good donor and charge flows to the Ru center enhancing the beta value of the complex by a factor of 2 compared to the complex with the ligand without the halogen substitution. The resonance (+R) and the inductive (-I) effects exerted by the halogen atom in the para position push electrons in opposing directions in the complex. For the Br and Cl atoms the resonance effect dominates which enables the ligand to donate electrons to the metal center thereby increasing the hyperpolarizability whereas for the fluorine atom, the inductive effect is dominant which reduces the charge flow to the metal and the hyperpolarizability drops even below that of the unsubstituted ligand. This unprecedented halogen atom effect on beta of metal complexes is reported. (C) 2015 Elsevier By. All rights reserved.

Gray to transmissive electrochromic switching based on electropolymerized PEDOT-ionic liquid functionalized graphene films

A supporting electrolyte based on lithium perchlorate has been functionalized with graphene (ionic liquid functionalized graphene (IFGR)) by facile electrochemical exfoliation of graphite rods in aq. LiClO4 solution. Poly(3,4-ethylenedioxythiophene) (PEDOT)-IFGR films were prepared by electropolymerization of EDOT monomer with IFGR as supporting electrolyte in ethanol at static potential of 1.5 V. The Raman, SEM, and XPS analysis of PEDOT-IFGR film confirmed the presence of functionalized graphene in the film. The PEDOT-IFGR films showed good electrochemical properties, better ionic and electrical conductivity, significant band gap, and excellent spectroelectrochemical and electrochromic properties. The electrical conductivity of PEDOT-IFGR film was measured as about 3968 S cm(-1). PEDOT-IFGR films at reduced state showed strong and broad absorption in the whole visible region and remarkable absorption at near-IR region. PEDOT-IFGR film showed electrochromic response between transmissive blue and darkish gray at redox potential. The color contrast (%T) between fully reduced and oxidized states of PEDOT-IFGR film is 25 % at lambda (max) of 485 nm. The optical switching stability of PEDOT-IFGR film has retained 80 % of its electroactivity even after 500 cycles.

Remarkable Effect of Chalcogen Substitution on an Enzyme Mimetic for Deiodination of Thyroid Hormones

Iodothyronine deiodinases are selenoenzymes which regulate the thyroid hormone homeostasis by catalyzing the regioselective deiodination of thyroxine (T4). Synthetic deiodinase mimetics are important not only to understand the mechanism of enzyme catalysis, but also to develop therapeutic agents as abnormal thyroid hormone levels have implications in different diseases, such as hypoxia, myocardial infarction, critical illness, neuronal ischemia, tissue injury, and cancer. Described herein is that the replacement of sulfur/selenium atoms in a series of deiodinase mimetics by tellurium remarkably alters the reactivity as well as regioselectivity toward T4. The tellurium compounds reported in this paper represent the first examples of deiodinase mimetics which mediate sequential deiodination of T4 to produce all the hormone derivatives including T0 under physiologically relevant conditions.

The influence of reduced oxygen availability on gene expression in laboratory (H37Rv) and clinical strains (S7 and S10) of Mycobacterium tuberculosis

Mycobacterium tuberculosis has the ability to persist within the host in a dormant stage. One important condition believed to contribute to dormancy is reduced access to oxygen known as hypoxia. However, the response of M. tuberculosis to such hypoxia condition is not fully characterized. Virtually all dormant models against tuberculosis tested in animals used laboratory strain H37Rv or Erdman strain. But major outbreaks of tuberculosis (TB) occur with the strains that have widely different genotypes and phenotypes compared to H37Rv. In this study, we used a custom oligonucleotide microarray to determine the overall transcriptional response of laboratory strain (H37Rv) and most prevalent clinical strains (S7 and S10) of M. tuberculosis from South India to hypoxia. Analysis of microarray results revealed that a total of 1161 genes were differentially regulated (>= 1.5 fold change) in H37Rv, among them 659 genes upregulated and 502 genes down regulated. Microarray data of clinical isolates showed that a total of 790 genes were differentially regulated in S7 among which 453 genes were upregulated and 337 down regulated. Interestingly, numerous genes were also differentially regulated in S10 (total 2805 genes) of which 1463 genes upregulated and 1342 genes down regulated during reduced oxygen condition (Wayne's model). One hundred and thirty-four genes were found common and upregulated among all three strains (H37Rv, S7, and S10) and can be targeted for drug/vaccine development against TB. (C) 2015 Published by Elsevier B.V.

Spectral characterizations and photophysical properties of one-step synthesized blue fluorescent 4 `-aryl substituted 2,2 `:6 `,2 `'-terpyridine for OLEDs application

We have synthesized a series of 4'-aryl substituted 2,2':6',2 `'-terpyridine (terpy) derivatives, namely 4'-(4-methylphenyl)-2,2':6',2 `'-terpyridine (C-1), 4'-(2-furyl)-2,2':6'2 `'-terpyridine (C-2), and 4'-(3,4,5-trimethoxyphenyl)-2,2':6',2 `'-terpyridine (C-3). The synthesized terpy compounds were characterized by elemental analyses, FTIR, NMR (H-1 and C-13), and ESI-Mass spectrometry. Photophysical, electrochemical and thermal properties of terpy compounds were systematically studied. Maximum excitation band was observed between 240 and 330 nm using UV-visible spectra, and maximum emission peaks from PL spectra were observed at 385, 405 and 440 nm for C-1, C-2 and C-3 respectively. Fluorescence lifetime (tau) of the fluorophores was found to be 035 and 1.55 ns at the excitation wavelength of 406 nm for C-1 and C-2 respectively, and tau value for C-3 was found to be 0.29 ns at the excitation wavelength of 468 nm. We noticed that the calculated values of HOMO energy levels were increased from 5.96 (C-1) to 6.08 (C-3) eV, which confirms that C-3 derivative is more electrons donating in nature. The calculated electrochemical band gaps were 2.95, 2.82 and 3.02 eV for C-1, C-2 and C-3 respectively. These blue fluorescent emitter derivatives can be used as an electron transport and electroluminescent material to design the blue fluorescent organic light emitting diode (OLED) applications. (C) 2015 Elsevier B.V: All rights reserved.