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Sample records for forms non-selective cation

  1. The non-selective monovalent cationic channels TRPM4 and TRPM5.

    Science.gov (United States)

    Guinamard, Romain; Sallé, Laurent; Simard, Christophe

    2011-01-01

    Transient Receptor Potential (TRP) proteins are non-selective cationic channels with a consistent Ca(2+)-permeability, except for TRPM4 and TRPM5 that are not permeable to this ion. However, Ca(2+) is a major regulator of their activity since both channels are activated by a rise in internal Ca(2+). Thus TRPM4 and TRPM5 are responsible for most of the Ca(2+)-activated non-selective cationic currents (NSC(Ca)) recorded in a large variety of tissues. Their activation induces cell-membrane depolarization that modifies the driving force for ions as well as activity of voltage gated channels and thereby strongly impacts cell physiology. In the last few years, the ubiquitously expressed TRPM4 channel has been implicated in insulin secretion, the immune response, constriction of cerebral arteries, the activity of inspiratory neurons and cardiac dysfunction. Conversely, TRPM5 whose expression is more restricted, has until now been mainly implicated in taste transduction.

  2. Non-selective cation channels and oxidative stress- induced cell swelling

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    FELIPE SIMON

    2002-01-01

    Full Text Available Necrosis is considered as a non-specific form of cell death that induces tissue inflammation and is preceded by cell swelling. This increase in cell volume has been ascribed mainly to defective outward pumping of Na+ caused by metabolic depletion and/or to increased Na+ influx via membrane transporters. A specific mechanism of swelling and necrosis driven by the influx of Na+ through nonselective cation channels has been recently proposed (Barros et al., 2001a. We have characterized further the properties of the nonselective cation channel (NSCC in HTC cells. The NSCC shows a conductance of ~18 pS, is equally permeable to Na+ and K+, impermeant to Ca2+, requires high intracellular Ca2+ as well as low intracellular ATP for activation and is inhibited by flufenamic acid. Hydrogen peroxide induced a significant increase in cell volume that was dependent on external Na+. We propose that the NSCC, which is ubiquitous though largely inactive in healthy cells, becomes activated under severe oxidative stress. The ensuing Na+ influx initiates via positive feedback a series of metabolic and electrolytic disturbances, resulting in cell death by necrosis

  3. Importance of non-selective cation channel TRPV4 interaction with cytoskeleton and their reciprocal regulations in cultured cells.

    Directory of Open Access Journals (Sweden)

    Chandan Goswami

    non-selective cation channels and cytoskeleton at multiple levels. These cross talks may help us to understand the molecular basis of the Taxol-induced neuropathic pain development commonly observed in cancer patients.

  4. Differential effects of lysophosphatidylcholine and ACh on muscarinic K(+),non-selective cation and Ca(2+) currents in guinea-pig atrial cells.

    Science.gov (United States)

    Li, Libing; Matsuoka, Isao; Sakamoto, Kazuho; Kimura, Junko

    2016-06-08

    We compared the effects of lysophosphatidylcholine (LPC) and acetylcholine (ACh) on IK(ACh), ICa and a non-selective cation current (INSC) in guinea-pig atrial myocytes to clarify whether LPC and ACh activate similar Gi/o-coupled effector systems. IK(ACh), ICa and INSC were analyzed in single atrial myocytes by the whole cell patch-clamp. LPC induced INSC in a concentration-dependent manner in atrial cells. ACh activated IK(ACh), but failed to evoke INSC. LPC also activated IK(ACh) but with significantly less potency than ACh. The effects of both ligands on IK(ACh) were inhibited by intracellular loading of pre-activated PTX. This treatment also inhibited LPC-induced INSC, indicating that IK(ACh) and INSC induced by LPC are both mediated by Gi/o. LPC and ACh had similar potencies in inhibiting ICa, which was pre-augmented by forskolin, indicating that LPC and ACh activate similar amounts of α-subunits of Gi/o. The different effects of LPC and ACh on IK(ACh) and INSC may suggest that LPC and ACh activate Gi/o having different types of βγ subunits, and that LPC-induced INSC may be mediated by βγ subunits of Gi/o, which are less effective in inducing IK(ACh).

  5. Differential effects of lysophosphatidylcholine and ACh on muscarinic K+, non-selective cation and Ca2+ currents in guinea-pig atrial cells

    Science.gov (United States)

    Li, Libing; Matsuoka, Isao; Sakamoto, Kazuho; Kimura, Junko

    2016-01-01

    Abstract We compared the effects of lysophosphatidylcholine (LPC) and acetylcholine (ACh) on IK(ACh), ICa and a non-selective cation current (INSC) in guinea-pig atrial myocytes to clarify whether LPC and ACh activate similar Gi/o-coupled effector systems. IK(ACh), ICa and INSC were analyzed in single atrial myocytes by the whole cell patch-clamp. LPC induced INSC in a concentration-dependent manner in atrial cells. ACh activated IK(ACh), but failed to evoke INSC. LPC also activated IK(ACh) but with significantly less potency than ACh. The effects of both ligands on IK(ACh) were inhibited by intracellular loading of pre-activated PTX. This treatment also inhibited LPC-induced INSC, indicating that IK(ACh) and INSC induced by LPC are both mediated by Gi/o. LPC and ACh had similar potencies in inhibiting ICa, which was pre-augmented by forskolin, indicating that LPC and ACh activate similar amounts of α-subunits of Gi/o. The different effects of LPC and ACh on IK(ACh) and INSC may suggest that LPC and ACh activate Gi/o having different types of βγ subunits, and that LPC-induced INSC may be mediated by βγ subunits of Gi/o, which are less effective in inducing IK(ACh). PMID:26911304

  6. ACh-induced depolarization in inner ear artery is generated by activation of a TRP-like non-selective cation conductance and inactivation of a potassium conductance.

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    Ma, Ke-Tao; Guan, Bing-Cai; Yang, Yu-Qin; Zhao, Hui; Jiang, Zhi-Gen

    2008-05-01

    Adequate cochlear blood supply by the spiral modiolar artery (SMA) is critical for normal hearing. ACh may play a role in neuroregulation of the SMA but several key issues including its membrane action mechanisms remain poorly understood. Besides its well-known endothelium-dependent hyperpolarizing action, ACh can induce a depolarization in vascular cells. Using intracellular and whole-cell recording techniques on cells in guinea pig in vitro SMA, we studied the ionic mechanism underlying the ACh-depolarization and found that: (1) ACh induced a DAMP-sensitive depolarization when intermediate conductance KCa channels were blocked by charybdotoxin or nitrendipine. The ACh-depolarization was associated with a decrease in input resistance (R(input)) in high membrane potential (V(m)) ( approximately -40 mV) cells but with no change or an increase in R input in low Vm ( approximately -75 mV) cells. ACh-depolarization was attenuated by background membrane depolarization from approximately -70 mV in the majority of cells; (2) ACh-induced inward current in smooth muscle cells embedded in a SMA segment often showed a U-shaped I/V curve, the reversal potential of its two arms being near EK and 0 mV, respectively; (3) ACh-depolarization was reduced by low Na+, zero K+ or 20mM K+ bath solutions; (4) ACh-depolarization was inhibited by La3+ in all cells tested, by 4-AP and flufenamic acid in low Vm cells, but was not sensitive to Cd2+, Ni2+, nifedipine, niflumic acid, DIDS, IAA94, linopirdine or amiloride. We conclude that ACh-induced vascular depolarization was generated mainly by activation of a TRP-like non-selective cation channel and by inactivation of an inward rectifier K+ channel.

  7. A cell shrinkage-induced non-selective cation conductance with a novel pharmacology in Ehrlich-Lettre-ascites tumour cells

    DEFF Research Database (Denmark)

    Lawonn, Peter; Hoffmann, Else K; Hougaard, Charlotte

    2003-01-01

    In whole-cell recordings on Ehrlich-Lettre-ascites tumour (ELA) cells, the shrinkage-induced activation of a cation conductance with a selectivity ratio P(Na):P(Li):P(K):P(choline):P(NMDG) of 1.00:0.97:0.88:0.03:0.01 was observed. In order of potency, this conductance was blocked by Gd(3+)=benzam......-sensitive and -insensitive channels. In addition, because of its pharmacological profile, it may possibly be related to epithelial Na+ channels (ENaCs)....

  8. Solubilization of Phenol Derivatives in Polymer Micelles Formed by Cationic Block Copolymer

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    Irma Fuentes

    2017-01-01

    Full Text Available The aggregation of cationic block copolymers formed by polystyrene (PS and poly(ethyl-4-vinylpyridine (PS-b-PE4VP was studied in aqueous solution. Diblock copolymers of PS and poly(4-vinylpyridine were synthesized by sequential anionic polymerization using BuLi as initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PS-b-PE4VP block copolymers with different quaternization degree. The self-aggregation of cationic block copolymers was studied by fluorescence probing, whereas the morphology and size of polymer micelles were determined by transmission electronic microscopy. Results indicate that spherical micelles with sizes lower than 100 nm were formed, whereas their micropolarity decreases with increasing quaternization degree. The partition of phenols between the micellar and aqueous phase was studied by using the pseudo-phase model, and the results show that the partition coefficients increase with increasing length of the side alkyl chain and are larger for star micelles. These results are discussed in terms of three-region model.

  9. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  10. Bond-forming reactions of small triply charged cations with neutral molecules.

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    Fletcher, James D; Parkes, Michael A; Price, Stephen D

    2013-08-12

    Time-of-flight mass spectrometry reveals that atomic and small molecular triply charged cations exhibit extensive bond-forming chemistry, following gas-phase collisions with neutral molecules. These experiments show that at collision energies of a few eV, I(3+) reacts with a variety of small molecules to generate molecular monocations and molecular dications containing iodine. Xe(3+) and CS2(3+) react in a similar manner to I(3+), undergoing bond-forming reactions with neutrals. A simple model, involving relative product energetics and electrostatic interaction potentials, is used to account for the observed reactivity. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. ESR and electronic spectra of alkane radical cations formed in γ-irradiated 3-methylpentane and 3-methylhexane glasses containing alkane solutes

    International Nuclear Information System (INIS)

    Ichikawa, T.; Ohta, N.

    1987-01-01

    Electron spin resonance (ESR) and optical difference spectra of photobleaching are measured, and the radical cations from some higher alkanes (C 9 -C 11 ) and some methyl-branched butanes are found to be trapped in 3-methylpentane or 3-methylhexane matrices at 77 K. The ESR spectra show close agreement with those of radical cations produced in CCl 2 FCClF 2 matrices. The cations of methyl-branched butanes give the absorption bands with λ/sub max/ ranging from 300 to 260 nm and the bands are attributed to σ-localized cations, while the higher alkane cation bands appearing in the near-IR region are ascribed to σ-delocalized cations. The cations of higher alkanes are found to be mobilized by light with λ > 900 nm to recombine with the negative ions formed by electron scavenging

  12. DFT study of the electronic structure of anthracene derivatives in their neutral, anion and cation forms

    International Nuclear Information System (INIS)

    Kukhta, A V; Kukhta, I N; Kukhta, N A; Neyra, O L; Meza, E

    2008-01-01

    Anthracene and its simplest derivatives with electron-accepting (anthraquinone) and electron-donating (diaminoanthracene) properties in their anionic, neutral and cationic charge states are investigated using the density functional theory. The effect of addition and removal of the electron on the bond lengths, atomic charges, frontier orbitals, ionization potential (IP), electron affinity (EA) and reorganization energy is considered. The computed IP, EA and optical gaps are in rather good agreement with available experimental data.

  13. A solid-state cation exchange reaction to form multiple metal oxide heterostructure nanowires.

    Science.gov (United States)

    Chen, Y H; Huang, C W; Yeh, P H; Chen, J Y; Lin, T Y; Chang, C F; Wu, W W

    2016-09-29

    Metal oxide nanostructures have been investigated extensively due to their wide range of physical properties; zinc oxide is one of the most promising materials. It exhibits fascinating functional properties and various types of morphologies. In particular, ZnO heterostructures have attracted great attention because their performance can be modified and further improved by the addition of other materials. In this study, we successfully transformed ZnO nanowires (NWs) into multiple ZnO/Al 2 O 3 heterostructure NWs via a solid-state cation exchange reaction. The experiment was carried out in situ via an ultrahigh vacuum transmission electron microscope (UHV-TEM), which was equipped with a video recorder. Moreover, we analyzed the structure and composition of the heterostructure NWs by Cs-corrected STEM equipped with EDS. Based on these experimental results, we inferred a cation exchange reaction ion path model. Additionally, we investigated the defects that appeared after the cation reaction, which resulted from the remaining zinc ions. These multiple heterostructure ZnO/Al 2 O 3 NWs exhibited excellent UV sensing sensitivity and efficiency.

  14. Characterization of the nanostructure of complexes formed by single- or double-stranded oligonucleotides with a cationic surfactant.

    Science.gov (United States)

    Liu, Xiaoyang; Abbott, Nicholas L

    2010-12-02

    We report the use of dynamic light scattering (DLS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) to characterize the nanostructure of complexes formed by either single- or double-stranded oligonucleotides with a cationic surfactant (cetyltrimethylammonium bromide, CTAB) in aqueous solution (1 mM Li(2)SO(4)). For single-stranded oligonucleotides 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', both the appearance of two Bragg peaks (at 0.14 and 0.28 Å(-1)) in SAXS spectra with a spacing of 1:2 and form factor fits to SANS spectra are consistent with the presence of multilamellar vesicles (with, on average, 6-9 layers with a periodicity of 45-48 Å). Some samples showed evidence of an additional Bragg peak (at 0.20 Å(-1)) associated with periodic packing (with a periodicity of 31 Å) of the oligonucleotides within the lamellae of the nanostructure. The nucleotide composition of the single-stranded oligonucleotides was also found to impact the number and size of the complexes formed with CTAB. In contrast to 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', 5'-T(20)-3' did not change the state of aggregation of CTAB (globular micelles) over a wide range of oligonucleotide:CTAB charge ratios. These results support the proposition that hydrophobic interactions, as well as electrostatics, play a central role in the formation of complexes between cationic amphiphiles and single-stranded oligonucleotides and thus give rise to nanostructures that depend on nucleotide composition. In contrast to the single-stranded oligonucleotides, for double-stranded oligonucleotides mixed with CTAB, three Bragg peaks (0.13, 0.23, and 0.25 Å(-1)) in SAXS spectra with a spacing ratio of 1:√3:√4 and characteristic changes in SANS spectra indicate formation of a hexagonal nanostructure. Also, the composition of the double-stranded oligonucleotides did not measurably impact the nanostructure of complexes formed with CTAB, suggesting that electrostatic

  15. Characterization of a C-type natriuretic peptide (CNP-39)-formed cation-selective channel from platypus (Ornithorhynchus anatinus) venom

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    Kourie, Joseph I

    1999-01-01

    The lipid bilayer technique is used to characterize the biophysical and pharmacological properties of a novel, fast, cation-selective channel formed by incorporating platypus (Ornithorhynchus anatinus) venom (OaV) into lipid membranes.A synthetic C-type natriuretic peptide OaCNP-39, which is identical to that present in platypus venom, mimics the conductance, kinetics, selectivity and pharmacological properties of the OaV-formed fast cation-selective channel. The N-terminal fragment containing residues 1-17, i.e. OaCNP-39(1-17), induces the channel activity.The current amplitude of the TEACl-insensitive fast cation-selective channel is dependent on cytoplasmic K+, [K+]cis. The increase in the current amplitude, as a function of increasing [K+]cis, is non-linear and can be described by the Michaelis-Menten equation. At +140 mV, the values of γmax and KS are 63·1 pS and 169 mM, respectively, whereas at 0 mV the values of γmax and KS are 21·1 pS and 307 mM, respectively. γmax and KS are maximal single channel conductance and concentration for half-maximal γ, respectively. The calculated permeability ratios, PK:PRb:PNa: PCs:PLi, were 1:0·76:0·21:0·09:0·03, respectively.The probability of the fast channel being open, Po, increases from 0·15 at 0 mV to 0·75 at +140 mV. In contrast, the channel frequency, Fo, decreases from 400 to 180 events per second for voltages between 0 mV and +140. The mean open time, To, increases as the bilayer is made more positive, between 0 and +140 mV. The mean values of the voltage-dependent kinetic parameters, Po, Fo, To and mean closed time (Tc), are independent of [KCl]cis between 50 and 750 mM (P > 0·05).It is proposed that some of the symptoms of envenomation by platypus venom may be caused partly by changes in cellular functions mediated via the OaCNP-39-formed fast cation-selective channel, which affects signal transduction. PMID:10381585

  16. Nanostructure of polyplexes formed between cationic diblock copolymer and antisense oligodeoxynucleotide and its influence on cell transfection efficiency.

    Science.gov (United States)

    Zhao, Xiubo; Pan, Fang; Zhang, ZhuoQi; Grant, Colin; Ma, YingHua; Armes, Steven P; Tang, YiQing; Lewis, Andrew L; Waigh, Thomas; Lu, Jian R

    2007-11-01

    Although various cationic polymers have been used to condense anionically charged DNA to improve their transfection efficiency, there is still a lack of fundamental understanding about how to control the nanostructure and charge of the polyplexes formed and how to relate such information to cell transfection efficiency. In this work, we have synthesized a weak cationic and phosphorylcholine-containing diblock copolymer and used it as a model vector to deliver an antisense oligodeoxynucleotide (ODN) into HeLa cells. Small angle neutron scattering (SANS) was used to determine the copolymer/ODN polyplex structure. The SANS data revealed the formation of polyplex nanocylinders at high copolymer (N)/ODN (P) charge ratios, where N symbolizes the amine groups on the copolymer and P symbolizes the phosphate groups. However, the cylindrical lengths remained constant, indicating that the ODN binding over this region did not alter the cylindrical shape of the copolymer in solution. As the N/P ratio decreased and became close to unity the polyplex diameters remained constant, but their lengths increased substantially, suggesting the end-to-end bridging by ODN binding between copolymer cylinders. As the N/P ratios went below unity (with ODN in excess), the polyplex diameters increased substantially, indicating different ODN bridging to bundle the small polyplexes together. Transfection studies from HeLa cells indicated a steady increase in transfection efficiency with increasing cationic charge and decreasing polyplex size. Cell growth inhibition assay showed significant growth inhibition by the polyplexes coupled with weak cytotoxicity, indicating effective ODN delivery. While this study has confirmed the overall charge effect, it has also revealed progressive structural changes of the polyplexes against varying charge ratio, thereby providing useful insight into the mechanistic process behind the ODN delivery.

  17. Characterization of the nanostructure of complexes formed by a redox-active cationic lipid and DNA.

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    Pizzey, Claire L; Jewell, Christopher M; Hays, Melissa E; Lynn, David M; Abbott, Nicholas L; Kondo, Yukishige; Golan, Sharon; Talmon, Yeshayahu

    2008-05-08

    We report characterization of the nanostructures of complexes formed between the redox-active lipid bis(n-ferrocenylundecyl)dimethylammonium bromide (BFDMA) and DNA using small-angle neutron scattering (SANS) and cryogenic transmission electron microscopy (cryo-TEM). A particular focus was directed to the influence of lipid oxidation state (where reduced BFDMA has a net charge of +1 and oxidized BFDMA has a charge of +3) on the nanostructures of the solution aggregates formed. Complexes were characterized over a range of charge ratios of reduced BFDMA to DNA (1.1:1, 2.75:1, and 4:1) in solutions of 1 mM Li2SO4. For these complexes, a single peak in the SANS data at 1.2 nm(-1) indicated that a nanostructure with a periodicity of 5.2 nm was present, similar to that observed with complexes of the classical lipids DODAB/DOPE and DNA (multilamellar spacing of 7.0 nm). The absence of additional Bragg peaks in all the SANS data indicated that the periodicity did not extend over large distances. Both inverse Fourier transform analysis and form factor fitting suggested formation of a multilamellar vesicle. These results were confirmed by cryo-TEM images in which multilamellar complexes with diameters between 50 and 150 nm were observed with no more than seven lamellae per aggregate. In contrast to complexes of reduced BFDMA and DNA, Bragg peaks were absent in SANS spectra of complexes formed by oxidized BFDMA and DNA at all charge ratios investigated. The low-q behavior of the SANS data obtained using oxidized BFDMA and DNA complexes suggested that large, loose aggregates were formed, consistent with complementary cryo-TEM images showing predominantly loose disordered aggregates. Some highly ordered spongelike and cubic phase nanostructures were also detected in cryo-TEM images. We conclude that control of BFDMA oxidation state can be used to manipulate the nanostructures of lipid-DNA complexes formed using BFDMA.

  18. Effect of nature of base cation on surface conductivity of H forms of stratified silicates

    International Nuclear Information System (INIS)

    Vasil'ev, N.G.; Ovcharenko, F.D.; Savkin, A.G.

    1976-01-01

    Interpretation has been proposed for curves of conductometric titration of diluted suspensions of natural silicates in hydrogen forms with solutions of alkalies and organic bases. The curves of conductometric are presented for suspensions of H-form of montmorillonite with solutions of alkali metal hydroxides and with Ba(OH) 2 . A linear decrease in electroconductiv;ty of the system is observed when H-mineral is neutralized with LIOH and NaOH solution. If hydroxides of other metals are added to such a system, the titration curves have an anomalous character. It is especially pronounced when H-mineral is titrated with RbOH and CsOH solutions. When these solutions are added to the suspension of h H-mineral, an additional amount of highly mobile H+-ions is formed which increases electroconductivity of the system. When all the exchange protons in a flat double layer are replaced by Rb 1 or Cs 1 ions, electroconductivity decreases which is related to neutralization of protons in the diffusion part of the layer

  19. A Light-Responsive Self-Assembly Formed by a Cationic Azobenzene Derivative and SDS as a Drug Delivery System.

    Science.gov (United States)

    Geng, Shengyong; Wang, Yuzhu; Wang, Liping; Kouyama, Tsutomu; Gotoh, Toshiaki; Wada, Satoshi; Wang, Jin-Ye

    2017-01-04

    The structure of a self-assembly formed from a cationic azobenzene derivative, 4-cholesterocarbonyl-4'-(N,N,N-triethylamine butyloxyl bromide) azobenzene (CAB) and surfactant sodium dodecyl sulfate (SDS) in aqueous solution was studied by cryo-TEM and synchrotron radiation small-angle X-ray scattering (SAXS). Both unilamellar and multilamellar vesicles could be observed. CAB in vesicles were capable to undergo reversible trans-to-cis isomerization upon UV or visible light irradiation. The structural change upon UV light irradiation could be catched by SAXS, which demonstrated that the interlamellar spacing of the cis-multilamellar vesicles increased by 0.2-0.3 nm. Based on this microstructural change, the release of rhodamine B (RhB) and doxorubicin (DOX) could be triggered by UV irradiation. When incubated NIH 3T3 cells and Bel 7402 cells with DOX-loaded CAB/SDS vesicles, UV irradiation induced DOX release decreased the viability of both cell lines significantly compared with the non-irradiated cells. The in vitro experiment indicated that CAB/SDS vesicles had high efficiency to deliver loaded molecules into cells. The in vivo experiment showed that CAB/SDS vesicles not only have high drug delivery efficiency into rat retinas, but also could maintain high drug concentration for a longer time. CAB/SDS catanionic vesicles may find potential applications as a smart drug delivery system for controlled release by light.

  20. A Light-Responsive Self-Assembly Formed by a Cationic Azobenzene Derivative and SDS as a Drug Delivery System

    Science.gov (United States)

    Geng, Shengyong; Wang, Yuzhu; Wang, Liping; Kouyama, Tsutomu; Gotoh, Toshiaki; Wada, Satoshi; Wang, Jin-Ye

    2017-01-01

    The structure of a self-assembly formed from a cationic azobenzene derivative, 4-cholesterocarbonyl-4‧-(N,N,N-triethylamine butyloxyl bromide) azobenzene (CAB) and surfactant sodium dodecyl sulfate (SDS) in aqueous solution was studied by cryo-TEM and synchrotron radiation small-angle X-ray scattering (SAXS). Both unilamellar and multilamellar vesicles could be observed. CAB in vesicles were capable to undergo reversible trans-to-cis isomerization upon UV or visible light irradiation. The structural change upon UV light irradiation could be catched by SAXS, which demonstrated that the interlamellar spacing of the cis-multilamellar vesicles increased by 0.2-0.3 nm. Based on this microstructural change, the release of rhodamine B (RhB) and doxorubicin (DOX) could be triggered by UV irradiation. When incubated NIH 3T3 cells and Bel 7402 cells with DOX-loaded CAB/SDS vesicles, UV irradiation induced DOX release decreased the viability of both cell lines significantly compared with the non-irradiated cells. The in vitro experiment indicated that CAB/SDS vesicles had high efficiency to deliver loaded molecules into cells. The in vivo experiment showed that CAB/SDS vesicles not only have high drug delivery efficiency into rat retinas, but also could maintain high drug concentration for a longer time. CAB/SDS catanionic vesicles may find potential applications as a smart drug delivery system for controlled release by light.

  1. Changes in the infrared microspectroscopic characteristics of DNA caused by cationic elements, different base richness and single-stranded form.

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    Maria Luiza S Mello

    Full Text Available BACKGROUND: The infrared (IR analysis of dried samples of DNA and DNA-polypeptide complexes is still scarce. Here we have studied the FT-IR profiles of these components to further the understanding of the FT-IR signatures of chromatin and cell nuclei. METHODOLOGY/PRINCIPAL FINDINGS: Calf thymus and salmon testis DNA, and complexes of histone H1, protamine, poly-L-lysine and poly-L-arginine (histone-mimic macromolecules with DNA were analyzed in an IR microspectroscope equipped with an attenuated total reflection diamond objective and Grams software. Conditions including polypeptides bound to the DNA, DNA base composition, and single-stranded form were found to differently affect the vibrational characteristics of the chemical groups (especially, PO(2(- in the nucleic acid. The antisymmetric stretching (ν(as of the DNA PO(2(- was greater than the symmetric stretching (ν(s of these groups and increased in the polypeptide-DNA complexes. A shift of the ν(as of the DNA PO(2(- to a lower frequency and an increased intensity of this vibration were induced especially by lysine-rich histones. Lysine richness additionally contributed to an increase in the vibrational stretching of the amide I group. Even in simple molecules such as inorganic phosphates, the vibrational characteristics of the phosphate anions were differently affected by different cations. As a result of the optimization of the DNA conformation by binding to arginine-rich polypeptides, enhancements of the vibrational characteristics in the FT-IR fingerprint could be detected. Although different profiles were obtained for the DNA with different base compositions, this situation was no longer verified in the polypeptide-DNA complexes and most likely in isolated chromatin or cell nuclei. However, the ν(as PO(2(-/ν(s PO(2(- ratio could discriminate DNA with different base compositions and DNA in a single-stranded form. CONCLUSIONS/SIGNIFICANCE: FT-IR spectral profiles are a valuable tool

  2. Interaction between cationic and conventional nonionic surfactants in the mixed micelle and monolayer formed in aqueous medium

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    Nabel A. Negm

    2011-01-01

    Full Text Available Mixed micellization and surface properties of cationic and nonionic surfactants dimethyl decyl-, tetradecyl- and hexadecyl phosphineoxide mixtures are studied using conductivity and surface tension measurements. The models of Rubingh, Rosen, and Clint, are used to obtain the interaction parameter, minimum area per molecule, mixed micelle composition, free energies of mixing and activity coefficients. The micellar mole fractions were always higher than ideal values indicating high contributions of cationics in mixed micelles. Activity coefficients were less than unity indicating synergism in micelles. The negative free energies of mixing showed the stability of the surfactants in the mixed micelles.

  3. The solid-state structures of organic salts formed by calix[4]arene dihydroxyphosphonic acid with nucleic bases cations: adeninium, cytosinium, guaninium and uracilium

    KAUST Repository

    Shkurenko, Aleksander

    2018-02-19

    Calix[4]arene dihydroxyphosphonic acid has been demonstrated to possess an interesting range of biological properties, including atypical anti-cancer activity. The robustness of calix[4]arene dihydroxyphosphonic acid and its ubiquitous dimeric motif offers perspectives for pre-defined solid state complexation with small molecules. In the current article we describe co-crystals (organic salts) of calix[4]arene dihydroxyphosphonic acid with four nucleic base cations: adeninium, cytosinium, guaninium and uracilium. A number of characteristic interactions between the components in the four co-crystals are pointed out also using the Hirshfeld surface analysis. All the four co-crystals are based on layers of calix[4]arene dimers, alternating with layers of nucleic acid molecules. Two of the reported crystal structures (cytosinium and guaninium) are 1D channel-type structures, while the two others (adeninium and uracilium) represent 2D channel-type structures. In three out of four reported structures, interactions between the cations of nucleic bases are present generating 1D chains of cations. A constant motif is that the nucleic base is present in a type of cavity formed by one aromatic ring and a phosphonic acid moiety.

  4. Study of the formation and solution properties of worm-like micelles formed using both N-hexadecyl-N-methylpiperidinium bromide-based cationic surfactant and anionic surfactant.

    Directory of Open Access Journals (Sweden)

    Zhihu Yan

    Full Text Available The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB with the anionic surfactant sodium laurate (SL in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles.

  5. Short, Synthetic Cationic Peptides Have Antibacterial Activity against Mycobacterium smegmatis by Forming Pores in Membrane and Synergizing with Antibiotics.

    Science.gov (United States)

    Gupta, Kajal; Singh, Sameer; van Hoek, Monique L

    2015-08-24

    Multicellular organisms are constantly exposed to a multitude of pathogenic microbes. Infection is inhibited in vivo by the innate and adaptive immune system. Mycobacterium species have emerged that are resistant to most antibiotics. We identified several naturally occurring cationic antimicrobial peptides that were active at low micromolar concentrations against Mycobacterium smegmatis. Human-derived cathelicidin LL-37 is well characterized and studied against M. smegmatis; we compared LL-37 with Chinese cobra-derived cathelicidin NA-CATH and mouse cathelicidin (mCRAMP). Two synthetic 11-residue peptides (ATRA-1A and ATRA-2) containing variations of a repeated motif within NA-CATH were tested for their activity against M. smegmatis along with a short synthetic peptide derivative from the human beta-defensin hBD3 (hBD3-Pep4). We hypothesized that these smaller synthetic peptides may demonstrate antimicrobial effectiveness with shorter length (and at less cost), making them strong potential candidates for development into broad-spectrum antimicrobial compounds or use in combination with antibiotics. These peptides have antimicrobial activity with EC50 ranging from 0.05 to 1.88 μg/mL against Mycobacterium smegmatis. The ATRA-1A short peptide was found to be the most effective antimicrobial peptide (AMP) (EC50 = 0.05 μg/mL). High bactericidal activity correlated with bacterial membrane depolarization and permeabilization activities. The efficacy of the peptides was further analyzed through Minimal Inhibitory Concentration (MIC) assays. The MICs were determined by the microdilution method. The peptide mCRAMP showed the best MIC activity at 15.6 μg/mL. Neither of the effective short synthetic peptides demonstrated synergy with the antibiotic rifampicin, although both demonstrated synergy with the cyclic peptide antibiotic polymyxin B. The peptides LL-37 and mCRAMP displayed synergism with rifampicin in MIC assays, whereas antibiotic polymyxin B displayed synergism

  6. Short, Synthetic Cationic Peptides Have Antibacterial Activity against Mycobacterium smegmatis by Forming Pores in Membrane and Synergizing with Antibiotics

    Directory of Open Access Journals (Sweden)

    Kajal Gupta

    2015-08-01

    Full Text Available Multicellular organisms are constantly exposed to a multitude of pathogenic microbes. Infection is inhibited in vivo by the innate and adaptive immune system. Mycobacterium species have emerged that are resistant to most antibiotics. We identified several naturally occurring cationic antimicrobial peptides that were active at low micromolar concentrations against Mycobacterium smegmatis. Human-derived cathelicidin LL-37 is well characterized and studied against M. smegmatis; we compared LL-37 with Chinese cobra-derived cathelicidin NA-CATH and mouse cathelicidin (mCRAMP. Two synthetic 11-residue peptides (ATRA-1A and ATRA-2 containing variations of a repeated motif within NA-CATH were tested for their activity against M. smegmatis along with a short synthetic peptide derivative from the human beta-defensin hBD3 (hBD3-Pep4. We hypothesized that these smaller synthetic peptides may demonstrate antimicrobial effectiveness with shorter length (and at less cost, making them strong potential candidates for development into broad-spectrum antimicrobial compounds or use in combination with antibiotics. These peptides have antimicrobial activity with EC50 ranging from 0.05 to 1.88 μg/mL against Mycobacterium smegmatis. The ATRA-1A short peptide was found to be the most effective antimicrobial peptide (AMP (EC50 = 0.05 μg/mL. High bactericidal activity correlated with bacterial membrane depolarization and permeabilization activities. The efficacy of the peptides was further analyzed through Minimal Inhibitory Concentration (MIC assays. The MICs were determined by the microdilution method. The peptide mCRAMP showed the best MIC activity at 15.6 μg/mL. Neither of the effective short synthetic peptides demonstrated synergy with the antibiotic rifampicin, although both demonstrated synergy with the cyclic peptide antibiotic polymyxin B. The peptides LL-37 and mCRAMP displayed synergism with rifampicin in MIC assays, whereas antibiotic polymyxin B displayed

  7. GAS PHASE STRUCTURE AND STABILITY OF COMPLEX FORMED BY H2O, NH3, H2S AND THEIR METHYL DERIVATIVES WITH THE CATION CO2+

    Directory of Open Access Journals (Sweden)

    Cahyorini Kusumawardani

    2010-06-01

    Full Text Available Ab initio molecular orbital calculations at the Hartree-Fock-Self Consistent Field (HF-SCF have been performed in order to determine the structure and gas phase energies of complex formed by the Lewis bases of H2O, NH3, H2S and their methyl derivatives with the cation Co2+. The relative basicities of the base studied depend on both the substituent. The gas-phase interaction energies computed by the SCF method including electron correlation Møller-Plesset 2 (MP2 dan Configuration Iteration (CI were comparable in accuracy. The binding energies computed by these two methods reach the targeted chemical accuracy.   Keywords: ab initio calculation, cobalt complex, structure stability

  8. Small-Angle Neutron Scattering Studies on the Multilamellae Formed by Mixing Lamella-Forming Cationic Diblock Copolymers with Lipids and Their Interaction with DNA.

    Science.gov (United States)

    Yang, Po-Wei; Lin, Tsang-Lang; Liu, I-Ting; Hu, Yuan; Jeng, U-Ser; Gilbert, Elliot Paul

    2016-02-23

    We demonstrate that the lamella-forming polystyrene-block-poly(N-methyl-4-vinylpyridinium iodine) (PS-b-P4VPQ), with similar sizes of the PS and P4VPQ blocks, can be dispersed in the aqueous solutions by forming lipid/PS-b-P4VPQ multilamellae. Using small-angle neutron scattering (SANS) and 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (d62-DPPC) in D2O, a broad correlation peak is found in the scattering profile that signifies the formation of the loosely ordered d62-DPPC/PS-b-P4VPQ multilamellae. The thicknesses of the hydrophobic and hydrophilic layers of the d62-DPPC/PS-b-P4VPQ multilamellae are close to the PS layer and the condensed brush layer thicknesses as determined from previous neutron reflectometry studies on the PS-b-P4VPQ monolayer at the air-water interface. Such well-dispersed d62-DPPC/PS-b-P4VPQ multilamellae are capable of forming multilamellae with DNA in aqueous solution. It is found that the encapsulation of DNA in the hydrophilic layer of the d62-DPPC/PS-b-P4VPQ multilamellae slightly increases the thickness of the hydrophilic layer. Adding CaCl2 can enhance the DNA adsorption in the hydrophilic brush layer, and it is similar to that observed in the neutron reflectometry study of the DNA adsorption by the PS-b-P4VPQ monolayer.

  9. Observation of covalent and electrostatic bonds in nitrogen-containing polycyclic ions formed by gas phase reactions of the benzene radical cation with pyrimidine.

    Science.gov (United States)

    Attah, Isaac Kwame; Soliman, Abdel-Rahman; Platt, Sean P; Meot-Ner Mautner, Michael; Aziz, Saaudallah G; Samy El-Shall, M

    2017-03-01

    Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic nitrogen heterocyclics (PANHs) are present in ionizing environments, including interstellar clouds and solar nebulae, where their ions can interact with neutral PAH and PANH molecules leading to the formation of a variety of complex organics including large N-containing ions. Herein, we report on the formation of a covalently-bonded (benzene·pyrimidine) radical cation dimer by the gas phase reaction of pyrimidine with the benzene radical cation at room temperature using the mass-selected ion mobility technique. No ligand exchange reactions with benzene and pyrimidine are observed indicating that the binding energy of the (benzene·pyrimidine)˙ + adduct is significantly higher than both the benzene dimer cation and the proton-bound pyrimidine dimer. The (benzene·pyrimidine)˙ + adduct shows thermal stability up to 541 K. Thermal dissociation of the (C 6 D 6 ·C 4 H 4 N 2 )˙ + adduct at temperatures higher than 500 K produces C 4 H 4 N 2 D + (m/z 82) suggesting the transfer of a D atom from the C 6 D 6 moiety to the C 4 H 4 N 2 moiety before the dissociation of the adduct. Mass-selected ion mobility of the (benzene·pyrimidine)˙ + dimer reveals the presence of two families of isomers formed by electron impact ionization of the neutral (benzene·pyrimidine) dimer. The slower mobility peak corresponds to a non-covalent family of isomers with larger collision cross sections (76.0 ± 1.8 Å 2 ) and the faster peak is consistent with a family of covalent isomers with more compact structures and smaller collision cross sections (67.7 ± 2.2 Å 2 ). The mobility measurements at 509 K show only one peak corresponding to the family of stable covalently bonded isomers characterized by smaller collision cross sections (66.9 ± 1.9 Å 2 at 509 K). DFT calculations at the M06-2X/6-311++G** level show that the most stable (benzene·pyrimidine)˙ + isomer forms a covalent C-N bond with a binding energy of 49

  10. Selective entrapment of the cationic form of norfloxacin within anionic sodium dodecyl sulfate micelles at physiological pH and its effect on the drug photodecomposition.

    Science.gov (United States)

    Sortino, Salvatore

    2006-01-01

    The binding of the photosensitizing fluoroquinolone (FQ) antibiotic norfloxacin (NX) to sodium dodecyl sulfate (SDS) micelles and the photoreactivity of the NX/SDS complex under physiological pH conditions are investigated by means of absorption and emission spectroscopy, steady-state and laser flash photolysis. It is shown that the photolabile zwitterionic form of NX, which is dominant at physiological pH, is not the most abundant species in the presence of SDS micelles. This medium exhibits a high preference for the cationic form of the drug, which is selectively and successfully entrapped within the micellar cage (K(ass) = 6 x 10(4) M(-1) +/- 3000), becoming the largely dominant species at neutral pH. The effect of this trapping is drastically reflected on both efficiency and nature of the drug photodecomposition. It is observed that the photostability of NX incorporated in the micellar pseudophase increases of more than one order of magnitude if compared to that of the "free" drug. Furthermore, the radical photodecomposition mechanism occurring in phosphate buffered solution is suppressed by the micellar medium and the low photodegradation observed seems to take place preferentially through an ionic pathway. Hopefully, the results presented herein may contribute to a better understanding of the bio-distribution of NX in biological systems and provide helpful and stimulating information in order to get the control of FQ photoreactivity under physiological pH conditions.

  11. An electronic spectroscopic study of micellisation of surfactants and solvation of homomicelles formed by cationic or anionic surfactants using a solvatochromic electron donor acceptor dye.

    Science.gov (United States)

    Kedia, Niraja; Sarkar, Amrita; Purkayastha, Pradipta; Bagchi, Sanjib

    2014-10-15

    Solvatochromic absorption and fluorescence bands of a donor-acceptor dye have been utilised for following the micellisation and for probing the polarity of the aqueous homomicellar phase provided separately by cationic (cetyltrimethylammonimum bromide, CTAB and dodecyltrimethylammonimum bromide, DTAB) and anionic (sodium dodecyl sulphate, SDS) surfactant. Results indicate that for a low concentration of surfactant (below cmc) the dye forms a dimer in aqueous solution. In a micellar media, however, the dye exists as monomers. A strong dye-micelle interaction, as indicated by the shift of the solvatochromic intramolecular charge transfer band of the dye, has also been indicated. The absorption and fluorescence parameters of the dye have been utilised for studying the onset of aggregation of the surfactants. An iterative procedure has been developed for the estimation of cmc and the distribution coefficient (KD) of the dye between the aqueous and the micellar phase. All the parameters provide convergent values of cmc. A high value of KD indicates that the dye exists predominantly in the micellar phase. The solvatochromic parameters characterising the dipolarity-polarisability (π(*)) and H-bond donation ability (α) of modes of solvation interaction in different micellar media have been estimated. The dye is found to distribute itself between two regions in a catanionic vesicle formed by surfactants SDS and DTAB, one being relatively polar than other. The distribution coefficients have been found out using the fluorescence data. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Quantitative analysis of free and bonded forms of volatile sulfur compouds in wine. Basic methodologies and evidences showing the existence of reversible cation-complexed forms.

    Science.gov (United States)

    Franco-Luesma, Ernesto; Ferreira, Vicente

    2014-09-12

    This paper examines first some basic aspects critical to the analysis of Volatile Sulfur Compounds (VSCs), such as the analytical characteristics of the GC-pFPD system and the stability of the different standard solutions required for a proper calibration. Following, a direct static headspace analytical method for the determination of exclusively free forms of VSCs has been developed. Method repeatability is better than 4%, detection limits for main analytes are below 0.5μgL(-1), and the method dynamic linear range (r(2)>0.99) is expanded by controlling the split ratio in the chromatographic inlet to cover the natural range of occurrence of these compounds in wines. The method gives reliable estimates of headspace concentrations but, as expected, suffers from strong matrix effects with recoveries ranging from 0 to 100% or from 60 to 100 in the cases of H2S and the other mercaptans, respectively. This demonstrates the existence of strong interactions of these compounds with different matrix components. The complexing ability of Cu(2+) and to a lower extent Fe(2+) and Zn(2+) has been experimentally checked. A previously developed method in which the wine is strongly diluted with brine and the volatiles are preconcentrated by HS-SPME, was found to give a reliable estimation of the total amount (free+complexed) of mercaptans, demonstrating that metal-mercaptan complexes are reversible. The comparative analysis of different wines by the two procedures reveals that in normal wines H2S and methanethiol can be complexed at levels above 99%, with averages around 97% for H2S and 75% for methanethiol, while thioethers such as dimethyl sulfide (DMS) are not complexed. Overall, the proposed strategy may be generalized to understand problems caused by VSCs in different matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Gas-Phase Intercluster Thiyl-Radical Induced C-H Bond Homolysis Selectively Forms Sugar C2-Radical Cations of Methyl D-Glucopyranoside: Isotopic Labeling Studies and Cleavage Reactions

    Science.gov (United States)

    Osburn, Sandra; Speciale, Gaetano; Williams, Spencer J.; O'Hair, Richard A. J.

    2017-07-01

    A suite of isotopologues of methyl D-glucopyranosides is used in conjunction with multistage mass spectrometry experiments to determine the radical site and cleavage reactions of sugar radical cations formed via a recently developed `bio-inspired' method. In the first stage of CID (MS2), collision-induced dissociation (CID) of a protonated noncovalent complex between the sugar and S-nitrosocysteamine, [H3NCH2CH2SNO + M]+, unleashes a thiyl radical via bond homolysis to give the noncovalent radical cation, [H3NCH2CH2S• + M]+. CID (MS3) of this radical cation complex results in dissociation of the noncovalent complex to generate the sugar radical cation. Replacement of all exchangeable OH and NH protons with deuterons reveals that the sugar radical cation is formed in a process involving abstraction of a hydrogen atom from a C-H bond of the sugar coupled with proton transfer to the sugar, to form [M - H• + D+]. Investigation of this process using individual C-D labeled sugars reveals that the main site of H/D abstraction is the C2 position, since only the C2-deuterium labeled sugar yields a dominant [M - D• + H+] product ion. The fragmentation reactions of the distonic sugar radical cation, [M - H•+ H+], were studied by another stage of CID (MS4). 13C-labeling studies revealed that a series of three related fragment ions each contain the C1-C3 atoms; these arise from cross-ring cleavage reactions of the sugar.

  14. Radical cations in condensed phases

    Energy Technology Data Exchange (ETDEWEB)

    Symons, M.C.R. (Leicester Univ. (UK). Dept. of Chemistry)

    The subject is covered in sections, entitled: introduction (scope of present Review); preparative procedures; alkane and cycloalkane cations; alkene and cyclic alkene cations; alkyl-halide cations; alcohol and ether cations; carbonyl cations (aldehyde, ketone and ester cations); sulphur-centred cations; selenium-centred cations; nitrogen-centred cations; phosphorus-centred cations; tin- and lead-centred cations; aromatic cations; five membered hetero-aromatic cations; vinyl cations; inorganic cations.

  15. Comparative Study Of Two Non-Selective Cyclooxygenase ...

    African Journals Online (AJOL)

    The comparative study of the effects of two non-selective cyclooxygenase inhibitors ibuprofen and paracetamol on maternal and neonatal growth was conducted using 15 Sprague dawley rats, with mean body weight ranging between 165 and 179g. The rats were separated at random into three groups (A, B and C).

  16. Intervention effects of five cations and their correction on hemolytic activity of tentacle extract from the jellyfish Cyanea capillata

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2017-05-01

    Full Text Available Cations have generally been reported to prevent jellyfish venom-induced hemolysis through multiple mechanisms by spectrophotometry. Little attention has been paid to the potential interaction between cations and hemoglobin, potentially influencing the antagonistic effect of cations. Here, we explored the effects of five reported cations, La3+, Mn2+, Zn2+, Cu2+ and Fe2+, on a hemolytic test system and the absorbance of hemoglobin, which was further used to measure their effects on the hemolysis of tentacle extract (TE from the jellyfish Cyanea capillata. All the cations displayed significant dose-dependent inhibitory effects on TE-induced hemolysis with various dissociation equilibrium constant (Kd values as follows: La3+ 1.5 mM, Mn2+ 93.2 mM, Zn2+ 38.6 mM, Cu2+ 71.9 μM and Fe2+ 32.8 mM. The transparent non-selective pore blocker La3+ did not affect the absorbance of hemoglobin, while Mn2+ reduced it slightly. Other cations, including Zn2+, Cu2+ and Fe2+, greatly decreased the absorbance with Kd values of 35.9, 77.5 and 17.6 mM, respectively. After correction, the inhibitory Kd values were 1.4 mM, 45.8 mM, 128.5 μM and 53.1 mM for La3+, Zn2+, Cu2+ and Fe2+, respectively. Mn2+ did not inhibit TE-induced hemolysis. Moreover, the inhibitory extent at the maximal given dose of all cations except La3+ was also diminished. These corrected results from spectrophotometry were further confirmed by direct erythrocyte counting under microscopy. Our results indicate that the cations, except for La3+, can interfere with the absorbance of hemoglobin, which should be corrected when their inhibitory effects on hemolysis by jellyfish venoms are examined. The variation in the inhibitory effects of cations suggests that the hemolysis by jellyfish venom is mainly attributed to the formation of non-selective cation pore complexes over other potential mechanisms, such as phospholipases A2 (PLA2, polypeptides, protease and oxidation. Blocking the pore-forming

  17. Intervention effects of five cations and their correction on hemolytic activity of tentacle extract from the jellyfishCyanea capillata.

    Science.gov (United States)

    Zhang, Hui; Wang, Qianqian; Xiao, Liang; Zhang, Liming

    2017-01-01

    Cations have generally been reported to prevent jellyfish venom-induced hemolysis through multiple mechanisms by spectrophotometry. Little attention has been paid to the potential interaction between cations and hemoglobin, potentially influencing the antagonistic effect of cations. Here, we explored the effects of five reported cations, La 3+ , Mn 2+ , Zn 2+ , Cu 2+ and Fe 2+ , on a hemolytic test system and the absorbance of hemoglobin, which was further used to measure their effects on the hemolysis of tentacle extract (TE) from the jellyfish Cyanea capillata . All the cations displayed significant dose-dependent inhibitory effects on TE-induced hemolysis with various dissociation equilibrium constant ( K d ) values as follows: La 3+ 1.5 mM, Mn 2+ 93.2 mM, Zn 2+ 38.6 mM, Cu 2+ 71.9 μM and Fe 2+ 32.8 mM. The transparent non-selective pore blocker La 3+ did not affect the absorbance of hemoglobin, while Mn 2+ reduced it slightly. Other cations, including Zn 2+ , Cu 2+ and Fe 2+ , greatly decreased the absorbance with K d values of 35.9, 77.5 and 17.6 mM, respectively. After correction, the inhibitory K d values were 1.4 mM, 45.8 mM, 128.5 μM and 53.1 mM for La 3+ , Zn 2+ , Cu 2+ and Fe 2+ , respectively. Mn 2+ did not inhibit TE-induced hemolysis. Moreover, the inhibitory extent at the maximal given dose of all cations except La 3+ was also diminished. These corrected results from spectrophotometry were further confirmed by direct erythrocyte counting under microscopy. Our results indicate that the cations, except for La 3+ , can interfere with the absorbance of hemoglobin, which should be corrected when their inhibitory effects on hemolysis by jellyfish venoms are examined. The variation in the inhibitory effects of cations suggests that the hemolysis by jellyfish venom is mainly attributed to the formation of non-selective cation pore complexes over other potential mechanisms, such as phospholipases A2 (PLA2), polypeptides, protease and oxidation. Blocking the

  18. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  19. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  20. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomerization of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two sites.

  1. The comparison of the structures of some cationic forms of clinoptilolite obtained from Manisa-Gordes in Turkey using their XRD spectrums

    International Nuclear Information System (INIS)

    Izci, E.; Orhun, O.

    2000-01-01

    In this study, at room temperature, XRD spectrums of Na, Ca, Li, Pb and natural forms of clinoptilolite, which is a natural zeolite obtained from Manisa-Gordes in Turkey, were taken and compared with each other according to their structures. Firstly, clinoptilolite samples, whose, diameters are smaller than 63 μm, were purified by HCl. Thus, impurities through the channels of clinoptilolite samples, were removed from their structures. Then, the samples washed several times by deionised water and filtered. So, HCl was removed from structures of these samples. Na, Ca, Li, Pb ionic forms of clinoptilolite were prepared by using batch method. XRD apparatus from Rigaku-Rint 2000 series. Comparing of XRD spectrums of these ionic and natural forms of clinoptilolite and finding the variations of their spectrums, what changes in their structures could be, were investigated. (authors)

  2. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  3. A small-angle X-ray scattering study of complexes formed in mixtures of a cationic polyelectrolyte and an anionic surfactant

    DEFF Research Database (Denmark)

    Bergström, M.; Kjellin, U.R.M.; Claesson, P.M.

    2002-01-01

    The internal structure of the solid phase formed in mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and a range of oppositely charged polyelectrolytes with different side chains and charge density has been investigated using small-angle X-ray scattering. Polyelectrolytes with short....... The hexagonal structure of MAPTAC is retained either when a neutral monomer (acrylamide, AM) is included in the polymer backbone to reduce the charge density or when a nonionic surfactant is admixed to the SDS/polyelctrolyte complex.. The unit cell length of AM-MAPTAC increases with decreasing charge density...... structure and the bilayers in the lamellar structure are based on self-assembled surfactant aggregates with the polyelectrolyte mainly located in the aqueous region adjacent to the charged surfactant headgroups....

  4. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  5. Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Högström, Jonas, E-mail: jhogstrom@gmail.com; Fredriksson, Wendy, E-mail: wendy.fredriksson@kemi.uu.se; Edstrom, Kristina, E-mail: kristina.edstrom@kemi.uu.se; Björefors, Fredrik, E-mail: fredrik.bjorefors@kemi.uu.se; Nyholm, Leif, E-mail: leif.nyholm@kemi.uu.se; Olsson, Claes-Olof A., E-mail: drclabbe@kth.se

    2013-11-01

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainless steel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method, which is based on analyses of the oxidised metal peaks, provides increased precision and hence allows faster ARXPS measurements to be carried out. The method was used to determine the concentration depth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steel samples oxidised in 0.5 M H{sub 2}SO{sub 4} and acetic acid diluted with 0.02 M Na{sub 2}B{sub 4}O{sub 7} · 10H{sub 2}O and 1 M H{sub 2}O, respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface and the films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer. Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes, the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution. The differences in the layer composition, found for the two electrolytes as well as different oxidation conditions, can be explained based on the oxidation potentials of the metals and the dissolution rates of the different metal ions.

  6. Transient receptor potential (TRP gene superfamily encoding cation channels

    Directory of Open Access Journals (Sweden)

    Pan Zan

    2011-01-01

    Full Text Available Abstract Transient receptor potential (TRP non-selective cation channels constitute a superfamily, which contains 28 different genes. In mammals, this superfamily is divided into six subfamilies based on differences in amino acid sequence homology between the different gene products. Proteins within a subfamily aggregate to form heteromeric or homomeric tetrameric configurations. These different groupings have very variable permeability ratios for calcium versus sodium ions. TRP expression is widely distributed in neuronal tissues, as well as a host of other tissues, including epithelial and endothelial cells. They are activated by environmental stresses that include tissue injury, changes in temperature, pH and osmolarity, as well as volatile chemicals, cytokines and plant compounds. Their activation induces, via intracellular calcium signalling, a host of responses, including stimulation of cell proliferation, migration, regulatory volume behaviour and the release of a host of cytokines. Their activation is greatly potentiated by phospholipase C (PLC activation mediated by coupled GTP-binding proteins and tyrosine receptors. In addition to their importance in maintaining tissue homeostasis, some of these responses may involve various underlying diseases. Given the wealth of literature describing the multiple roles of TRP in physiology in a very wide range of different mammalian tissues, this review limits itself to the literature describing the multiple roles of TRP channels in different ocular tissues. Accordingly, their importance to the corneal, trabecular meshwork, lens, ciliary muscle, retinal, microglial and retinal pigment epithelial physiology and pathology is reviewed.

  7. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomeri- zation of the linear propargyl cation to ..... C3, C4 and C5. The ZPE corrections in each case are derived from the. B3LYP calculations. ..... the converse of which gives the relative capacity of the. LPD's to stabilize TS6 with respect ...

  8. The cation-deficient Ruddlesden-Popper oxysulfide Y2Ti2O5S2 as a layered sulfide: topotactic potassium intercalation to form KY2Ti2O5S2.

    Science.gov (United States)

    Rutt, Oliver J; Hill, Timothy L; Gál, Zoltán A; Hayward, Michael A; Clarke, Simon J

    2003-12-01

    Potassium intercalation into the cation-deficient n = 2 Ruddlesden-Popper oxysulfide Y(2)Ti(2)O(5)S(2) to form KY(2)Ti(2)O(5)S(2) has been carried out by reaction of the oxysulfide with potassium vapor in sealed metal tubes at 400 degrees C, potassium naphthalide in THF at 50 degrees C, or potassium in liquid ammonia at temperatures as low as -78 degrees C. Insertion of potassium is topotactic, and although a site 12-coordinate by oxide ions is vacant in the perovskite-type oxide slabs of the structure, potassium is too large to enter this site via the 4-coordinate window, and instead enters the rock-salt-type sulfide layers of the structure which necessitates a 30% increase in the lattice parameter c normal to the layers. In contrast with one of the sodium intercalates of Y(2)Ti(2)O(5)S(2) (beta-NaY(2)Ti(2)O(5)S(2)) in which sodium occupies a tetrahedral site in the sulfide layers, potassium favors an 8-coordinate site which necessitates a relative translation of adjacent oxide slabs. KY(2)Ti(2)O(5)S(2) is tetragonal: P4/mmm, a = 3.71563(4) A, c = 14.8682(2) A (at 298 K), Z = 1. Although the resistivity (3.4(1) x 10(3) Omega cm) is larger than would be expected for a metal, temperature independent paramagnetism dominates the magnetic susceptibility, and the material is electronically very similar to the analogous sodium intercalate beta-NaY(2)Ti(2)O(5)S(2) which features reduced-titanium-containing oxide layers of very similar geometry and electron count.

  9. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  10. Cation-cation interaction in neptunyl(V) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Krot, N.N. [Russian Academy of Sciences, Institute of Physical Chemistry (Russian Federation); Saeki, Masakatsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The original manuscript was prepared by Professor N.N. Krot of Institute of Physical Chemistry, Russian Academy of Sciences, in 1997. Saeki tried to translate that into Japanese and to add some new data since 1997. The contents include the whole picture of cation-cation interactions mainly in 5-valence neptunium compounds. Firstly, characteristic structures of neptunium are summarized of the cation-cation bonding in compounds. Secondly, it is mentioned how the cation-cation bonding affects physical and chemical properties of the compounds. Then, characterization-methods for the cation-cation bonding in the compounds are discussed. Finally, the cation-cation interactions in compounds of other actinide-ions are shortly reviewed. (author)

  11. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

    Science.gov (United States)

    Bythell, Benjamin J.; Abutokaikah, Maha T.; Wagoner, Ashley R.; Guan, Shanshan; Rabus, Jordan M.

    2017-04-01

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the 0,2 A 2 ion from the sodiated forms . Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies.

  12. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir

    2016-03-01

    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  13. New Horizons in Cationic Photopolymerization

    Directory of Open Access Journals (Sweden)

    Marco Sangermano

    2018-01-01

    Full Text Available In this review, we report some recent advances and new horizons in UV-induced cationic photopolymerization. In particular, after a brief introduction on the discovery and affirmation of the cationic photopolymerization process, new efforts in the synthesis of cationic photoinitiators are reported. Subsequently, an interesting and absolutely new application is reported, related to the combination of Radical-Induced Cationic Photopolymerization with Frontal Polymerization, achieving the cross-linking of epoxy composites.

  14. Non-Selective Lexical Access in Late Arabic-English Bilinguals: Evidence from Gating.

    Science.gov (United States)

    Boudelaa, Sami

    2018-02-07

    Previous research suggests that late bilinguals who speak typologically distant languages are the least likely to show evidence of non-selective lexical access processes. This study puts this claim to test by using the gating task to determine whether words beginning with speech sounds that are phonetically similar in Arabic and English (e.g., [b,d,m,n]) give rise to selective or non-selective lexical access processes in late Arabic-English bilinguals. The results show that an acoustic-phonetic input (e.g., [bæ]) that is consistent with words in Arabic (e.g., [bædrun] "moon") and English (e.g., [bæd] "bad") activates lexical representations in both languages of the bilingual. This non-selective activation holds equally well for mixed lists with words from both Arabic and English and blocked lists consisting only of Arabic or English words. These results suggest that non-selective lexical access processes are the default mechanism even in late bilinguals of typologically distant languages.

  15. Differences in game reading between selected and non-selected youth soccer players

    NARCIS (Netherlands)

    Den Hartigh, Ruud J. R.; Van der Steen, Steffie; Hakvoort, Bas; Frencken, Wouter G. P.; Lemmink, Koen A. P. M.

    2018-01-01

    Applying an established theory of cognitive development - Skill Theory - the current study compares the game-reading skills of youth players selected for a soccer school of a professional soccer club (n=49) and their non-selected peers (n=38). Participants described the actions taking place in

  16. Diversity of selective and non-selective fishing gear and their impact ...

    African Journals Online (AJOL)

    This survey was conducted in Al-Kalakla Fishery (KF) and Jabel Awlia Dam Fishery (JADF) in the White Nile River, Khartoum state to identify the selective and non-selective fishing gear. The results showed the selective fishing gear represented by gill-nets and seine nets (beach nets) in both fisheries with clear variation in ...

  17. Energies and physicochemical properties of cation-π interactions in biological structures.

    Science.gov (United States)

    Du, Qi-Shi; Meng, Jian-Zong; Liao, Si-Ming; Huang, Ri-Bo

    2012-04-01

    The cation-π interactions occur frequently within or between proteins due to six (Phe, Tyr, Trp, Arg, Lys, and His) of the twenty natural amino acids potentially interacting with metallic cations via these interactions. In this study, quantum chemical calculations and molecular orbital (MO) theory are used to study the energies and properties of cation-π interactions in biological structures. The cation-π interactions of H⁺ and Li⁺ are similar to hydrogen bonds and lithium bonds, respectively, in which the small, naked cations H⁺ and Li⁺ are buried deep within the π-electron density of aromatic molecules, forming stable cation-π bonds that are much stronger than the cation-π interactions of other alkali metal cations. The cation-π interactions of metallic cations with atomic masses greater than that of Li⁺ arise mainly from the coordinate bond comprising empty valence atomic orbitals (AOs) of metallic cations and π-MOs of aromatic molecules, though electrostatic interactions may also contribute to the cation-π interaction. The binding strength of cation-π interactions is determined by the charge and types of AOs in the metallic cations. Cation-π interaction energies are distance- and orientation-dependent; energies decrease with the distance (r) and the orientation angle (θ). In solution, the cation-π energies decrease with the increase of the dielectric constant (ɛ) of the solvent; however, solvation has less influence on the H⁺-π and H₃O⁺-π interactions than on interactions with other cations. The conclusions from this study provide useful theoretical insights into the nature of cation-π interactions and may contribute to the development of better force field parameters for describing the molecular dynamics of cation-π interactions within and between proteins. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Differences in game reading between selected and non-selected youth soccer players.

    Science.gov (United States)

    Den Hartigh, Ruud J R; Van Der Steen, Steffie; Hakvoort, Bas; Frencken, Wouter G P; Lemmink, Koen A P M

    2018-02-01

    Applying an established theory of cognitive development-Skill Theory-the current study compares the game-reading skills of youth players selected for a soccer school of a professional soccer club (n = 49) and their non-selected peers (n = 38). Participants described the actions taking place in videos of soccer game plays, and their verbalisations were coded using Skill Theory. Compared to the non-selected players, the selected players generally demonstrated higher levels of complexity in their game-reading, and structured the information of game elements-primarily the player, teammate and field-at higher complexity levels. These results demonstrate how Skill Theory can be used to assess, and distinguish game-reading of youth players with different expertise, a skill important for soccer, but also for other sports.

  19. BEHAVIOR OF THE NON-SELECTIVE HERBICIDE GLYPHOSATE IN AGRICULTURAL SOIL

    OpenAIRE

    Abdul Jabbar Al-Rajab; Othman M. Hakami

    2014-01-01

    Glyphosate [N-phosphonomethyl]glycine is a systematic, non-selective, organophosphorus herbicide used worldwide in agriculture and industrial zones. Following its application, residues of glyphosate can threaten soil or aquatic organisms in adjacent water. In this study, we followed the degradation, stabilization, remobilization and leaching of 14C-glyphosate in three agricultural soils in laboratory incubations and in lysimeters under field condition...

  20. Can non-selective beta-blockers prevent hepatocellular carcinoma in patients with cirrhosis?

    DEFF Research Database (Denmark)

    Thiele, Maja; Wiest, Reiner; Gluud, Lise Lotte

    2013-01-01

    carcinoma via a reduction of the inflammatory load from the gut to the liver and inhibition of angiogenesis. Due to their effect on the portal pressure, non-selective beta-blockers are used for prevention of esophageal variceal bleeding. Recently, non-hemodynamic effects of beta-blockers have received......-up. Observational studies carry a high risk of bias. The meta-analytic approach may be used if the incidence and mortality of hepatocellular carcinoma can be extracted from trials on variceal bleeding and if the combined sample size and follow up is sufficient....

  1. Non-selective beta-blockers may reduce risk of hepatocellular carcinoma

    DEFF Research Database (Denmark)

    Thiele, Maja; Albillos, Agustín; Abazi, Rozeta

    2015-01-01

    BACKGROUND & AIMS: Non-selective beta-blockers (NSBB) are used in patients with cirrhosis and oesophageal varices. Experimental data suggest that NSBB inhibit angiogenesis and reduce bacterial translocation, which may prevent hepatocellular carcinoma (HCC). We therefore assessed the effect of NSBB.......052 to -0.001; number needed to treat 38 patients). There was no heterogeneity (I(2) = 7%) or evidence of small study effects (Eggers P = 0.402). The result was not confirmed in sequential analysis, which suggested that 3719 patients were needed to achieve the required information size. NSBB did not reduce...

  2. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  3. Multivariate Profiles of Selected Versus non-Selected Elite Youth Brazilian Soccer Players

    Directory of Open Access Journals (Sweden)

    Aquino Rodrigo

    2017-12-01

    Full Text Available This study determined whether a multivariate profile more effectively discriminated selected than non-selected elite youth Brazilian soccer players. This examination was carried out on 66 youth soccer players (selected, n = 28, mean age 16.3 ± 0.1; non-selected, n = 38, mean age 16.7 ± 0.4 using objective instruments. Multivariate profiles were assessed through anthropometric characteristics, biological maturation, tactical-technical skills, and motor performance. The Student’s t-test identified that selected players exhibited significantly higher values for height (t = 2.331, p = 0.02, lean body mass (t = 2.441, p = 0.01, and maturity offset (t = 4.559, p < 0.001, as well as performed better in declarative tactical knowledge (t = 10.484, p < 0.001, shooting (t = 2.188, p = 0.03, dribbling (t = 5.914, p < 0.001, speed – 30 m (t = 8.304, p < 0.001, countermovement jump (t = 2.718, p = 0.008, and peak power tests (t = 2.454, p = 0.01. Forward stepwise discriminant function analysis showed that declarative tactical knowledge, running speed –30 m, maturity offset, dribbling, height, and peak power correctly classified 97% of the selected players. These findings may have implications for a highly efficient selection process with objective measures of youth players in soccer clubs.

  4. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  5. Fetal biometric parameters: Reference charts for a non-selected risk population from Uberaba, Brazil

    Directory of Open Access Journals (Sweden)

    Alberto Borges Peixoto

    2017-03-01

    Full Text Available Objective: To establish reference charts for fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil. Methods: A retrospective cross-sectional study was performed among 5656 non-selected risk singleton pregnant women between 14 and 41 weeks of gestation. The ultrasound exams were performed during routine visits of second and third trimesters. Biparietal diameter (BPD was measured at the level of the thalami and cavum septi pellucidi. Head circumference (HC was calculated by the following formula: HC = 1.62*(BPD + occipital frontal diameter, OFD. Abdominal circumference (AC was measured using the following formula: AC = (anteroposterior diameter + transverse abdominal diameter × 1.57. Femur diaphysis length (FDL was obtained in the longest axis of femur without including the distal femoral epiphysis. The estimated fetal weight (EFW was obtained by the Hadlock formula. Polynomial regressions were performed to obtain the best-fit model for each fetal biometric parameter as the function of gestational age (GA. Results: The mean, standard deviations (SD, minimum and maximum of BPD (cm, HC (cm, AC (cm, FDL (cm and EFW (g were 6.9 ± 1.9 (2.3 – 10.5, 24.51 ± 6.61 (9.1 – 36.4, 22.8 ± 7.3 (7.5 – 41.1, 4.9 ± 1.6 (1.2 – 8.1 and 1365 ± 1019 (103 – 4777, respectively. Second-degree polynomial regressions between the evaluated parameters and GA resulted in the following formulas: BPD = –4.044 + 0.540 × GA – 0.0049 × GA² (R² = 0.97; HC= –15.420 + 2.024 GA – 0.0199 × GA² (R² = 0.98; AC = –9.579 + 1.329 × GA – 0.0055 × GA² (R² = 0.97; FDL = –3.778 + 0.416 × GA – 0.0035 × GA² (R² = 0.98 and EFW = 916 – 123 × GA + 4.70 × GA² (R² = 0.96; respectively. Conclusion: Reference charts for the fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil, were established.

  6. Converting Hg-1212 to Tl-2212 via Tl-Hg cation exchange in combination with Tl cation intercalation

    International Nuclear Information System (INIS)

    Zhao Hua; Wu, Judy Z

    2007-01-01

    In a cation exchange process developed recently for epitaxy of HgBa 2 CaCu 2 O 6 (Hg-1212) thin films, TlBa 2 CaCu 2 O 7 (Tl-1212) or Tl 2 Ba 2 CaCu 2 O 9 (Tl-2212) precursor films were employed as the precursor matrices and Hg-1212 was obtained by replacing Tl cations on the precursor lattice with Hg cations. The reversibility of the cation exchange dictates directly the underlying mechanism. Following our recent success in demonstrating a complete reversibility within '1212' structure, we show the conversion from Hg-1212 to Tl-2212 can be achieved via two steps: conversion from Hg-1212 to Tl-1212 followed by Tl intercalation to form double Tl-O plans in each unit cell. The demonstrated reversibility of the cation exchange process has confirmed the process is a thermal perturbation of weakly bonded cations on the lattice and the direction of the process is determined by the population ratio between the replacing cations and that to be replaced

  7. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... and KCN, are selectively bound to the catalyst, providing exceptionally high enantioselectivities for kinetic resolutions, elimination reactions (fluoride base), and Strecker synthesis (cyanide nucleophile). Asymmetric cation-binding catalysis was recently expanded to silicon-based reagents, enabling...

  8. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  9. Unusual 4-arsonoanilinium cationic species in the hydrochloride salt of (4-aminophenyl)arsonic acid and formed in the reaction of the acid with copper(II) sulfate, copper(II) chloride and cadmium chloride.

    Science.gov (United States)

    Smith, Graham; Wermuth, Urs D

    2017-04-01

    Structures having the unusual protonated 4-arsonoanilinium species, namely in the hydrochloride salt, C 6 H 9 AsNO 3 + ·Cl - , (I), and the complex salts formed from the reaction of (4-aminophenyl)arsonic acid (p-arsanilic acid) with copper(II) sulfate, i.e. hexaaquacopper(II) bis(4-arsonoanilinium) disulfate dihydrate, (C 6 H 9 AsNO 3 ) 2 [Cu(H 2 O) 6 ](SO 4 ) 2 ·2H 2 O, (II), with copper(II) chloride, i.e. poly[bis(4-arsonoanilinium) [tetra-μ-chlorido-cuprate(II)

  10. [Effects of copper and zinc cations bound by gamma-globulin fraction in Staphylococcus aureus culture].

    Science.gov (United States)

    Cheknev, S B; Vostrova, E I; Piskovskaia, L S; Vostrov, A V

    2014-01-01

    AIM. Evaluation of Staphylococcus aureus culture growth dynamics in the presence of gamma-globulin: metal-complexes formed with copper and zinc cations as well as cations of metals used in isolation during the first 24 hours of exposition. . Samples of human gamma-globulin metal-complexes with copper or zinc cations at a final concentration of 0.5 microg/ml were introduced into S. aureus bacteria suspensions containing approximately 10(3) CFU/ml. Suspension at the volume of 5.0 ml was incubated at 37 degrees C for 24 hours with sampling and CFU calculation in the culture at various exposure periods. An accepted micromethod for determination of viability of bacteria was used. The protein transformed by copper cation binding realizes bacteriostatic activity in the logarithmic growth phase of S. aureus culture from 3.0 to 6.0 hours of incubation. Free copper cations inhibit bacterial reproduction at a higher degree than the metal-complex. The protein transformed by zinc cation binding realizes bacteriostatic activity at 1.5 hours of S. aureus incubation. Free zinc cations do not have bacteriostatic effect against S. aureus. Proteins of the gamma-globulin fraction in the range of physiological concentrations forming metal-complexes with copper and zinc cations may be factors that have cytostatic effect against S. aureus bacteria. Zinc cations realize bacteriostatic activity only in gamma-gloulin bound state whereas copper cations--also in the free state.

  11. Laser surface treatment on a nickel based alloy in order to form chromium oxide to reduce cations release in primary circuit. Experimental and numerical study of laser mater interaction

    International Nuclear Information System (INIS)

    Gouton, Lucille

    2015-01-01

    Alloy 690 (60%Ni, 30%Cr, 10%Fe) is mainly used in primary circuit pipes for nuclear power plants.The aim of this thesis is to form a Cr 2 O 3 layer, using laser surface melting, with the objective of creating a chromium-rich oxide layer. In order to optimize the treatment, it was first important to determine parameters influence on the layer oxide properties then, with the objective of a deeper understanding of mechanisms involved, to address thermo-physical phenomena occurring during and after the laser pulse striking the upper surface. A deep parametric study first enabled to find an optimized laser surface treatment which produces chromium enrichment of the upper surface and a dense and continuous oxide layer. This treatment has been applied on samples, set in a primary medium simulation loop. Experiments and calculations were carried out to provide understanding of surface chromium enrichment by laser process. The results were shown to explain chromium enrichment until melt pool solidification occurred on the upper surface, assumingly just before chromium oxide formation. This was also promoted by a high affinity with oxygen and a higher stability of Cr 2 O 3 oxide compared with other potential oxide formation. (author) [fr

  12. [Antioxidant activity of cationic whey protein isolate].

    Science.gov (United States)

    titova, M E; Komolov, S A; Tikhomirova, N A

    2012-01-01

    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pisolate has an antioxidant

  13. Economic evaluation of etoricoxib versus non-selective NSAIDs in the treatment of ankylosing spondylitis in the UK.

    Science.gov (United States)

    Jansen, Jeroen P; Pellissier, James; Choy, Ernest H; Ostor, Andrew; Nash, Julian T; Bacon, Paul; Hunsche, Elke

    2007-12-01

    To evaluate the cost-effectiveness of etoricoxib, a cyclooxygenase (COX)-2 selective inhibitor, versus non-selective nonsteroidal anti-inflammatory drugs (nsNSAIDs) in the treatment of ankylosing spondylitis (AS). The cost-effectiveness of etoricoxib versus nsNSAIDs was evaluated from the UK National Health Service (NHS) and society perspective with a decision-analytic model. Patients stayed on initial therapy throughout 52 weeks unless they experienced an adverse event (AE) or lacked efficacy, in which case they switched to another nsNSAID or a tumor necrosis factor alpha antagonist. Efficacy data were obtained from a 1-year etoricoxib clinical trial in AS. Bath AS Functional Index (BASFI) data were translated into Quality Adjusted Life Year (QALY) weights using a published data on the relation between BASFI and Short-form (SF) 36 Quality of life scores, as well as the relation between SF-36 and utility. Safety data were based on meta-analyses of etoricoxib trials. Information on treatment pathways, resource consumption, and absenteeism from work was obtained from literature and experts. Model outcomes included QALYs, perforations, ulcers, or bleeds, cardiovascular events, and costs. Etoricoxib was cost-effective compared to nsNSAIDs in terms of cost per QALY saved ( pound5611). Probabilistic sensitivity analysis found a 77% probability of the incremental cost per QALY saved being within a threshold for cost-effectiveness of pound20 000. The expected direct costs over the 52-week period were pound1.23 (95% uncertainty distribution pound1.10; pound1.39) and pound1.13 per day ( pound0.78; pound1.55) for patients starting with etoricoxib and nsNSAIDs, respectively. When costs related to absenteeism were taken into account, the cost per QALY saved was pound281. Given the underlying assumptions and data used, this economic evaluation demonstrated that, compared to nsNSAIDs, etoricoxib is a cost-effective therapy for AS patients in the UK.

  14. Evaluation of non-selective refocusing pulses for 7 T MRI

    Science.gov (United States)

    Moore, Jay; Jankiewicz, Marcin; Anderson, Adam W.; Gore, John C.

    2012-01-01

    There is a continuing need for improved RF pulses that achieve proper refocusing in the context of ultra-high field (⩾7 T) human MRI. Simple block or sinc pulses are highly susceptible to RF field inhomogeneities, and adiabatic pulses are generally considered too SAR intensive for practical use at 7 T. The performance of the array of pulses falling between these extremes, however, has not been systematically evaluated. The aim of this work was to compare the performances of 21 non-selective refocusing pulses spanning a range of durations and SAR levels. The evaluation was based upon simulations and both phantom and in vivo human brain experiments conducted at 7 T. Tested refocusing designs included block, composite block, BIR-4, hyperbolic secant, and numerically optimized composite waveforms. These pulses were divided into three SAR classes and two duration categories, and, based on signal gain in a 3-D spin echo sequence, practical recommendations on usage are made within each category. All evaluated pulses were found to produce greater volume-averaged signals relative to a 180° block pulse. Although signal gains often come with the price of increased SAR or duration, some pulses were found to result in significant signal enhancement while also adhering to practical constraints. This work demonstrates the signal gains and losses realizable with single-channel refocusing pulse designs and should assist in the selection of suitable refocusing pulses for practical 3-D spin-echo imaging at 7 T. It further establishes a reference against which future pulses and multi-channel designs can be compared.

  15. Interactions of nucleobases with alkali earth metal cations--electrospray ionization mass spectrometric study.

    Science.gov (United States)

    Frańska, Magdalena

    2007-01-01

    Interactions of nucleobases with alkali earth metal cations have been studied by electrospray ionization mass spectrometry (ESI-MS). Nucleobases containing at least one oxygen atom form stable complexes with alkali earth metal cations. This phenomenon can be explained on the grounds of the well known theory of hard and soft acids and bases. Uracil and thymine make complexes only when in their deprotonoted forms. The cations of great radii (Sr(2+), Ba(2+)) are more prone to form complexes of stoichiometry 1:1 with uracil and thymine than the cations of small radii (Mg(2+), Ca(2+)). On the other hand, Mg(2+) forms complexes of stoichiometry 2:1 and 3:2 with uracil and thymine. Gas-phase stabilities of the 1:1 complexes are higher for the cations of small radii, in contrast to the solution stabilities. For cytosine and 9- methylhypoxantine the 1:1 complexes of their deprotonated forms are observed at higher cone voltage as a result of HCl molecule loss from the complexes containing the counter ion (Cl(-)). In solution, more stable complexes are formed with metal cations of low radii. Gas-phase stability of the complexes formed by deprotonated 9- methyl-hypoxantine increases with increasing metal cation radius.

  16. Synthesis of novel cationic lipids with fully or partially non-scissile ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 114; Issue 3. Synthesis of novel cationic lipids with fully or ... Keywords. Cationic lipids; non-scissile linkages; glycerol backbone; membranes; gene transfection. ... have been synthesized. The membrane-forming properties of these new lipids are briefly presented.

  17. Kinetics of styrene type radical cations generated by different ionization procedures

    International Nuclear Information System (INIS)

    Brede, O.; David, Frank

    1996-01-01

    In this paper the results from time-resolved experiments (pulse radiolysis, laser photolysis) on the formation of radical cations derived from styrene type olefins in solvents of different polarity are presented. The free olefin radical cations formed by charge transfer (in cyclohexane), two photon ionization or one electron oxidation (in aqueous solutions) dimerize to distonic radical cations or react with nucleophiles to produce benzyl type radicals. The decay of the dimer cation Ar-C·H-CH 2 -CH 2 -C + H-Ar seems to be determined by their ionic state: cationic polymerization in the case of free radical cations (one electron transfer ionization of styrenes), and intramolecular rearrangement to molecular dimer structures in the presence of counter ions [triplet sensitized electron transfer as reported by [Schepp and Johnston (1994) J. Am. Chem. Soc. 116, 6895]. (Author)

  18. On the mobility of exchangeable cations on clay surfaces

    International Nuclear Information System (INIS)

    Gimmi, T.; Kosakowski, G.; Glaus, M.A.

    2010-01-01

    Document available in extended abstract form only. The diffusive mobility of radionuclides in buffer materials and potential host rocks is an important topic in the safety analysis for underground waste repositories. Many of the radionuclides are cations. Accordingly, the diffusion and retention of cations in compacted clay minerals and clay rocks is of central interest. The retention properties of the clay minerals originate from their negative surface charges. These are compensated by un-specifically sorbed cations that are located on planar surfaces or in interlayers (exchangeable cations) and by cations that are more specifically sorbed for instance to edge sites. In general, sorbed cations are considered as immobile with respect to diffusive transport. Whereas this may be correct for specifically sorbed cations, this is probably not the case for un-specifically sorbed exchangeable cations. They can easily exchange with cations in the pore solution, even if they are located- at low hydration states-in very narrow interlayers. For such exchange a certain mobility in the sorbed state is required. This is in line with the observations that many experimentally derived cation diffusion coefficients are larger than expected when compared with those of water tracers. This and the dependence of effective diffusion coefficients on the external salt concentration can be explained with so-called surface diffusion, that is, a movement of sorbed cations. Unfortunately, no direct proof of this phenomenon is available, and parameters like surface diffusion coefficients or surface mobilities are largely unknown. We compiled a large number of published cation diffusion coefficients for various clay minerals and clay rocks. We showed that by an appropriate scaling of the cation diffusion coefficients, it is possible to estimate the average surface mobility of the cation in each experiment. We define the surface mobility as the surface diffusion coefficient of a cation on a flat

  19. Oxy-Allyl Cation Catalysis: An Enantioselective Electrophilic Activation Mode

    Science.gov (United States)

    Liu, Chun; Oblak, E. Zachary; Vander Wal, Mark N.; Dilger, Andrew K.; Almstead, Danielle K.; MacMillan, David W. C.

    2016-01-01

    A generic activation mode for asymmetric LUMO-lowering catalysis has been developed using the long-established principles of oxy-allyl cation chemistry. Here, the enantioselective conversion of racemic α-tosyloxy ketones to optically enriched α-indolic carbonyls has been accomplished using a new amino alcohol catalyst in the presence of electron-rich indole nucleophiles. Kinetic studies reveal that the rate-determining step in this SN1 pathway is the catalyst-mediated α-tosyloxy ketone deprotonation step to form an enantiodiscriminant oxy-allyl cation prior to the stereodefining nucleophilic addition event. PMID:26797012

  20. Genomic saturation mutagenesis and polygenic analysis identify novel yeast genes affecting ethyl acetate production, a non-selectable polygenic trait

    Science.gov (United States)

    Abt, Tom Den; Souffriau, Ben; Foulquié-Moreno, Maria R.; Duitama, Jorge; Thevelein, Johan M.

    2016-01-01

    Isolation of mutants in populations of microorganisms has been a valuable tool in experimental genetics for decades. The main disadvantage, however, is the inability of isolating mutants in non-selectable polygenic traits. Most traits of organisms, however, are non-selectable and polygenic, including industrially important properties of microorganisms. The advent of powerful technologies for polygenic analysis of complex traits has allowed simultaneous identification of multiple causative mutations among many thousands of irrelevant mutations. We now show that this also applies to haploid strains of which the genome has been loaded with induced mutations so as to affect as many non-selectable, polygenic traits as possible. We have introduced about 900 mutations into single haploid yeast strains using multiple rounds of EMS mutagenesis, while maintaining the mating capacity required for genetic mapping. We screened the strains for defects in flavor production, an important non-selectable, polygenic trait in yeast alcoholic beverage production. A haploid strain with multiple induced mutations showing reduced ethyl acetate production in semi-anaerobic fermentation, was selected and the underlying quantitative trait loci (QTLs) were mapped using pooled-segregant whole-genome sequence analysis after crossing with an unrelated haploid strain. Reciprocal hemizygosity analysis and allele exchange identified PMA1 and CEM1 as causative mutant alleles and TPS1 as a causative genetic background allele. The case of CEM1 revealed that relevant mutations without observable effect in the haploid strain with multiple induced mutations (in this case due to defective mitochondria) can be identified by polygenic analysis as long as the mutations have an effect in part of the segregants (in this case those that regained fully functional mitochondria). Our results show that genomic saturation mutagenesis combined with complex trait polygenic analysis could be used successfully to

  1. Genomic saturation mutagenesis and polygenic analysis identify novel yeast genes affecting ethyl acetate production, a non-selectable polygenic trait

    Directory of Open Access Journals (Sweden)

    Tom Den Abt

    2016-03-01

    Full Text Available Isolation of mutants in populations of microorganisms has been a valuable tool in experimental genetics for decades. The main disadvantage, however, is the inability of isolating mutants in non-selectable polygenic traits. Most traits of organisms, however, are non-selectable and polygenic, including industrially important properties of microorganisms. The advent of powerful technologies for polygenic analysis of complex traits has allowed simultaneous identification of multiple causative mutations among many thousands of irrelevant mutations. We now show that this also applies to haploid strains of which the genome has been loaded with induced mutations so as to affect as many non-selectable, polygenic traits as possible. We have introduced about 900 mutations into single haploid yeast strains using multiple rounds of EMS mutagenesis, while maintaining the mating capacity required for genetic mapping. We screened the strains for defects in flavor production, an important non-selectable, polygenic trait in yeast alcoholic beverage production. A haploid strain with multiple induced mutations showing reduced ethyl acetate production in semi-anaerobic fermentation, was selected and the underlying quantitative trait loci (QTLs were mapped using pooled-segregant whole-genome sequence analysis after crossing with an unrelated haploid strain. Reciprocal hemizygosity analysis and allele exchange identified PMA1 and CEM1 as causative mutant alleles and TPS1 as a causative genetic background allele. The case of CEM1 revealed that relevant mutations without observable effect in the haploid strain with multiple induced mutations (in this case due to defective mitochondria can be identified by polygenic analysis as long as the mutations have an effect in part of the segregants (in this case those that regained fully functional mitochondria. Our results show that genomic saturation mutagenesis combined with complex trait polygenic analysis could be used

  2. Micronutrient Fortification of Foods

    African Journals Online (AJOL)

    Micronutrient Fortification of Foods: Developing A Program. Mahshid Lotti, M.G. Venkatesh Manar, Richard J. H. M. .... Develop the fortification technology. 11. Perform studies on interactions, potency, stability, ... Fortification with vitamin A is a long-term strategy capable of maintaining adequate vitamin A status over time.

  3. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  4. EXPERIENCE OF USING A NON-SELECTIVE BETA-BLOCKER IN COMPLEX THERAPY OF REPOLARIZATION DISORDERS IN YOUNG ATHLETES

    Directory of Open Access Journals (Sweden)

    A. Yu. Tikhomirov

    2017-01-01

    Full Text Available Purpose. To study the effectiveness of various schemes of correction of repolarization disorder syndrome, including with the use of beta-blockers, in young athletes of the initial training group.Materials and methods. At the first stage, 410 children involved in sports sections were examined. The average age of the examined was 12.22 ± 3.11 years. At the second stage, the athletes (boys of the initial training group were selected from the surveyed contingent, engaged in martial arts. The groups were formed: A – people with violation of myocardial repolarization processes (72 patients, the average age 10,50 ± 0,35 years, the control group – people without changes in an electrocardiogram (33 people, the average age 10.36 ± 0, 62 years old. All underwent an electrocardiographic study at rest and after physical activity on the Innomed HS80GL apparatus with analysis of the main indicators. The vegetative status and the state of adaptation were estimated by Kerdo index and adaptive potential by Baevsky. After the examination, the subgroup A1 (40 people was prescribed metabolic and antioxidant drugs. Additionally, in the subgroup A2 (32 people, a non-selective beta-blocker was included in the treatment regimen. The course of treatment is 10 days. The analysis of indicators was carried out in 10 days and in a month after the initiation treatment. Statistical processing was carried out in the program Statistica.Results. An earlier disappearance of cardialgia was determined in the subgroup A2 (p < 0.05, whereas in the subgroup A1, 5% of patients had complaints not only at the end of the course, but also a month later after the initiation treatment. The more rapid positive dynamics of the electrocardiographic pattern with a more stable result was observed with the prescription of a beta-blocker.Conclusion. It was proved the advisability of prescribing of beta-blockers in the treatment of beginning athletes with violation of myocardial repolarization

  5. Metal Cationization Extractive Electrospray Ionization Mass Spectrometry of Compounds Containing Multiple Oxygens

    Science.gov (United States)

    Swanson, Kenneth D.; Spencer, Sandra E.; Glish, Gary L.

    2017-06-01

    Extractive electrospray ionization is an ambient ionization technique that allows real-time sampling of liquid samples, including organic aerosols. Similar to electrospray ionization, the composition of the electrospray solvent used in extractive electrospray ionization can easily be altered to form metal cationized molecules during ionization simply by adding a metal salt to the electrospray solvent. An increase in sensitivity is observed for some molecules that are lithium, sodium, or silver cationized compared with the protonated molecule formed in extractive electrospray ionization with an acid additive. Tandem mass spectrometry of metal cationized molecules can also significantly improve the ability to identify a compound. Tandem mass spectrometry of lithium and silver cationized molecules can result in an increase in the number and uniqueness of dissociation pathways relative to [M + H]+. These results highlight the potential for extractive electrospray ionization with metal cationization in analyzing complex aerosol mixtures. [Figure not available: see fulltext.

  6. Synthesis of novel cationic lipids with fully or partially non-scissile ...

    Indian Academy of Sciences (India)

    Abstract. Five novel cationic lipids with fully or partially non-scissile linkage regions between the pseudoglyceryl backbone and the hydrocarbon chains have been synthesized. The membrane-forming properties of these new lipids are briefly presented.

  7. Differences in exam performance between pupils attending selective and non-selective schools mirror the genetic differences between them

    Science.gov (United States)

    Smith-Woolley, Emily; Pingault, Jean-Baptiste; Selzam, Saskia; Rimfeld, Kaili; Krapohl, Eva; von Stumm, Sophie; Asbury, Kathryn; Dale, Philip S.; Young, Toby; Allen, Rebecca; Kovas, Yulia; Plomin, Robert

    2018-03-01

    On average, students attending selective schools outperform their non-selective counterparts in national exams. These differences are often attributed to value added by the school, as well as factors schools use to select pupils, including ability, achievement and, in cases where schools charge tuition fees or are located in affluent areas, socioeconomic status. However, the possible role of DNA differences between students of different schools types has not yet been considered. We used a UK-representative sample of 4814 genotyped students to investigate exam performance at age 16 and genetic differences between students in three school types: state-funded, non-selective schools (`non-selective'), state-funded, selective schools (`grammar') and private schools, which are selective (`private'). We created a genome-wide polygenic score (GPS) derived from a genome-wide association study of years of education (EduYears). We found substantial mean genetic differences between students of different school types: students in non-selective schools had lower EduYears GPS compared to those in grammar (d = 0.41) and private schools (d = 0.37). Three times as many students in the top EduYears GPS decile went to a selective school compared to the bottom decile. These results were mirrored in the exam differences between school types. However, once we controlled for factors involved in pupil selection, there were no significant genetic differences between school types, and the variance in exam scores at age 16 explained by school type dropped from 7% to <1%. These results show that genetic and exam differences between school types are primarily due to the heritable characteristics involved in pupil admission.

  8. Cation-Coupled Bicarbonate Transporters

    OpenAIRE

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 ...

  9. On the definition of the detection limit for non-selective determination of low activities

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1977-01-01

    Based on the latest published results, a detection limit which is easy to use in practical work without intensive consideration of counting statistics, is presented. The primary application of the given definition is the determination of gross activity. In the definition the error of the second kind as well as one-sided boundedness of the normal distribution are included. The results are given in graphical form. (orig.) [de

  10. Formation and reactions of radical cations of substituted benzenes in aqueous media

    International Nuclear Information System (INIS)

    Holcman, J.

    1977-08-01

    Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH - , either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH - and Fe 2+ , or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH - , together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)

  11. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...... and concepts from real designs by studying form in abstract contexts. The challenge for the first approach is how to support students in decoupling form from the work as a whole. The challenge for the second approach is how to translate general form into real design. Hence, choosing between the two approaches...

  12. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    Science.gov (United States)

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  13. Study of ionic liquid cations transport in soil.

    Science.gov (United States)

    Studzińska, Sylwia; Kowalkowski, Tomasz; Buszewski, Bogusław

    2009-09-15

    Ionic liquids are a form of organic or inorganic molten salts consisting positive and negative ions. There have been several attempts of their utilization in industry. These substances can be released from industrial sites into water and soils thus causing contamination. The most significant chemical processes affecting the behavior of ionic liquid cations in soils are related to their transport. The major aim of this work was to investigate the transport process of imidazolium ionic liquids in soils by column leaching experiments. Five types of soil with varying total organic carbon (TOC) content (chlorides namely: 1-ethyl-3-methylimidazolium (EMIM), 1-n-butyl-3-methylimidazolium (BMIM), 1-n-hexyl-3-methylimidazolium (HMIM). The results obtained indicated significant ability to immobilize ionic liquid cations by soils with higher organic carbon content. The higher TOC value in soil results in lower amounts of solutes migrating through the soil. Factorial regression has been applied to modeling of the results. It relates soil and the ionic liquid cation properties to the retardation of this cation in soil profile.

  14. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chih-Jen [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jean, Jiin-Shuh; Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca{sup 2+} as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK{sub a2} (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d{sub 001}) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  15. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-09-01

    This review is focused on the structural and physico-chemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-Quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm.

  16. Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

    Full Text Available The fusion pore is an aqueous channel that is formed upon the fusion of the vesicle membrane with the plasma membrane. Once the pore is open, it may close again (transient fusion or widen completely (full fusion to permit vesicle cargo discharge. While repetitive transient fusion pore openings of the vesicle with the plasma membrane have been observed in the absence of stimulation, their frequency can be further increased using a cAMP-increasing agent that drives the opening of nonspecific cation channels. Our model hypothesis is that the openings and closings of the fusion pore are driven by changes in the local concentration of cations in the connected vesicle. The proposed mechanism of fusion pore dynamics is considered as follows: when the fusion pore is closed or is extremely narrow, the accumulation of cations in the vesicle (increased cation concentration likely leads to lipid demixing at the fusion pore. This process may affect local membrane anisotropy, which reduces the spontaneous curvature and thus leads to the opening of the fusion pore. Based on the theory of membrane elasticity, we used a continuum model to explain the rhythmic opening and closing of the fusion pore.

  17. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite.

    Science.gov (United States)

    Wang, Chih-Jen; Li, Zhaohui; Jiang, Wei-Teh; Jean, Jiin-Shuh; Liu, Chia-Chuan

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca(2+) as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK(a2) (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d(001)) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Electrodeposition properties of modified cational epoxy resin-type photoresist

    International Nuclear Information System (INIS)

    Yong He; Yunlong Zhang; Feipeng Wu; Miaozhen Li; Erjian Wang

    1999-01-01

    Multi-component cationic epoxy and acrylic resin system for ED photoresist was used in this work, since they can provide better storage stability for ED emulsion and better physical and chemical properties of deposited film than one-component system. The cationic main resin (AE) was prepared from amine modified epoxy resins and then treated with acetic acid. The amination degree was controlled as required. The synthetic procedure of cationic main resins is described in scheme I. The ED photoresist (AME) is composed of cationic main resin (AE) and nonionic multifunctional acrylic crosslinkers (PETA), in combination with suitable photo-initiator. They can easily be dispersed in deionized water to form a stable ED emulsion. The exposed part of deposited film upon UV irradiation occurs crosslinking to produce an insoluble semi-penetrating network and the unexposed part remains good solubility in the acidic water solution. It is readily utilized for fabrication of fine micropattern. The electrodeposition are carried out on Cu plate at room temperature. To evaluate the electrodeposition properties of ED photoresist (AME), the different influences are examined

  19. Cation-Pi Interaction: A Key Force for Sorption of Fluoroquinolone Antibiotics on Pyrogenic Carbonaceous Materials.

    Science.gov (United States)

    Zhao, Qing; Zhang, Siyu; Zhang, Xuejiao; Lei, Lei; Ma, Wei; Ma, Chuanxin; Song, Lei; Chen, Jingwen; Pan, Bo; Xing, Baoshan

    2017-12-05

    Cation-pi attraction is a major force that determines macromolecular structures and drug-receptor interactions. However, the role of the cation-pi interaction in sorption of fluoroquinolone antibiotics by pyrogenic carbonaceous materials (PCMs) has not been addressed. We studied sorption of ciprofloxacin (CIP) on graphite to quantify the contribution of the cation-pi interaction. Through competition experiments, the decreased amount of sorbed CIP by sequential treatment with hexadecane, phenanthrene and benzylamine represents the contribution of hydrophobic, pi-pi and cation-pi interactions, respectively. Benzylamine competed more strongly with CIP than n-hexadecane and phenanthrene, indicating that cation-pi is a major force. Cation-pi interactions accounted for up to 72.6% of the total sorption at an initial CIP concentration of 0.000015 mmol/L. Importantly, species transformation (CIP(0) captures H + from water to form CIP(+1)) induced by cation-pi interactions was verified both experimentally and theoretically and can be used to explain the environmental behavior of other fluoroquinolone antibiotics and biochemical processes of amino acids that interact with aromatic moieties. Because of the significant role of cation-pi interactions, CIP desorption increased up to 2.32 times when Na + increased from 0.01 mM to 0.45 mM, which is an environmentally relevant scenario at river estuaries. Hence, behaviors of fluoroquinolone antibiotics that are affected by ionic strength changes need to be carefully evaluated, especially in river estuaries.

  20. Primary processes of the radiation-induced cationic polymerization of aromatic olefins studied by pulse radiolysis

    International Nuclear Information System (INIS)

    Brede, O.; Boes, J.; Helmstreit, W.; Mehnert, R.

    1982-01-01

    By pulse radiolysis of solutions of aromatic olefins (styrene, 1-methylstyrene, 1,1-diphenylethylene) in non-polar solvents (cyclohexane, carbon tetrachloride, n-butylchloride) the mechanism and kinetics of primary processes of radiation-induced cationic polymerization were investigated. In cyclohexane, radical cations of the olefins are generated by charge transfer from solvent cations. These cations dimerize in a diffusion-controlled reaction. The next step of chain-growth is slower by 3 to 4 orders of magnitude. In carbon tetrachloride and in n-butyl chloride growing olefin cations are produced by a reaction of radical cations with solvent as well as by addition of solvent carbonium ions to the monomer. In strongly acidic aqueous solution of olefins radical cations produced indirectly from hydroxycyclohexadienyl radicals dimerize and react in a subsequent step by deprotonation forming non-saturated dimer radicals. The reaction mechanism established shows that in the case of radiation-induced cationic polymerization it is not possible to define a uniform first step of the chain reaction. (author)

  1. Primary processes of the radiation-induced cationic polymerization of aromatic olefins studied by pulse radiolysis

    International Nuclear Information System (INIS)

    Brede, O.; Boes, J.; Helmstreit, W.; Mehnert, R.

    1981-01-01

    By pulse radiolysis of solutions of aromatic olefins (styrene, 1-methylstyrene, 1,1-diphenylethylene) in nonpolar solvents (cyclohexane, carbon tetrachloride, n-butyl chloride) the mechanism and kinetics of primary processes of radiation-induced cationic polymerization were investigated. In cyclohexane, radical cations of the olefins are generated by charge transfer from solvent cations (k about 10 11 l mol -1 s -1 ). These cations dimerize in a diffusion-controlled reaction (k approximately 10 10 l mol -1 s -1 ). The next step of chain-growth is slower by 3 to 4 orders of magnitude. Furthermore, in carbon tetrachloride and in n-butyl chloride growing olefin cations are produced by a reaction of the radical cations with the solvent as well as by addition of solvent carbonium ions to the monomer. In strongly acidic aqueous solution of olefins radical cations produced indirectly from hydroxycyclohexadienyl radicals dimerize and react in a subsequent step by deprotonation forming non-saturated dimer radicals. The established reaction mechanism shows that in the case of radiation-induced cationic polymerization it is not possible to define a uniform first step of the chain reaction. (author)

  2. Coordination of lanthanide cation to an Anderson type ...

    Indian Academy of Sciences (India)

    For correspondence lanthanide cations. In 2002, we reported a prelimi- nary result14 on “a polyoxometalate chain formed from heteropolyanion building blocks and rare earth metal ion linkers: [La(H2O)7Al(OH)6Mo6O18]n · 4nH2O”, in which we mentioned that “this material provides an opportunity to synthesize a new class ...

  3. Model of Selective and Non-Selective Management of Badgers (Meles meles) to Control Bovine Tuberculosis in Badgers and Cattle.

    Science.gov (United States)

    Smith, Graham C; Delahay, Richard J; McDonald, Robbie A; Budgey, Richard

    2016-01-01

    Bovine tuberculosis (bTB) causes substantial economic losses to cattle farmers and taxpayers in the British Isles. Disease management in cattle is complicated by the role of the European badger (Meles meles) as a host of the infection. Proactive, non-selective culling of badgers can reduce the incidence of disease in cattle but may also have negative effects in the area surrounding culls that have been associated with social perturbation of badger populations. The selective removal of infected badgers would, in principle, reduce the number culled, but the effects of selective culling on social perturbation and disease outcomes are unclear. We used an established model to simulate non-selective badger culling, non-selective badger vaccination and a selective trap and vaccinate or remove (TVR) approach to badger management in two distinct areas: South West England and Northern Ireland. TVR was simulated with and without social perturbation in effect. The lower badger density in Northern Ireland caused no qualitative change in the effect of management strategies on badgers, although the absolute number of infected badgers was lower in all cases. However, probably due to differing herd density in Northern Ireland, the simulated badger management strategies caused greater variation in subsequent cattle bTB incidence. Selective culling in the model reduced the number of badgers killed by about 83% but this only led to an overall benefit for cattle TB incidence if there was no social perturbation of badgers. We conclude that the likely benefit of selective culling will be dependent on the social responses of badgers to intervention but that other population factors including badger and cattle density had little effect on the relative benefits of selective culling compared to other methods, and that this may also be the case for disease management in other wild host populations.

  4. The modulation of TRPM7 currents by nafamostat mesilate depends directly upon extracellular concentrations of divalent cations

    Directory of Open Access Journals (Sweden)

    Chen Xuanmao

    2010-12-01

    Full Text Available Abstract Concentrations of extracellular divalent cations (Ca2+ and Mg2+ fall substantially during intensive synaptic transmission as well as during some pathophysiological conditions such as epilepsy and brain ischemia. Here we report that a synthetic serine protease inhibitor, nafamostat mesylate (NM, and several of its analogues, block recombinant TRPM7 currents expressed in HEK293T cells in inverse relationship to the concentration of extracellular divalent cations. Lowering extracellular Ca2+ and Mg2+ also evokes a divalent-sensitive non-selective cation current that is mediated by TRPM7 expression in hippocampal neurons. In cultured hippocampal neurons, NM blocked these TRPM7-mediated currents with an apparent affinity of 27 μM, as well as the paradoxical Ca2+ influx associated with lowering extracellular Ca2+. Unexpectedly, pre-exposure to NM strongly potentiated TRPM7 currents. In the presence of physiological concentrations of extracellular divalent cations, NM activates TRPM7. The stimulating effects of NM on TRPM7 currents are also inversely related to extracellular Ca2+ and Mg2+. DAPI and HSB but not netropsin, blocked and stimulated TRPM7. In contrast, mono-cationic, the metabolites of NM, p-GBA and AN, as well as protease inhibitor leupeptin and gabexate failed to substantially modulate TRPM7. NM thus provides a molecular template for the design of putative modulators of TRPM7.

  5. Randomized trial of switching from prescribed non-selective non-steroidal anti-inflammatory drugs to prescribed celecoxib

    DEFF Research Database (Denmark)

    Macdonald, Thomas M; Hawkey, Chris J; Ford, Ian

    2017-01-01

    BACKGROUND: Selective cyclooxygenase-2 inhibitors and conventional non-selective non-steroidal anti-inflammatory drugs (nsNSAIDs) have been associated with adverse cardiovascular (CV) effects. We compared the CV safety of switching to celecoxib vs. continuing nsNSAID therapy in a European setting...... infarction or other biomarker positive acute coronary syndrome, non-fatal stroke or CV death analysed using a Cox model with a pre-specified non-inferiority limit of 1.4 for the hazard ratio (HR). RESULTS: In total, 7297 participants were randomized. During a median 3-year follow-up, fewer subjects than...

  6. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  7. Formation and reactions of cation-radicals of aliphatic ketones in freon matrices at low temperatures

    International Nuclear Information System (INIS)

    Belevskii, V.N.; Belopushkin, S.I.; Fel'dman, V.I.

    1988-01-01

    In solutions of acetone and methyl ethyl ketone in CFCl 3 (0.1-22%) γ-irradiated at 77 K, monomeric and dimeric cation-radicals of the ketones, as well as RCHCOMe radicals, are stabilized with yields dependent on the ketone concentration in the CFCl 3 . On exposure to light the dimeric cation-radicals are converted to RCHCOMe while the monomers disappear without forming radicals. It is shown that different types of ion-molecule reactions occur in the solid phase in which the monomeric and dimeric cation-radicals participate

  8. Optimization of divalent cation in Saccharomyces pastorianus ...

    African Journals Online (AJOL)

    Cassava starch fermentations were conducted in batch cultures to optimize the effect of divalent cations on ethanol production with Saccharomyces pastorianus using the central composite rotatable response surface design. Divalent cations used were magnesium (Mg2+), zinc (Zn2+) and calcium (Ca2+). Maximum ethanol ...

  9. The human red cell voltage-dependent cation channel. Part III: Distribution homogeneity and pH dependence

    DEFF Research Database (Denmark)

    Bennekou, P.; Barksmann, T. L.; Christophersen, P.

    2006-01-01

    The homogeneity of the distribution of the non-selective voltage-dependent cation channel (the NSVDC channel) in the human erythrocyte, and the pH dependence was investigated. Activation of this channel caused a uniform cellular dehydration, which was characterized by the changes in the erythrocy...... - but not the extracellular - pH. The apparent pKA value for the effect was estimated to be 6.5, and the specific histidine reagent 2.4'-dibromoacetophenone (DBAB) inactivated the NSVDC channel....

  10. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  11. Intracellular trafficking mechanism of cationic phospholipids including cationic liposomes in HeLa cells.

    Science.gov (United States)

    Un, K; Sakai-Kato, K; Goda, Y

    2014-07-01

    The development of gene delivery methods is essential for the achievement of effective gene therapy. Elucidation of the intracellular transfer mechanism for cationic carriers is in progress, but there are few reports regarding the intracellular trafficking processes of the cationic phospholipids taken up into cells. In the present work, the trafficking processes of a cationic phospholipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) were investigated from intracellular uptake to extracellular efflux using cationic liposomes in vitro. Following intracellular transport of liposomes via endocytosis, DOTAP was localized in the endoplasmic reticulum, Golgi apparatus, and mitochondria. Moreover, the proteins involved in DOTAP intracellular trafficking and extracellular efflux were identified. In addition, helper lipids of cationic liposomes were found to partially affect this intracellulartrafficking. These findings might provide valuable information for designing cationic carriers and avoiding unexpected toxic side effects derived from cationic liposomal components.

  12. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.

    2014-01-01

    temperature, but ethanesulfonate imidazolium and pyridinium oligomeric ionic liquids form a low melting crystalline phase. The proton conductivities of the oligomeric ionic liquids are determined by the type of cation in the temperature range 80-120 degrees C under anhydrous conditions and vary within five......Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...... derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room...

  13. Broadband non-selective excitation of plutonium isotopes for isotope ratio measurements in resonance ionization mass spectrometry: a theoretical study.

    Science.gov (United States)

    Sankari, M

    2012-10-15

    Making isotope ratio measurements with minimum isotope bias has always been a challenging task to mass spectrometrists, especially for the specific case of plutonium, owing to the strategic importance of the element. In order to use resonance ionization mass spectrometry (RIMS) as a tool for isotope ratio measurements, optimization of the various laser parameters and other atomic and system parameters is critical to minimize isotopic biases. Broadband simultaneous non-selective excitation of the isotopes of plutonium in the triple resonance excitation scheme with λ(1) = 420.77 nm, λ(2) = 847.28 nm, and λ(3) = 767.53 nm based on density matrix formalism has been theoretically computed for the determination of isotope ratios. The effects of the various laser parameters and other factors such as the atomization temperature and the dimensions of the atomic beam on the estimation of isotope ratios were studied. The effects of Doppler broadening, and time-dependent excitation parameters such as Rabi frequencies, ionization rate and the effect of non-Lorenztian lineshape have all been incorporated. The average laser powers and bandwidths for the three-excitation steps were evaluated for non-selective excitation. The laser intensity required to saturate the three-excitation steps were studied. The two-dimensional lineshape contour and its features were investigated, while the reversal of peak asymmetry of two-step and two-photon excitation peaks under these conditions is discussed. Optimized powers for the non-selective ionization of the three transitions were calculated as 545 mW, 150 mW and 545 mW and the laser bandwidth for all the three steps was ~20 GHz. The isotopic bias between the resonant and off-resonant isotope under the optimized conditions was no more than 9%, which is better than an earlier reported value. These optimized laser power and bandwidth conditions are better than in the earlier experimental work since these comprehensive calculations yield

  14. Cation transport in isomeric pentanes

    International Nuclear Information System (INIS)

    Gyoergy, Istvan; Gee, Norman; Freeman, G.R.

    1985-01-01

    The cation mobility μsub(+) is measured in n-pentane, isopentane, neo-pentane, and mixtures of n- and neo-pentane over conditions from the normal liquid, through the critical fluid, to the low density gas. Most of the liquid data correlate with the reduced temperature T/Tsub(c). The T/Tsub(c) reflects free volume and viscosity changes. Comparison is made to neutral molecule diffusion. The transition from viscosity control of mobility in the liquid to density control in the dilute gas occurs over the reduced viscosity region 3 > eta/etasub(c) > 0.6, which corresponds to the reduced density region 1.9 > eta/etasub(c) > 0.5. In the saturated gas etaμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average gas nμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average momentum transfer cross sections in the n-/neo-pentane mixtures are similar to those in neo-pentane at low T but similar to those in n-pentane at high T. The present findings are combined with previous electron mobility data in addressing the effect of hydrocarbon molecular (external) shape on the electric breakdown strength of gases

  15. The effect of ultralow temperature on olefin cation formation by ionic fragmentation in the radiolysis of 2,3-dimethylbutane

    International Nuclear Information System (INIS)

    Miyazaki, Tetsuo

    1991-01-01

    The formation of olefin cations in the radiolysis of 2,3-dimethylbutane (DMB) was studied by ESR at 4.2 and 77 K. When a DMB-SF 6 mixture is γ-irradiated at 77 K, tetramethylethylene (TME) cations are formed remarkably. The formation of the TME cations, however, is suppressed at 4.2 K. When the DMB-SF 6 mixture is γ-irradiated at 4.2 K and then warmed to 77 K, TME cations are formed by thermal annealing. The TME cations are not formed by a charge transfer to olefinic impurities or olefinic products in radiolysis, but by H 2 elimination from parent DMB cations in the ground state. The remarkable formation of olefin cations at 77 K corresponds to the large yields of unsaturated dimers in the radiolysis of DMB at 77 K. The suppression of olefin cation formation at 4.2 K corresponds to the low yields of unsaturated dimers in the radiolysis of DMB at 4.2 K. (author)

  16. Formation of radical cations in a model for the metabolism of aromatic hydrocarbons

    International Nuclear Information System (INIS)

    Lehner, Andreas F.; Horn, Jamie; Flesher, James W.

    2004-01-01

    To test the hypothesis that electrophilic radical cations are the major ultimate electrophilic and carcinogenic forms of benz[a]anthracene (BA), dibenz[a,h]anthracene (DBA), and benzo[a]pyrene (BP), we have focused on a chemical model of metabolism which parallels and duplicates known or potential metabolites of some polycyclic hydrocarbons formed in cells. Studies of this model system show that radical cations are hardly formed, if at all, in the case of BA or DBA but are definitely formed in the cases of the carcinogen BP as well as the non-carcinogenic hydrocarbons, pyrene and perylene. We conclude that the carcinogenicities of BA, DBA, BP, pyrene, and perylene are independent of one-electron oxidation to radical cation intermediates

  17. Use of non-selective β-blockers is associated with decreased tumor proliferative indices in early stage breast cancer.

    Science.gov (United States)

    Montoya, Alexa; Amaya, Clarissa N; Belmont, Andres; Diab, Nabih; Trevino, Richard; Villanueva, Geri; Rains, Steven; Sanchez, Luis A; Badri, Nabeel; Otoukesh, Salman; Khammanivong, Ali; Liss, Danielle; Baca, Sarah T; Aguilera, Renato J; Dickerson, Erin B; Torabi, Alireza; Dwivedi, Alok K; Abbas, Aamer; Chambers, Karinn; Bryan, Brad A; Nahleh, Zeina

    2017-01-24

    Previous studies suggest beta-adrenergic receptor (β-AR) antagonists (β-blockers) decrease breast cancer progression, tumor metastasis, and patient mortality; however the mechanism for this is unknown. Immunohistochemical analysis of normal and malignant breast tissue revealed overexpression of β1-AR and β3-AR in breast cancer. A retrospective cross-sectional study of 404 breast cancer patients was performed to determine the effect of β-blocker usage on tumor proliferation. Our analysis revealed that non-selective β-blockers, but not selective β-blockers, reduced tumor proliferation by 66% (p breast cancer compared to non-users. We tested the efficacy of propranolol on an early stage breast cancer patient, and quantified the tumor proliferative index before and after treatment, revealing a propranolol-mediated 23% reduction (p = 0.02) in Ki67 positive tumor cells over a three-week period. The anti-proliferative effects of β-blockers were measured in a panel of breast cancer lines, demonstrating that mammary epithelial cells were resistant to propranolol, and that most breast cancer cell lines displayed dose dependent viability decreases following treatment. Selective β-blockers alone or in combination were not as effective as propranolol at reducing breast cancer cell proliferation. Molecular analysis revealed that propranolol treatment of the SK-BR-3 breast cancer line, which showed high sensitivity to beta blockade, led to a reduction in Ki67 protein expression, decreased phosphorylation of the mitogenic signaling regulators p44/42 MAPK, p38 MAPK, JNK, and CREB, increased phosphorylation of the cell survival/apoptosis regulators AKT, p53, and GSK3β. In conclusion, use of non-selective β-blockers in patients with early stage breast cancer may lead to decreased tumor proliferation.

  18. Simultaneous electrochemical-electron spin resonance studies of carotenoid cation radicals and dications

    International Nuclear Information System (INIS)

    Khaled, M.; Hadjipetrou, A.; Xinhai Chen; Kispert, L.

    1989-01-01

    Carotenoids are present in the chloroplasts of photosynthetic green plants and serve as photoprotect devices and antenna pigments, and active role in the photosynthetic electron-transport chain with the carotenoid cation radical as an integral part of the electron-transfer process. The research reported herein has confirmed that carotenoid cation radicals have a lifetime that is sensitive to solvent, being longest in CH 2 Cl 2 and are best prepared electrochemically. Semiempirical AM1 and INDO calculations of the trans and cis isomers of β-carotene, canthaxanthin and β-apo-8'-carotenal cation radicals predicted the unresolved EPR line whose linewidth varies to a measurable degree with carotenoid, which subsequent experimental observations affirmed. Simultaneous electrochemical - electron spin resonance studies of carotenoid cation radicals and dications have shown the radicals detected by EPR are formed by the one electron oxidation of the carotenoid, that dimers are not formed upon decay of the radical cations and an estimate of the rate of comproportionation as a function of carotenoid can be given. The formal rate constant K' for heterogenous electron transfer rate at the electrode surface has been deduced from rotating disc experiments. Upon deuteration, and in the presence of excess β-carotene, the half-life for decay of the carotenoid radical cation increased an order of magnitude due to the reaction between diffusion carotenoid dications and carotenoids to form additional radical cations. The carotenoid diffusion coefficients deduced by chronocoulometry substantiates this measurement. The produces formed upon electrochemical studies are being studied by HPLC and the isomers formed thermally are being separated. Additional radical reactions are currently being studied by EPR and electrochemical methods

  19. Arginine-based cationic liposomes for efficient in vitro plasmid DNA delivery with low cytotoxicity

    Directory of Open Access Journals (Sweden)

    Sarker SR

    2013-04-01

    Full Text Available Satya Ranjan Sarker, Yumiko Aoshima, Ryosuke Hokama, Takafumi Inoue, Keitaro Sou, Shinji Takeoka Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns, Tokyo, Japan Background: Currently available gene delivery vehicles have many limitations such as low gene delivery efficiency and high cytotoxicity. To overcome these drawbacks, we designed and synthesized two cationic lipids comprised of n-tetradecyl alcohol as the hydrophobic moiety, 3-hydrocarbon chain as the spacer, and different counterions (eg, hydrogen chloride [HCl] salt or trifluoroacetic acid [TFA] salt in the arginine head group. Methods: Cationic lipids were hydrated in 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES buffer to prepare cationic liposomes and characterized in terms of their size, zeta potential, phase transition temperature, and morphology. Lipoplexes were then prepared and characterized in terms of their size and zeta potential in the absence or presence of serum. The morphology of the lipoplexes was determined using transmission electron microscopy and atomic force microscopy. The gene delivery efficiency was evaluated in neuronal cells and HeLa cells and compared with that of lysine-based cationic assemblies and Lipofectamine™ 2000. The cytotoxicity level of the cationic lipids was investigated and compared with that of Lipofectamine™ 2000. Results: We synthesized arginine-based cationic lipids having different counterions (ie, HCl-salt or TFA-salt that formed cationic liposomes of around 100 nm in size. In the absence of serum, lipoplexes prepared from the arginine-based cationic liposomes and plasmid (p DNA formed large aggregates and attained a positive zeta potential. However, in the presence of serum, the lipoplexes were smaller in size and negative in zeta potential. The morphology of the lipoplexes was vesicular. Arginine-based cationic liposomes with HCl-salt showed the

  20. Spectrophotometric studies on cation-cation interactions between Np(V) and Th(IV) cations in nitric acid medium

    International Nuclear Information System (INIS)

    Verma, P.K.; Pathak, P.N.; Bhattacharyya, A.; Prabhu, D.R.; Mohapatra, P.K.

    2014-01-01

    The higher-valent actinide cations exhibit fascinating coordination chemistry essentially due to the flexibility in their electronic structures. This is particularly applicable for the dioxo penta- and hexavalent lighter actinides such as U, Np, Pu, and Am. Even though the oxo moiety is assumed to be chemically inert in these cations, there are several studies which show that pentavalent Np cation (NpO 2 + ) displays a tendency of bonding with charged metal ions. This class of weak bond formation has been classified as cation-cation interactions (CCI). Initial studies suggested that these types of interactions of Np(V) with polyvalent metal ions are more probable in non complexing perchloric acid solutions. Majority of these studies have been performed in perchlorate media and the stability constant values have been calculated. On the other hand, these studies in nitric acid medium are rather few. Our recent spectrophotometric study has shown that Np(V) cation undergoes disproportionation reaction and the tendency for CCI becomes less favorable at elevated temperature in nitric acid media. This study has been extended for understanding possible CCI between Np(V)O 2 + and Th 4 + ions under varying conditions such as nitric acid (1-6 M HNO 3 ). Th concentration (up to 0.86 M), and temperature (293-343K). An attempt has been made to calculate the stability constant values and compare with those reported in other media

  1. Cationization of heparin for film applications

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.

    2015-01-01

    Roč. 115, 22 January (2015), s. 551-558 ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.219, year: 2015

  2. Development of a stable cation modified graphene oxide membrane for water treatment

    Science.gov (United States)

    Yu, Wenzheng; (Yet Yu, Tong; Graham, Nigel

    2017-12-01

    Membranes prepared from layers of graphene oxide (GO) offer substantial advantages over conventional materials for water treatment (e.g. greater flux), but the stability of GO membranes in water has not been achieved until now. In this study the behavior of GO membranes prepared with different quantities and species of cations has been investigated to establish the feasibility of their application in water treatment. A range of cation-modified GO membranes were prepared and exposed to aqueous solutions containing specific chemical constituents. In pure water, unmodified and Na-modified GO membranes were highly unstable, while GO membranes modified with multivalent cations were stable provided there were sufficient quantities of cations present; their relative capability to achieve GO stability was as follows: Al3+  >  Ca2+  >  Mg2+  >  Na+. It is believed that the mechanism of cross-linking, and membrane stability, is via metal-carboxylate chelates and cation-graphite surface interactions (cation-π interaction), and that the latter appears to increase with increasing cation valency. The instability of cation (Ca or Al)-modified GO membranes by NaCl solutions during permeation occurred as Na+ exchanged with the incorporated multivalent cations, but a high content of Al3+ in the GO membrane impeded Al3+/Na+ exchange and thus retained membrane stability. In solutions containing biopolymers representative of surface waters or seawater (protein and polysaccharide solutions), Ca-GO membranes (even with high Ca2+ content) were not stable, while Al-GO membranes were stable if the Al3+ content was sufficiently high; Al-formed membranes also had a greater flux than Ca-GO membranes.

  3. Pure zeolite exchange to synthetic zeolite characterized by XRD to produce cation exchange materials

    International Nuclear Information System (INIS)

    Zainab Ramli; Dewi Jamaliah Kamsiar; Hasidah Mohd Arsat

    2008-01-01

    In this study, natural mordenite was modified to other zeolites phases having low Si/ Al in order to increase the cation exchange capacity of the material. Modification was carried out hydrothermally at 100 degree Celsius in time range between 0 to 24 hours. The samples obtained were characterized by XRD and infrared spectroscopy. Results showed that a mixture of zeolite X and P were formed zeolite X was the dominant zeolite at 6 hrs heating time while zeolite P were dominant after 6 hrs. Ion Exchange capacity of natural mordenite, samples at 6 hr and 24 hrs heating, performed using Ca 2+ cation gave cation exchange in the decreasing order of 83.57 % , 72.50 %, 69.45 % for sample 24 hrs, 6 hrs and natural mordenite respectively. It indicates that sample having zeolite P phase is the best cation exchange capacity with 21 mg Ca 2+ / g zeolite with an increased of 23 % capacity compared to natural zeolite. (author)

  4. The structural variety of DNA-DPPC-divalent metal cation aggregates: SAXD and SANS study

    Science.gov (United States)

    Uhríková, D.; Pullmannová, P.; Kučerka, N.; Funari, S. S.; Teixeira, J.; Balgavý, P.

    2009-02-01

    We examine the structure of aggregates formed due to DNA interaction with dipalmitoylphosphatidylcholine (DPPC) in presence of Ca2+ and Zn2+ using small-angle synchrotron X-ray diffraction (SAXD) and neutron scattering (SANS). SAXD shows structural heterogeneity as a function of the cation concentration and temperature: At low cation concentration (˜1 mM), aggregates show two DPPC phases, one with a lateral segregation of DNA and cation, while higher cation concentration improves the DNA packing and the condensed lamellar phase is observed in DNA+DPPC+20mMion2+ aggregates. The SANS detected the dissolution of the condensed lamellar phase into unilamellar DPPC+Zn2+ vesicles due to gel ↦ liquid-crystal phase transition in DNA+DPPC+20mM Zn2+ aggregates with the short fragmented salmon sperm DNA.

  5. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  6. Cationic surfactants as the hydrolytic micellar catalysts

    OpenAIRE

    Janošcová, Petra

    2013-01-01

    Cationic surfactants as the hydrolytic micellar catalysts Petra Janošcová The effectiveness of hydrolytic cleavage of the pesticide fenitrothionin cationic surfactants micellar media has been tested. All used surfactants increased the rate of fenitrothionhydrolysis, which was the evidence of micellar catalysis. For some surfactants decreases has been evident at the highest rate of hydrolysis concentrations. It has been the result of a phenomenon called the effect of empty micelles. High hydro...

  7. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope...... of the reaction. Particularly, a formation of configurationally labile aminal centers with alkyl substituents has been a formidable challenge due to the enamine/imine equilibrium of electrophilic substrates. Herein, we report enantioselective nucleophilic addition reactions of potassium phthalimides to Boc-protected...

  8. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  9. Luminescent sulfides of monovalent and trivalent cations

    International Nuclear Information System (INIS)

    1975-01-01

    The invention discloses a family of luminescent materials or phosphors having a rhombohedral crystal structure and consisting essentially of a mixed host sulfide of at least one monovalent host cation and at least one trivalent host cation, and containing, for each mole of phosphor, 0.0005 to 0.05 mole of at least one activating cation. The monovalent host cations may be Na, K or Rb and Cs. The trivalent host cations may be Gd, La, Lu, Sc and Y. The activating cations may be one or more of trivalent As, Bi, Ce, Dy, Er, Pr, Sb, Sm, Tb and Tm; divalent Lu, Mn, Pb and Sn; and monovalent Ag, Cu and Tl. The novel phosphors may be used in devices to convert electron-beam, ultraviolet or x-ray energy to light in the visible spectrum. Such energy conversion can be employed for example in fluoroscopic screens, and in viewing screens of cathode-ray tubes and other electron tubes

  10. From cation to oxide: hydroxylation and condensation of aqueous complexes

    International Nuclear Information System (INIS)

    Jolivet, J.P.

    1997-01-01

    Hydroxylation, condensation and precipitation of metal cations in aqueous solution are briefly reviewed. Hydroxylation of aqueous complexes essentially depends on the format charge (oxidation state), the size and the pH of the medium. It is the step allowing the condensation reaction. Depending on the nature of complexes (aqua-hydroxo, oxo-hydroxo), the. mechanism of condensation is different, olation or ox-olation respectively. The first one leads to poly-cations or hydroxides more or less stable against dehydration. The second one leads to poly-anions or oxides. Oligomeric species (poly-cations, poly-anions) are form from charged monomer complexes while the formation of solid phases requires non-charged precursors. Because of their high lability, charged oligomers are never the precursors of solids phases. The main routes for the formation of solid phases from solution are studied with two important and representative elements, Al and Si. For Al 3+ ions, different methods (base addition in solution, thermo-hydrolysis, hydrothermal synthesis) are discussed in relation to the crystal structure of the solid phase obtained. For silicic species condensing by ox-olation, the role of acid or base catalysis on the morphology of gels is studied. The influence of complexing ligands on the processes and on the characteristics of solids (morphology of particles, basic salts and polymetallic oxides formation) is studied. (author)

  11. Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    P. Chmielarz

    2016-10-01

    Full Text Available Cyclodextrin-based cationic star polymers were synthesized using β-cyclodextrin (β-CD core, and 2-(dimethylamino ethyl methacrylate (DMAEMA as hydrophilic arms. Star-shaped polymers were prepared via a simplified electrochemically mediated ATRP (seATRP under potentiostatic and galvanostatic conditions. The polymerization results showed molecular weight (MW evolution close to theoretical values, and maintained narrow molecular weight distribution (MWD of obtained stars. The rate of the polymerizations was controlled by applying more positive potential values thereby suppressing star-star coupling reactions. Successful chain extension of the ω-functional arms with a hydrophobic n-butyl acrylate (BA formed star block copolymers and confirmed the living nature of the β-CD-PDMAEMA star polymers prepared by seATRP. Novelty of this work is that the β-CD-PDMAEMA-b-PBA cationic star block copolymers were synthesized for the first time via seATRP procedure, utilizing only 40 ppm of catalyst complex. The results from 1H NMR spectral studies support the formation of cationic star (copolymers.

  12. Cation Exchange in the Presence of Oil in Porous Media

    NARCIS (Netherlands)

    Farajzadeh, R.; Guo, H.; van Winden, J.L.; Bruining, J.

    2017-01-01

    Cation exchange is an interfacial process during which cations on a clay surface are replaced by other cations. This study investigates the effect of oil type and composition on cation exchange on rock surfaces, relevant for a variety of oil-recovery processes. We perform experiments in which brine

  13. Detergent-like actions of linear amphipathic cationic antimicrobial peptides.

    Science.gov (United States)

    Bechinger, Burkhard; Lohner, Karl

    2006-09-01

    Antimicrobial peptides have raised much interest as pathogens become resistant against conventional antibiotics. We review biophysical studies that have been performed to better understand the interactions of linear amphipathic cationic peptides such as magainins, cecropins, dermaseptin, delta-lysin or melittin. The amphipathic character of these peptides and their interactions with membranes resemble the properties of detergent molecules and analogies between membrane-active peptide and detergents are presented. Several models have been suggested to explain the pore-forming, membrane-lytic and antibiotic activities of these peptides. Here we suggest that these might be 'special cases' within complicated phase diagrams describing the morphological plasticity of peptide/lipid supramolecular assemblies.

  14. Cardiac protein expression patterns are associated with distinct inborn exercise capacity in non-selectively bred rats.

    Science.gov (United States)

    Ribeiro, L P; Freitas-Lima, L C; Naumann, G B; Meyrelles, S S; Lunz, W; Pires, S F; Andrade, H M; Carnielli, J B T; Figueiredo, S G

    2018-01-11

    In the present study, we successfully demonstrated for the first time the existence of cardiac proteomic differences between non-selectively bred rats with distinct intrinsic exercise capacities. A proteomic approach based on two-dimensional gel electrophoresis coupled to mass spectrometry was used to study the left ventricle (LV) tissue proteome of rats with distinct intrinsic exercise capacity. Low running performance (LRP) and high running performance (HRP) rats were categorized by a treadmill exercise test, according to distance run to exhaustion. The running capacity of HRPs was 3.5-fold greater than LRPs. Protein profiling revealed 29 differences between HRP and LRP rats (15 proteins were identified). We detected alterations in components involved in metabolism, antioxidant and stress response, microfibrillar and cytoskeletal proteins. Contractile proteins were upregulated in the LVs of HRP rats (α-myosin heavy chain-6, myosin light chain-1 and creatine kinase), whereas the LVs of LRP rats exhibited upregulation in proteins associated with stress response (aldehyde dehydrogenase 2, α-crystallin B chain and HSPβ-2). In addition, the cytoskeletal proteins desmin and α-actin were upregulated in LRPs. Taken together, our results suggest that the increased contractile protein levels in HRP rats partly accounted for their improved exercise capacity, and that proteins considered risk factors to the development of cardiovascular disease were expressed in higher amounts in LRP animals.

  15. Cardiac protein expression patterns are associated with distinct inborn exercise capacity in non-selectively bred rats

    Directory of Open Access Journals (Sweden)

    L.P. Ribeiro

    2018-01-01

    Full Text Available In the present study, we successfully demonstrated for the first time the existence of cardiac proteomic differences between non-selectively bred rats with distinct intrinsic exercise capacities. A proteomic approach based on two-dimensional gel electrophoresis coupled to mass spectrometry was used to study the left ventricle (LV tissue proteome of rats with distinct intrinsic exercise capacity. Low running performance (LRP and high running performance (HRP rats were categorized by a treadmill exercise test, according to distance run to exhaustion. The running capacity of HRPs was 3.5-fold greater than LRPs. Protein profiling revealed 29 differences between HRP and LRP rats (15 proteins were identified. We detected alterations in components involved in metabolism, antioxidant and stress response, microfibrillar and cytoskeletal proteins. Contractile proteins were upregulated in the LVs of HRP rats (α-myosin heavy chain-6, myosin light chain-1 and creatine kinase, whereas the LVs of LRP rats exhibited upregulation in proteins associated with stress response (aldehyde dehydrogenase 2, α-crystallin B chain and HSPβ-2. In addition, the cytoskeletal proteins desmin and α-actin were upregulated in LRPs. Taken together, our results suggest that the increased contractile protein levels in HRP rats partly accounted for their improved exercise capacity, and that proteins considered risk factors to the development of cardiovascular disease were expressed in higher amounts in LRP animals.

  16. Forward selection for multiple resistance across the non-selective glyphosate, glufosinate and oxyfluorfen herbicides in Lolium weed species.

    Science.gov (United States)

    Fernández, Pablo; Alcántara, Ricardo; Osuna, María D; Vila-Aiub, Martin M; Prado, Rafael De

    2017-05-01

    In the Mediterranean area, Lolium species have evolved resistance to glyphosate after decades of continual use without other alternative chemicals in perennial crops (olive, citrus and vineyards). In recent years, oxyfluorfen alone or mixed with glyphosate and glufosinate has been introduced as a chemical option to control dicot and grass weeds. Dose-response studies confirmed that three glyphosate-resistant Lolium weed species (L. rigidum, L. perenne, L. multiflorum) collected from perennial crops in the Iberian Peninsula have also evolved resistance to glufosinate and oxyfluorfen herbicides, despite their recent introduction. Based on the LD 50 resistance parameter, the resistance factor was similar among Lolium species and ranged from 14- to 21-fold and from ten- to 12-fold for oxyfluorfen and glufosinate respectively. Similarly, about 14-fold resistance to both oxyfluorfen and glufosinate was estimated on average for the three Lolium species when growth reduction (GR 50 ) was assessed. This study identified oxyfluorfen resistance in a grass species for the first time. A major threat to sustainability of perennial crops in the Iberian Peninsula is evident, as multiple resistance to non-selective glyphosate, glufosinate and oxyfluorfen herbicides has evolved in L. rigidum, L. perenne and L. multiflorum weeds. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  17. Peptides containing antigenic and cationic domains have enhanced, multivalent immunogenicity when bound to DNA vaccines.

    Science.gov (United States)

    Riedl, Petra; Reimann, Jörg; Schirmbeck, Reinhold

    2004-02-01

    We explored strategies to codeliver DNA- and peptide-based vaccines in a way that enhances the immunogenicity of both components of the combination vaccine for T cells. Specific CD8(+) T cell responses to an antigenic peptide are primed when the peptide is fused to a cationic peptide domain that is bound to plasmid DNA or oligonucleotides (ODN; with or without CpG motifs). Plasmid DNA mixed with antigenic/cationic peptides or histones forms large complexes with different biological properties depending on the molar ratios of peptide/protein and polynucleotide. Complexes containing high (but not low) molar ratios of cationic peptide to DNA facilitate transfection (DNA uptake and expression of the plasmid-encoded product) of cells. In contrast, complexes containing low (but not high) molar ratios of cationic peptide to DNA prime potent multispecific T cell responses after a single intramuscular injection of the complexes. The general validity of this observation was confirmed mixing different antigenic/cationic peptides with different DNA vaccines. In these vaccine formulations, multispecific CD8(+) T cell responses specific for epitopes of the peptide- as well as the DNA-based vaccine were efficiently coprimed, together with humoral antibody responses to conformational determinants of large viral antigens encoded by the DNA vaccine. The data indicate that mixtures of DNA vaccines with antigenic, cationic peptides are immunogenic vaccine formulations particularly suited for the induction of multispecific T cell responses.

  18. Treatment with non-selective beta blockers is associated with reduced severity of systemic inflammation and improved survival of patients with acute-on-chronic liver failure

    DEFF Research Database (Denmark)

    Mookerjee, Rajeshwar P; Pavesi, Marco; Thomsen, Karen Louise

    2016-01-01

    BACKGROUND & AIMS: Non-selective beta blockers (NSBBs) have been shown to have deleterious outcomes in patients with refractory ascites, alcoholic hepatitis and spontaneous bacterial peritonitis leading many physicians to stop the drug in these cases. Acute-on-chronic liver failure (ACLF) is char......BACKGROUND & AIMS: Non-selective beta blockers (NSBBs) have been shown to have deleterious outcomes in patients with refractory ascites, alcoholic hepatitis and spontaneous bacterial peritonitis leading many physicians to stop the drug in these cases. Acute-on-chronic liver failure (ACLF...

  19. ESI MS and PM5 semiempirical studies of gossypol schiff base with ( R)-tetrahydrofurfurylamine complexes and monovalent cations

    Science.gov (United States)

    Przybylski, Piotr; Włodarz, Magdalena; Schroeder, Grzegorz; Pankiewicz, Radosław; Brzezinski, Bogumil; Bartl, Franz

    2004-05-01

    Complexation of monovalent cations by a new Schiff base of gossypol with ( R)-tetrahydrofurfurylamine (GSTF) has been studied by ESI mass spectrometry as well as by PM5 semiempirical method. On the basis of ESI spectra it has been found that the new gossypol Schiff base forms only 1:1 complexes with all monovalent metal cations. With H + cation the Schiff base forms 1:1, 1:2 and 1:4 complexes. In the 1:1 and 1:2 complexes with protons, they are localised on the N atoms of the Schiff base. In the 1:4 complex two protons are localised on the N atoms and two other on the O atoms of the furan ring. In all complexes with protons the molecule exists in the imine-imine tautomeric form. The new Schiff base forms 1:1 complexes with monovalent cations, which occur in the enamine-enamine tautomeric form. The Li + and Na + cations in the complexes with GSTF are coordinated by oxygen atoms and N atoms of the Schiff base, whereas the K +, Rb + and Cs + cations are only coordinated by oxygen atoms. The structures of the complexes are calculated by PM5 semiempirical method and discussed.

  20. The mechanism of kaolin clay flocculation by a cation-independent bioflocculant produced by Chryseobacterium daeguense W6

    Directory of Open Access Journals (Sweden)

    Weijie Liu

    2015-03-01

    Full Text Available In recent years, several novel cation-independent bioflocculants have been reported, which can avoid the secondary contamination caused by addition of cations. However, compared with cation-dependent bioflocculants, the flocculating mechanism of cation-independent bioflocculants is largely unknown. In this study, a cation-independent bioflocculant MBF-W6 produced by Chryseobacterium daeguense W6 was used as a model to investigate the flocculating mechanism. The results showed that the major flocculating component of MBF-W6 is a complex of proteins and polysaccharides. The zeta potential results indicated that kaolin clay particles were not precipitated due to charge neutralization and the bridging mediated by cations did not play a major role in the flocculating process. These results are consistent with the fact that MBF-W6 is a cation-independent bioflocculant. Further scanning electron microscopic observation showed that MBF-W6 induced flocs formed tight packed structure, suggesting that the kaolin clay particles maybe directly attached and bridged by bioflocculant MBF-W6. In addition, we also found out that Fe3+ ions inhibit the flocculating activity of MBF-W6 by affecting –COO− and –NH groups. Therefore this study can improve our understanding on flocculating mechanism of cation-independent bioflocculants.

  1. The role of alkali metal cations in the stabilization of guanine quadruplexes: why K(+) is the best.

    Science.gov (United States)

    Zaccaria, F; Paragi, G; Fonseca Guerra, C

    2016-08-21

    The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li(+), Na(+), K(+), Rb(+), and Cs(+). The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity.

  2. Study of the chemical interactions of actinide cations in solution at macroscopic concentrations

    International Nuclear Information System (INIS)

    Maurice, C.

    1983-01-01

    The aim of this work was to study the interactions of pentavalent neptunium in dodecane-diluted tributyl phosphate with other metallic cations, especially uranium VI and ruthenium present in reprocessing solutions. Pentavalent neptunium on its own was shown to exist in several forms complexed by water and TBP and also to dimerise. In the complex it forms with uranium VI the interaction via the neptunyl oxygen is considerably enhanced in organic solution. Dibutyl phosphoric acid strengthens the interaction between neptunium and uranium. The Np V-ruthenium interaction reveals the existence of a new cation-cation complex; the process takes place in two successive stage and leads to the formation, reinforced and accelerated by HDBP, of a highly to the formation, reinforced and accelerated by HDBP, of a highly stable complex. These results contribute towards a better knowledge of the behaviour of neptunium in the reprocessing operation [fr

  3. Mechanism of bacterial inactivation by cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pavlova, I.B.; Samoylenko, I.I.

    1985-03-01

    The mechanism of bacteriocidal action of the cationic surfactant dimethylbenzylammonium chloride was studied on exposure of Staphylococcus aureus, Streptococcus faecium, Bacillus subtilis and Escherichia coli to different concentrations of the agent and determinations of survival plots. The data showed that the surfactant was bacteriocidal for all the bacteria tested at a concentration of 0.0001%, but more efficient in the case of the gram positives. Electron microscopy showed considerable damage and dissarrangement of the cytoplasmic membrane, indicating that the killing mechanism involved this organelle. It appears that cationic surfactants may constitute effective disinfectant preparations. 9 references, 2 figures.

  4. Non-selective regulation of peroxide and superoxide resistance genes by PerR in Campylobacter jejuni

    Directory of Open Access Journals (Sweden)

    Jong-Chul eKim

    2015-02-01

    Full Text Available Campylobacter jejuni is an important foodborne pathogen. The molecular mechanisms for the regulation of oxidative stress resistance have not yet been understood fully in this bacterium. In this study, we investigated how PerR (peroxide stress regulator modulates the transcriptional regulation of both peroxide and superoxide resistance genes in C. jejuni, particularly under oxidative stress conditions. The transcriptional levels of ahpC, katA, and sodB were substantially increased by aeration and oxidant exposure. Interestingly, a perR mutation completely abrogated the transcriptional response of ahpC, katA and sodB to oxidants. Furthermore, we demonstrated that perR transcription was reduced by aeration and oxidant exposure. In contrast to the unique role of PerR homologs in peroxide stress regulation in other bacteria, interestingly, C. jejuni PerR directly regulates the transcription of sodB, the most important gene in superoxide defense, as evidenced by the alteration of sodB transcription by the perR mutation and direct binding of rPerR to the sodB promoter. In addition, we also observed notable morphological changes in C. jejuni from spiral rods to coccoid morphology under aerobic conditions. Based on the intracellular ATP levels, C. jejuni entered a viable-but-non-culturable state under aerobic conditions. These findings clearly demonstrate that C. jejuni possesses a unique regulatory mechanism of oxidative stress defense that does not specifically distinguish between peroxide and superoxide defense, and PerR plays a pivotal role in this non-selective regulation of oxidative stress resistance in C. jejuni.

  5. Gas phase hydration of halogenated benzene cations. Is it hydrogen or halogen bonding?

    Science.gov (United States)

    Mason, Kyle A; Pearcy, Adam C; Attah, Isaac K; Platt, Sean P; Aziz, Saadullah G; El-Shall, M Samy

    2017-07-19

    Halogen bonding (XB) non-covalent interactions can be observed in compounds containing chlorine, bromine, or iodine which can form directed close contacts of the type R1-XY-R2, where the halogen X acts as a Lewis acid and Y can be any electron donor moiety including electron lone pairs on hetero atoms such as O and N, or π electrons in olefin double bonds and aromatic conjugated systems. In this work, we present the first evidence for the formation of ionic halogen bonds (IXBs) in the hydration of bromobenzene and iodobenzene radical cations in the gas phase. We present a combined thermochemical investigation using the mass-selected ion mobility (MSIM) technique and density functional theory (DFT) calculations of the stepwise hydration of the fluoro, chloro, bromo, and iodobenzene radical cations. The binding energy associated with the formation of an IXB in the hydration of the iodobenzene cation (11.2 kcal mol -1 ) is about 20% higher than the typical unconventional ionic hydrogen bond (IHB) of the CH δ+ OH 2 interaction. The formation of an IXB in the hydration of the iodobenzene cation involves a significant entropy loss (29 cal mol -1 K -1 ) resulting from the formation of a more ordered structure and a highly directional interaction between the oxygen lone pair of electrons of water and the electropositive region around the iodine atom of the iodobenzene cation. In comparison, the hydration of the fluorobenzene and chlorobenzene cations where IHBs are formed, -ΔS° = 18-21 cal mol -1 K -1 consistent with the formation of less ordered structures and loose interactions. The electrostatic potentials on the lowest energy structures of the hydrated halogenated benzene radical cations show clearly that the formation of an IXB is driven by a positively charged σ-hole on the external side of the halogen atom X along the C-X bond axis. The size of the σ-hole increases significantly in bromobenzene and iodobenzene radical cations which results in strong

  6. Cationic Tungsten(VI) Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    KAUST Repository

    Dey, Raju

    2016-04-13

    Tungsten-hexa-methyl readily reacts with B(C6F5)3 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  7. Cationic Tungsten(VI Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    Directory of Open Access Journals (Sweden)

    Dey Raju

    2016-03-01

    Full Text Available Tungsten-hexa-methyl readily reacts with B(C6F53 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  8. A cation-pi interaction in the binding site of the glycine receptor is mediated by a phenylalanine residue

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Millen, Kat S; Hanek, Ariele P

    2008-01-01

    Cys-loop receptor binding sites characteristically contain many aromatic amino acids. In nicotinic ACh and 5-HT3 receptors, a Trp residue forms a cation-pi interaction with the agonist, whereas in GABA(A) receptors, a Tyr performs this role. The glycine receptor binding site, however, contains...... of fluorinated Phe derivatives using unnatural amino acid mutagenesis. The data reveal a clear correlation between the glycine EC(50) value and the cation-pi binding ability of the fluorinated Phe derivatives at position 159, but not at positions 207 or 63, indicating a single cation-pi interaction between...

  9. Effect of cations on the hydrated proton.

    Science.gov (United States)

    Ottosson, Niklas; Hunger, Johannes; Bakker, Huib J

    2014-09-17

    We report on a strong nonadditive effect of protons and other cations on the structural dynamics of liquid water, which is revealed using dielectric relaxation spectroscopy in the frequency range of 1-50 GHz. For pure acid solutions, protons are known to have a strong structuring effect on water, leading to a pronounced decrease of the dielectric response. We observe that this structuring is reduced when protons are cosolvated with salts. This reduction is exclusively observed for combinations of protons with other ions; for all studied solutions of cosolvated salts, the effect on the structural dynamics of water is observed to be purely additive, even up to high concentrations. We derive an empirical model that quantitatively describes the nonadditive effect of cosolvated protons and cations. We argue that the effect can be explained from the special character of the proton in water and that Coulomb fields exerted by other cations, in particular doubly charged cations like Mg(2+)aq and Ca(2+)aq, induce a localization of the H(+)aq hydration structures.

  10. NMR studies of cation transport across membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

  11. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...

  12. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The

  13. Water Adsorption on Free Cobalt Cluster Cations

    NARCIS (Netherlands)

    Kiawi, Denis M.; Bakker, Joost M.; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L. B. F. M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+–H2O (n = 6–20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200–1700 cm–1 spectral range. All spectra exhibit a resonance close to the 1595 cm–1 frequency of the free

  14. Water adsorption on free cobalt cluster cations

    NARCIS (Netherlands)

    Kiawi, D.M.; Bakker, J.M.; Oomens, J.; Buma, W.J.; Jamshidi, Z.; Visscher, L.; Waters, L.B.F.M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+-​H2O (n = 6-​20) are produced through laser ablation and investigated via IR multiple photon dissocn. (IR-​MPD) spectroscopy in the 200-​1700 cm-​1 spectral range. All spectra exhibit a resonance close to the 1595 cm-​1 frequency of the free water

  15. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...

  16. Cationic flotation of some lithium ores

    International Nuclear Information System (INIS)

    Valadao, G.E.S.; Peres, A.E.C.; Silva, H.C. da

    1984-01-01

    The cationic flotation of some lithium ores (spodumene, amblygonite, petalite, lepidolite) is studied by the measure of zeta potential and micro-flotation tests in Hallimond tube. The effect of some modifier agents (corn starch, meta sodium silicate) on the lithium flotation is studied. (M.A.C.) [pt

  17. Behavior of cesium and thallium cations inside a calixarene cavity as probed by nuclear spin relaxation. Evidence of cation-pi interactions in water.

    Science.gov (United States)

    Cuc, Diana; Bouguet-Bonnet, Sabine; Morel-Desrosiers, Nicole; Morel, Jean-Pierre; Mutzenhardt, Pierre; Canet, Daniel

    2009-08-06

    We have studied the complexes formed between the p-sulfonatocalix[4]arene and cesium or thallium metal cation, first by carbon-13 longitudinal relaxation of the calixarene molecule at two values of the magnetic field B(0). From the longitudinal relaxation times of an aromatic carbon directly bonded to a proton, thus subjected essentially to the dipolar interaction with that proton, we could obtain the correlation time describing the reorientation of the CH bond. The rest of this study has demonstrated that it is also the correlation time describing the tumbling of the whole calixarene assembly. From three non-proton-bearing carbons of the aromatic cycles (thus subjected to the chemical shift anisotropy and dipolar mechanisms), we have been able to determine the variation of the chemical shift anisotropy when going from the free to the complex form of the calixarene. These variations not only provide the location of the cation inside the calixarene cavity but also constitute a direct experimental proof of the cation-pi interactions. These results are complemented by cesium and thallium relaxation measurements performed again at two values of the magnetic field B(0). An estimation of the mean distance between the cation and the calixarene protons could be obtained. These measurements have also revealed an important chemical shift anisotropy of thallium upon complexation.

  18. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  19. meso-Octamethylcalix[4]pyrrole as an effective macrocyclic receptor for the univalent thallium cation in the gas phase: Experimental and theoretical study

    Science.gov (United States)

    Polášek, Miroslav; Makrlík, Emanuel; Kvíčala, Jaroslav; Křížová, Věra; Vaňura, Petr

    2018-02-01

    By using electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent thallium cation (Tl+) forms with meso-octamethylcalix[4]pyrrole (1) the cationic complex species 1 Tl+. When this kinetically stable cation-π complex 1 Tl+ is collisionally activated, it decomposes by elimination of the whole ligand 1 or small meso-octamethylcalix[4]pyrrole fragments. Further, applying quantum chemical DFT calculations, four different conformations of the resulting complex 1 Tl+ were derived. It means that under the present experimental conditions, this ligand 1 can be considered as a very effective macrocyclic receptor for the thallium cation.

  20. A spectroscopic study of interaction of cationic dyes with heparin

    Directory of Open Access Journals (Sweden)

    R. Nandini

    2010-01-01

    Full Text Available The interaction of two cationic dyes namely, acridine orange and pinacyanol chloride with an anionic polyelectrolyte, heparin, has been investigated by spectrophotometric method.The polymer induced metachromasy in the dyes resulting in the shift of the absorption maxima of the dyes towards shorter wavelengths. The stability of the complexes formed between acridine orange and heparin was found to be lesser than that formed between pinacyanol chloride and heparin. This fact was further confirmed by reversal studies using alcohols, urea and surfactants. The interaction of acridine orange with heparin has also been investigated fluorimetrically.The interaction parameters revealed that binding between acridine orange and heparin arises due to electrostatic interaction while that between pinacyanol chloride and heparin is found to involve both electrostatic and hydrophobic forces. The effect of the structure of the dye in inducing metachromasy has also been discussed.

  1. Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals

    NARCIS (Netherlands)

    Gámez, F.; Hurtado, P.; Hortal, A.R.; Martínez-Haya, B.; Berden, G.; Oomens, J.

    2013-01-01

    The benchmark inclusion complexes formed by -cyclodextrin (CD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative CD-M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry,

  2. High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators

    Science.gov (United States)

    Janke, Christopher J.; Lopata, Vincent J.; Havens, Stephen J.; Dorsey, George F.; Moulton, Richard J.

    1999-01-01

    A mixture of epoxy resins such as a semi-solid triglycidyl ether of tris (hydroxyphenyl) methane and a low viscosity bisphenol A glycidyl ether and a cationic photoinitiator such as a diaryliodonium salt is cured by irradiating with a dosage of electron beams from about 50 to about 150 kGy, forming a cross-linked epoxy resin polymer.

  3. An oral delivery system for indomethicin engineered from cationic lipid emulsions and silica nanoparticles

    DEFF Research Database (Denmark)

    Simovic, Spomenka; Hui, He; Song, Yunmei

    2010-01-01

    We report on a porous silica-lipid hybrid microcapsule (SLH) oral delivery system for indomethacin fabricated from Pickering emulsion templates, where the drug forms an electrostatic complex with cationic lipid present in the oil phase. Dry SLH microcapsules prepared either by spray drying...

  4. Structures of the Dehydrogenation Products of Methane Activation by 5d Transition Metal Cations

    NARCIS (Netherlands)

    Lapoutre, V.J.F.; Redlich, B.; Meer, A.F.G.; Oomens, J.; Bakker, J.M.; Sweeney, A.; Mookherjee, A.; Armentrout, P.B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M+) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H](+) and H-2. However, the structure of the

  5. Structures of the dehydrogenation products of methane activation by 5d transition metal cations

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Redlich, B.; van der Meer, A. F. G.; Oomens, J.; Bakker, J. M.; Sweeney, A.; Mookherjee, A.; Armentrout, P. B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M +) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H]+ and H2. However, the structure of the dehydrogenation

  6. Saliva cations composition in humans with the disorders of gastrointestinal tract activity

    Directory of Open Access Journals (Sweden)

    M. V. Markina

    2010-02-01

    Full Text Available Connection between the pathologies of alimentary canal and the changes of concentrations of microelements in human saliva is under consideration. The decrease of the cations content in saliva under forming and developing the pathological process in gastrointestinal tract is shown.

  7. Emission spectra of the cations of 1,3- and 1,4-dibromotetrafluorobenzene and of 1,3,5-tribromotrifluorobenzene in the gaseous phase

    Science.gov (United States)

    Maier, John Paul; Marthaler, O.; Mohraz, Manijeh; Shiley, R.H.

    1980-01-01

    A search was made for radiative decay of electronically excited cations of 24 bromobenzenes and of their fluoro-substituted derivatives in the gaseous phase. The only emission spectra detected were for the cations of 1,3- and 1,4-dibromotetrafluorobenzene and of 1,3,5-tribromotrifluorobenzene. The band systems, which are found between 670 and 830 nm, are assigned to the B(??-1) ??? A(??-1), X(??-1) electronic transitions of these cations. The assignments are based on the Ne(I) photoelectron spectra which are also presented for some of the studied species. The interpretation for the absence of detectable emission is that the nature of the B cationic states is ??-1, except in the case of 1,3- and 1,4-dibromobenzene cations for which B states are still formed by ??-1 processes. Possible reasons for these observations are discussed. The symmetries of the lowest three electronic states of the studied cations are given. ?? 1980.

  8. Does the cyclohexyl cation exist in the dilute gas state. Direct evidence from a radiolytic study

    International Nuclear Information System (INIS)

    Attina, M.; Cacace, F.; Giacomello, P.

    1981-01-01

    The isomeric composition of the gaseous C 6 H 11 + cations obtained via hydride ion abstraction from c-C 6 H 12 has been investigated by allowing the charged species to react in the gas phase with water and analyzing the neutral products formed. The nature and the yields of the major products, cyclohexanol, cyclohexanone, and 1-methylcyclopentanol, and their dependence on the pressure and the composition of the gaseous system provide direct evidence for the existence of the cyclohexyl cation in the dilute gas state, with a lifetime in excess of 10 -7 s, and confirm its facile rearrangement to the more stable 1-methylcyclopentyl ion

  9. Radiation-induced polymerisation of 2,3-dihydrofuran: free-radical or cationic mechanism?

    Science.gov (United States)

    Janovský, Igor; Naumov, Sergej; Knolle, Wolfgang; Mehnert, Reiner

    2005-02-01

    Concentrated (10 mol%) solutions of 2,3-dihydrofuran in CFCl 2CF 2Cl matrix were irradiated at 77 K and several intermediates (dimer radical cation, dihydrofuryl radical, and polymer radicals) were observed by low-temperature EPR spectroscopy. The irradiated solutions yielded after melting a polymeric product, which was characterised by IR spectroscopy and gel permeation chromatography. The polydisperse polymer is assumed to be formed mainly by a cationic process initiated by a dimer carbocation. The free-radical mechanism via the dihydrofuryl radical leads to low molecular weight oligomers only. Quantum chemical calculations support the interpretation of the experimental results.

  10. First-Principles Modeling of ThO2 Solid Solutions with Oxides of Trivalent Cations

    Science.gov (United States)

    Alexandrov, Vitaly; Asta, Mark; Gronbech-Jensen, Niels

    2010-03-01

    Solid solutions formed by doping ThO2 with oxides of trivalent cations, such as Y2O3 and La2O3, are suitable for solid electrolyte applications, similar to doped zirconia and ceria. ThO2 has also been gaining much attention as an alternative to UO2 in nuclear energy applications, the aforementioned trivalent cations being important fission products. In both cases the mixing energetics and short-range ordering/clustering are key to understanding structural and transport properties. Using first-principles atomistic calculations, we address intra- and intersublattice interactions for both cation and anion sublattices in ThO2-based fluorite-type solid solutions and compare the results with similar modeling studies for related trivalent-doped zirconia systems.

  11. THEORETICAL STUDY ON 15-CROWN-5 COMPLEX WITH SOME METAL CATIONS

    Directory of Open Access Journals (Sweden)

    Yahmin Yahmin

    2012-06-01

    Full Text Available The capability of 15-crown-5 ethers to form complexes with some metal cations (Li+, Na+, K+, Zn2+, Cd2+ and Hg2+ was investigated by an ab initio quantum mechanical method. The calculations were performed at the RHF/lanl2mb level of theory. The interaction energies were used to evaluate the metal binding capability of the crown ether. The effect of nature of the metal on the binding properties was also studied. The results of the calculations showed that the interaction energy of the complexes increased in proportion with the ratio of ion charge, electronegativity and ionization potential to the cation diameter. In addition, based on the extraction distribution coefficient in the gas phase, it is found that the 15-crown-5 could not extract metal cations investigated.

  12. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  13. PEMFC contamination model: Foreign cation exchange with ionomer protons

    Science.gov (United States)

    St-Pierre, Jean

    2011-08-01

    A generic, transient fuel cell ohmic loss mathematical model was developed for the case of contaminants that ion exchange with ionomer protons. The model was derived using step changes in contaminant concentration, constant operating conditions and foreign cation transport via liquid water droplets. In addition, the effect of ionomer cations redistribution within the ionomer on thermodynamic, kinetic and mass transport losses and migration were neglected. Thus, a simpler, ideal, ohmic loss case is defined and is applicable to uncharged contaminant species and gas phase contaminants. The closed form solutions were validated using contamination data from a membrane exposed to NH3. The model needs to be validated against contamination and recovery data sets including an NH4+ contaminated membrane exposed to a water stream. A method is proposed to determine model parameters and relies on the prior knowledge of the initial ionomer resistivity. The model expands the number of previously derived cases. Most models in this inventory, derived with the assumption that the reactant is absent, lead to different dimensionless current vs. time behaviors similar to a fingerprint. These model characteristics facilitate contaminant mechanism identification. Separation between membrane and catalyst (electroinactive contaminant) contamination is conceivably possible using additional indicative cell resistance measurements. Contamination is predicted to be significantly more severe under low relative humidity conditions.

  14. Ion-pair reversed phase liquid chromatography with ultraviolet detection for analysis of ultraviolet transparent cations.

    Science.gov (United States)

    He, Yan; Cook, Kenneth S; Littlepage, Eric; Cundy, John; Mangalathillam, Ratish; Jones, Michael T

    2015-08-21

    This paper describes the use of an anionic ion-pair reagent (IPR) to impove the ultraviolet (UV) detection and hydrophobic retention of polar and UV transparent cations. Anionic IPR added to the mobile phase forms an ion-pair with cations. Formation of the ion-pair causes a redshift in the absorption wavength, making it possible for direct UV detection of UV-inactive cations. The ion-pairs with increased hydrophobicity were separated by reversed phase liquid chromatography (RPLC). Different perfluorinated caboxylic acids (trifluoroacetic acid, heptafluorobutyric acid, nonafluoropentanoic acid) were evaluted as IPR in the separation and detection of the common cations sodium, ammonium and Tris(hydroxymethyl)aminomethane (Tris). The effects of the IPR type and concentration on separation and detection have been investigated to understand the separation and detection mechanisms. The optimal separation and detection condtions were attained with mobile phase containing 0.1% nonafluoropentanoic acid and with the UV detection at 210nm. UV detection and charged aerosol detection (CAD) were compared in the quantitation of the cations. The limit of quantitation (LOQ) of sodium and Tris with UV detection is comparable to that by CAD. The LOQ of ammonium with UV detection (1ppm or 3ng) is about 20-fold lower than that (20ppm or 60ng) by CAD. The RPLC-UV method was used to monitor ammonium clearance during ultrafiltration and diafiltration in the manfucaturing of biopharmceutical drug substance. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants.

    Science.gov (United States)

    Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin

    2016-02-17

    This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.

  16. Synthesis, characterization and transfection activity of new saturated and unsaturated cationic lipids.

    Science.gov (United States)

    Arpicco, Silvia; Canevari, Silvana; Ceruti, Maurizio; Galmozzi, Enrico; Rocco, Flavio; Cattel, Luigi

    2004-11-01

    We synthesized new cationic lipids, analogue to N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethylammonium bromide (DMRIE), in order to compare those containing a dodecyl chain with those having a relatively long chain with two or five double bonds, such as squalenyl and dihydrofarnesyl derivatives, or complex saturated structures, such as squalane derivatives. The fusogenic helper lipid dioleoylphosphatidylethanolamine (DOPE) was added to cationic lipids to form a stable complex. Liposomes composed of 50:50 w/w cationic lipid/DOPE were prepared and incubated with plasmidic DNA at various charge ratios and the diameter and zeta potential of the complexes were measured. The surface charge of the DNA/lipid complexes can be controlled by adjusting the cationic lipid/DNA ratio. Finally, we tested the in vitro transfection efficiency of the cationic lipid/DNA complexes using different cell lines. The transfection efficiency was highest for the dodecyloxy derivative containing a single hydroxyethyl group in the head, followed by the dodecyloxy and the farnesyloxy trimethylammonium derivatives. Instead the C27 squalenyl and C27 squalanyl derivatives resulted inactive.

  17. Glutathione radical cation in the gas phase; generation, structure and fragmentation.

    Science.gov (United States)

    Zhao, Junfang; Siu, K W Michael; Hopkinson, Alan C

    2011-11-07

    Two different chemical methods have been used to form glutathione radical cations: (1) collision-induced dissociations (CIDs) of the ternary complex [Cu(II)(tpy)(M)]˙(2+) (M = GSH, tpy = 2,2':6',2''-terpyridine) and (2) homolysis of the S-NO bond in protonated S-nitrosoglutathione. The radical cations, M˙(+), were trapped and additional CIDs were performed. They gave virtually identical CID spectra, suggesting a facile interconversion between initial structures prior to fragmentation. DFT calculations at the B3LYP/6-31++G(d,p) level of theory have been used to study interconversion between different isomers of the glutathione radical cation and to examine mechanisms by which these ions fragment. The N-terminal α-carbon-centred radical cation, strongly stabilized by the captodative effect, is at the global minimum, which is 8.5 kcal mol(-1) lower in enthalpy than the lowest energy conformer of the S-centred radical cation. The barrier against interconversion is 18.1 kcal mol(-1) above the S-centred radical.

  18. Solvation Effect on Complexation of Alkali Metal Cations by a Calix[4]arene Ketone Derivative.

    Science.gov (United States)

    Požar, Josip; Nikšić-Franjić, Ivana; Cvetnić, Marija; Leko, Katarina; Cindro, Nikola; Pičuljan, Katarina; Borilović, Ivana; Frkanec, Leo; Tomišić, Vladislav

    2017-09-14

    The medium effect on the complexation of alkali metal cations with a calix[4]arene ketone derivative (L) was systematically examined in methanol, ethanol, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile. In all solvents the binding of Na + cation by L was rather efficient, whereas the complexation of other alkali metal cations was observed only in methanol and acetonitrile. Complexation reactions were enthalpically controlled, while ligand dissolution was endothermic in all cases. A notable influence of the solvent on NaL + complex stability could be mainly attributed to the differences in complexation entropies. The higher NaL + stability in comparison to complexes with other alkali metal cations in acetonitrile was predominantly due to a more favorable complexation enthalpy. The 1 H NMR investigations revealed a relatively low affinity of the calixarene sodium complex for inclusion of the solvent molecule in the calixarene hydrophobic cavity, with the exception of acetonitrile. Differences in complex stabilities in the explored solvents, apart from N,N-dimethylformamide and acetonitrile, could be mostly explained by taking into account solely the cation and complex solvation. A considerable solvent effect on the complexation equilibria was proven to be due to an interesting interplay between the transfer enthalpies and entropies of the reactants and the complexes formed.

  19. Enhanced tumor localization and retention of chlorin e6 in cationic nanolipoplexes potentiate the tumor ablation effects of photodynamic therapy

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Gayong; Lee, Sangbin; Kim, Chan-Wha [School of Life Sciences and Biotechnology, Korea University, Seoul (Korea, Republic of); Kim, Young Bong [Department of Animal Biotechnology, Konkuk University, Seoul (Korea, Republic of); Oh, Yu-Kyoung, E-mail: ohyk@snu.ac.kr [College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul (Korea, Republic of)

    2011-09-07

    Here we report the tumor ablation effects of the negatively charged photosensitizer chlorin e6 (Ce6) in nanocomplexes. Ce6 was complexed to cationic 1,2-dioleoyl-sn-glycero-3-ethylphosphocholine-based liposomes, forming cationic nanolipoplexes. The loading efficiency of Ce6 to cationic nanolipoplexes was greater than 90%. The degree of enhancement of cellular uptake of Ce6 by treatment in cationic nanolipoplexes increased with the concentration of Ce6, showing 18.3-fold higher uptake than free Ce6 at 15 {mu}M. Molecular imaging revealed the preferential distribution and retention of Ce6 in SCC7 tumor tissues after intravenous administration of Ce6 in cationic nanolipoplexes. Moreover, localized illumination of mice receiving Ce6 in cationic nanolipoplexes resulted in the formation of thick scabs over tumor regions, and complete ablation of tumors after scab detachment. In contrast, continuous growth of tumors was observed in the group treated with free Ce6. Our results suggest that the cationic nanolipoplexes of Ce6 improve the therapeutic effects of photodynamic cancer therapy as compared to free Ce6.

  20. Multi-signalling cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline based hetarylazo dye

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Paramjit, E-mail: paramjit19in@yahoo.co.in [Department of Chemistry, UGC-Centre of Advance Studies-I, UGC SAP (DRS-I) Department, Guru Nanak Dev University, Amritsar 143 005 (India); Sareen, Divya [Department of Chemistry, UGC-Centre of Advance Studies-I, UGC SAP (DRS-I) Department, Guru Nanak Dev University, Amritsar 143 005 (India); Kaur, Mandeep [Department of Chemistry, UGC-Centre of Advance Studies-I, UGC SAP (DRS-I) Department, Guru Nanak Dev University, Amritsar 143 005 (India); Organic Synthesis Laboratory, Department of Applied Chemical Sciences and Technology, UGC SAP (DRS-I) Department, Guru Nanak Dev University, Amritsar 143 005 (India); Singh, Kamaljit, E-mail: kamaljit19in@yahoo.co.in [Organic Synthesis Laboratory, Department of Applied Chemical Sciences and Technology, UGC SAP (DRS-I) Department, Guru Nanak Dev University, Amritsar 143 005 (India)

    2013-05-17

    Graphical abstract: The chromogenic and electrochemical behaviour of bis(pyridine-2-yl methyl)aniline based hetarylazo dye gets perturbed in the presence of cations, most effective being Cu{sup 2+}. The conversion of ICT to ICT/MLCT is witnessed by TD-DFT calculations. -- Highlights: •Cation sensing of hetarylazo dye based upon visual, absorption and electrochemical changes is described. •Sensing mechanism is based upon perturbation in intramolecular charge-transfer upon interaction with cations. •Sensing protocol is supported by {sup 1}H NMR studies as well as theoretical calculations. •Hetarylazo dye acts as a multichannel sensor. •Response of the dye towards various cations has also been explored in acidic pH window. -- Abstract: We investigated the cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline appended hetarylazo dye via chromogenic and electrochemical transduction channels. The binding pocket constituting both the pyridyl as well as aniline nitrogen atoms acts as recognition site for the cations and consequent perturbation in the intramolecular charge-transfer prevailing in the dye results in the chromogenic response manifested in the form of hypsochromic shift in the intramolecular charge-transfer band and the attendant naked-eye color changes. The dye exhibits significant changes in its electrochemical behaviour in the presence of cations. The experimental results are also rationalized by time-dependent density functional theory (TD-DFT) calculations.

  1. The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes

    DEFF Research Database (Denmark)

    Korsholm, Karen Smith; Agger, Else Marie; Foged, Camilla

    2007-01-01

    Cationic liposomes are being used increasingly as efficient adjuvants for subunit vaccines but their precise mechanism of action is still unknown. Here, we investigated the adjuvant mechanism of cationic liposomes based on the synthetic amphiphile dimethyldioctadecylammonium (DDA). The liposomes...... concentrations. This efficient adsorption onto the liposomes led to an enhanced uptake of OVA by BM-DCs as assessed by flow cytometry and confocal fluorescence laser-scanning microscopy. This was an active process, which was arrested at 4 degrees and by an inhibitor of actin-dependent endocytosis, cytochalasin D....... In vivo studies confirmed the observed effect because adsorption of OVA onto DDA liposomes enhanced the uptake of the antigen by peritoneal exudate cells after intraperitoneal injection. The liposomes targeted antigen preferentially to antigen-presenting cells because we only observed a minimal uptake...

  2. Regulation of Cation Balance in Saccharomyces cerevisiae

    Science.gov (United States)

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  3. Mechanism of metal cationization in organic SIMS

    International Nuclear Information System (INIS)

    Wojciechowski, I.; Delcorte, A.; Gonze, X.; Bertrand, P.

    2003-01-01

    A scenario of metal cationization in which the organic molecule combines with a neutral excited metal atom is proposed. Ionization of the nascent complex occurs via ejection of an electron during the association process. Electron structure calculations for the model systems C 6 H 6 +Me (Me=Ag, Cu, Au) using the density functional theory give a strong argument in favor of the proposed mechanism

  4. Proton dynamics investigation for dimethyl ammonium cation

    International Nuclear Information System (INIS)

    Pislewski, N.; Tritt-Goc, J.; Jakubas, R.

    1995-01-01

    Proton dynamics in dimethyl ammonium cation has been investigated by means of NMR and spin echo methods in polycrystalline salts [NH 2 (CH 3 ) 2 ] + Bi 2 J 9 - and [NH 2 (CH 3 ) 2 ] + SbJ 9 - . Spin-lattice relaxation time as well as second moment of NMR line have been measured for influence study of crystal structure changes on proton dynamics

  5. Late airway obstruction and neutrophil infiltration in sensitized mice after antigen provocation were suppressed by selective and non-selective phosphodiesterase inhibitors

    Directory of Open Access Journals (Sweden)

    Osamu Kaminuma

    1997-01-01

    Full Text Available Suppression of antigen-induced late airway obstruction associated with neutrophilic inflammation by selective and non-selective phosphodiesterase (PDE inhibitors was investigated in mice. Respiratory resistance (Rrs increased in sensitized BDF1 mice 4-6 h after antigen provocation, whereas no obvious immediate reaction was observed. This reaction was associated with marked airway neutrophilia without significant infiltration of eosinophils. A selective PDE IV inhibitor, T-440 (10-30 mg/kg, and a non-selective PDE inhibitor, theophylline (10 mg/kg, significantly inhibited airway obstruction and neutrophilia when administered orally. An anti-allergic drug, ketotifen (1 mg/kg, caused slight inhibition of airway obstruction, whereas it did not affect airway neutrophilia. These results suggest that neutrophilic inflammation plays a role in the airway obstructive reaction and that PDE has a regulatory role in obstructive airway disease associated with airway inflammation.

  6. Comparative analysis of cation/proton antiporter superfamily in plants

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Chuyu [ORNL; Yang, Xiaohan [ORNL; Xia, Xinli [Beijing Forestry University, China; Yin, Weilun [Beijing Forestry University, China

    2013-01-01

    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant specieswas reported.We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240members are separated into three families, i.e., Na+/H+ exchangers, K+ efflux antiporters, and cation/H+ exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H+ exchangers in the examined angiospermspecies. Sliding windowanalysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and foundmostmotifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants.

  7. Use of grape seed and its natural polyphenol extracts as a natural organic coagulant for removal of cationic dyes.

    Science.gov (United States)

    Jeon, Jong-Rok; Kim, Eun-Ju; Kim, Young-Mo; Murugesan, Kumarasamy; Kim, Jae-Hwan; Chang, Yoon-Seok

    2009-11-01

    Natural organic coagulants (NOCs) such as chitosan and Moringa oleifera seeds have been extensively characterized for potential application in water treatment as an alternative to metal-based coagulants. However, the action of both chitosan and M. oleifera seeds is mainly restricted to anionic organic pollutants because of their cationic functional groups affording poor cationic pollutant coagulation by electrostatic repulsion. In this study, we employed ethanolic grape seed extract (GSE) and grape seed-derived polyphenols such as tannic acid and catechin in an effort to find novel NOCs showing stable anionic forms for removal of cationic organic pollutants. The target substances tested were malachite green (MG) and crystal violet (CV), both mutagenic cationic dyes. Polyphenol treatment induced fast decolorization followed by gradual floc formation concomitant with red or blue shifts in maximum absorbance wavelengths of the cationic dyes. Liquid chromatography analysis of flocs formed by polyphenols directly showed that initial supramolecular complexes attributed mainly to electrostatic attraction between polyphenol hydroxyphenyl groups and cationic dyes further progressed into stronger aggregates, leading to precipitation of dye-polyphenol complexes. Consistent with the results obtained using catechin and tannic acid, use of GSE also resulted in effective decolorization and coagulation of soluble MG and CV in aqueous solutions. Screening of several organic GSE components for NOC activity strongly suggested that natural polyphenols are the main organic ingredients causing MG and CV removal via gradual floc formation. The treatment by natural polyphenols and GSE decreased toxicity of MG- or CV-contaminated water.

  8. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Science.gov (United States)

    Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

    2013-08-13

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  9. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C.; Larese, Kathleen Caroline; Bontchev, Ranko Panayotov

    2017-05-30

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  10. Trivalent Cation Induced Bundle Formation of Filamentous fd Phages.

    Science.gov (United States)

    Korkmaz Zirpel, Nuriye; Park, Eun Jin

    2015-09-01

    Bacteriophages are filamentous polyelectrolyte viral rods infecting only bacteria. In this study, we investigate the bundle formation of fd phages with trivalent cations having different ionic radii (Al(3+) , La(3+) and Y(3+) ) at various phage and counterion concentrations, and at varying bundling times. Aggregated phage bundles were detected at relatively low trivalent counterion concentrations (1 mM). Although 10 mM and 100 mM Y(3+) and La(3+) treatments formed larger and more intertwined phage bundles, Al(3+) and Fe(3+) treatments lead to the formation of networking filaments. Energy dispersive X-ray spectroscopy (EDX) analyses confirmed the presence of C, N and O peaks on densely packed phage bundles. Immunofluorescence labelling and ELISA analyses with anti-p8 antibodies showed the presence of phage filaments after bundling. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The adsorption of helium atoms on small cationic gold clusters.

    Science.gov (United States)

    Goulart, Marcelo; Gatchell, Michael; Kranabetter, Lorenz; Kuhn, Martin; Martini, Paul; Gitzl, Norbert; Rainer, Manuel; Postler, Johannes; Scheier, Paul; Ellis, Andrew M

    2018-04-04

    Adducts formed between small gold cluster cations and helium atoms are reported for the first time. These binary ions, Aun+Hem, were produced by electron ionization of helium nanodroplets doped with neutral gold clusters and were detected using mass spectrometry. For a given value of n, the distribution of ions as a function of the number of added helium atoms, m, has been recorded. Peaks with anomalously high intensities, corresponding to so-called magic number ions, are identified and interpreted in terms of the geometric structures of the underlying Aun+ ions. These features can be accounted for by planar structures for Aun+ ions with n ≤ 7, with the addition of helium having no significant effect on the structures of the underlying gold cluster ions. According to ion mobility studies and some theoretical predictions, a 3-D structure is expected for Au8+. However, the findings for Au8+ in this work are more consistent with a planar structure.

  12. Fabrication of cationic chitin nanofiber/alginate composite materials.

    Science.gov (United States)

    Sato, Koki; Tanaka, Kohei; Takata, Yusei; Yamamoto, Kazuya; Kadokawa, Jun-Ichi

    2016-10-01

    We have already found that an amidinated chitin, which was prepared by the reaction of a partially deacetylated chitin with N,N-dimethylacetamide dimethyl acetal, was converted into an amidinium chitin bicarbonate with nanofiber morphology by CO2 gas bubbling and ultrasonic treatments in water. In this study, we performed the fabrication of composite materials of such cationic chitin nanofibers with an anionic polysaccharide, sodium alginate, by ion exchange. When the amidinium chitin bicarbonate nanofiber aqueous dispersion was added to an aqueous solution of sodium alginate, the composite material was agglomerated, which was isolated by centrifugation, filtration, and lyophilization, to form a manipulatable sheet. The morphology of the resulting sheet at nano-scale was evaluated by SEM measurement. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Separation of certain carboxylic acids utilizing cation exchange membranes

    Science.gov (United States)

    Chum, Helena L.; Sopher, David W.

    1984-01-01

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  14. Cationic niosomes an effective gene carrier composed of novel spermine-derivative cationic lipids: effect of central core structures.

    Science.gov (United States)

    Opanasopit, Praneet; Leksantikul, Lalita; Niyomtham, Nattisa; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Yingyongnarongkul, Boon-Ek

    2017-05-01

    Cationic niosomes formulated from Span 20, cholesterol (Chol) and novel spermine-based cationic lipids of multiple central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) were successfully prepared for improving transfection efficiency in vitro. The niosomes composed of spermine cationic lipid with central core structure of di(oxyethyl)amino revealed the highest gene transfection efficiency. To investigate the factors affecting gene transfection and cell viability including differences in the central core structures of cationic lipids, the composition of vesicles, molar ratio of cationic lipids in formulations and the weight ratio of niosomes to DNA. Cationic niosomes composed of nonionic surfactants (Span20), cholesterol and spermine-based cationic lipids of multiple central core structures were formulated. Gene transfection and cell viability were evaluated on a human cervical carcinoma cell line (HeLa cells) using pDNA encoding green fluorescent protein (pEGFP-C2). The morphology, size and charge were also characterized. High transfection efficiency was obtained from cationic niosomes composed of Span20:Chol:cationic lipid at the molar ratio of 2.5:2.5:0.5 mM. Cationic lipids with di(oxyethyl)amino as a central core structure exhibited highest transfection efficiency. In addition, there was also no serum effect on transfection efficiency. These novel cationic niosomes may constitute a good alternative carrier for gene transfection.

  15. Interactions of cationic trimeric, gemini and monomeric surfactants with trianionic curcumin in aqueous solution.

    Science.gov (United States)

    Wang, Meina; Wu, Chunxian; Tang, Yongqiang; Fan, Yaxun; Han, Yuchun; Wang, Yilin

    2014-05-21

    Interactions of trianionic curcumin (Cur(3-)) with a series of cationic surfactants, monomeric surfactant dodecyl trimethylammonium bromide (DTAB), dimeric surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and trimeric surfactant tri(dodecyldimethylammonioacetoxy)diethyltriamine trichloride (DTAD), have been investigated in aqueous solution of pH 13.0. Surface tension and spectral measurements indicate that the cationic surfactants display a similar surfactant concentration dependent interaction process with Cur(3-), involving three interaction stages. At first the three cationic surfactants electrostatically bind on Cur(3-) to form the surfactant-Cur(3-) complex. Then the bound and unbound cationic surfactants with Cur(3-) aggregate into surfactant-Cur(3-) mixed micelles through hydrophobic interactions above the critical micelle concentration of the surfactants (CMCC) in the presence of Cur(3-). Finally excess unbound surfactants self-assemble into micelles like those without Cur(3-). For all the three surfactants, the addition of Cur(3-) only decreases the critical micelle concentration of 12-6-12 but does not affect the critical micelle concentration of DTAB and DTAD. As the oligomeric degree of surfactants increases, the intermolecular interaction of the cationic surfactants with Cur(3-) increases and the surfactant amount needed for Cur(3-) encapsulation decreases. Compared with 12-6-12, either the weaker interaction of DTAB with Cur(3-) or stronger interaction of DTAD with Cur(3-) limits the stability or solubility of Cur(3-) in surfactant micelles. Therefore, gemini surfactant 12-6-12 is the best choice to effectively suppress Cur(3-) degradation at very low concentrations. Isothermal titration microcalorimetry, surface tension and (1)H NMR results reveal that 12-6-12 and Cur(3-) form a (12-6-12)2-Cur(3-) complex and start to form micelles at extremely decreased concentrations, where either 12-6-12 or Cur(3-) works as a bridge

  16. Modular forms

    NARCIS (Netherlands)

    Edixhoven, B.; van der Geer, G.; Moonen, B.; Edixhoven, B.; van der Geer, G.; Moonen, B.

    2008-01-01

    Modular forms are functions with an enormous amount of symmetry that play a central role in number theory, connecting it with analysis and geometry. They have played a prominent role in mathematics since the 19th century and their study continues to flourish today. Modular forms formed the

  17. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  18. Complexes of natural carbohydrates with metal cations

    International Nuclear Information System (INIS)

    Alekseev, Yurii E; Garnovskii, Alexander D; Zhdanov, Yu A

    1998-01-01

    Data on the interaction of natural carbohydrates (mono-, oligo-, and poly-saccharides, amino sugars, and natural organic acids of carbohydrate origin) with metal cations are surveyed and described systematically. The structural diversity of carbohydrate metal complexes, caused by some specific features of carbohydrates as ligands, is demonstrated. The influence of complex formation on the chemical properties of carbohydrates is discussed. It is shown that the formation of metal complexes plays an important role in the configurational and conformational analysis of carbohydrates. The practical significance of the coordination interaction in the series of carbohydrate ligands is demonstrated. The bibliography includes 571 references.

  19. Homogeneous cation exchange membrane by radiation grafting

    International Nuclear Information System (INIS)

    Kolhe, Shailesh M.; G, Agathian; Ashok Kumar

    2001-01-01

    Preparation of a strong cation exchange membrane by radiation grafting of styrene on to polyethylene (LDPE) film by mutual irradiation technique in the presence of air followed by sulfonation is described. The grafting has been carried out in the presence of air and without any additive. Low dose rate has been seen to facilitate the grafting. Further higher the grafting percentage more is the exchange capacity. The addition of a swelling agent during the sulfonation helped in achieving the high exchange capacity. The TGA-MASS analysis confirmed the grafting and the sulfonation. (author)

  20. Short- and medium-range structural order around cations in glasses: amultidisciplinary approachOrdre local à courte et moyenne distance autour des cations dans les verres: une approche pluridisciplinaire

    Science.gov (United States)

    Cormier, Laurent; Galoisy, Laurence; Delaye, Jean-Marc; Ghaleb, Dominique; Calas, Georges

    2001-03-01

    The structural environment of cations at a short- and medium-range scale may be investigated either by spectroscopic methods or by radiation diffraction giving either a description of the geometry and symmetry of the cationic site, including the nature of the chemical bond, or a chemically resolved radial distribution function. Cations exhibit several original structural properties in oxide glasses. Short-range order is characterized by unusual coordination numbers, such as five-coordinated sites or tetrahedral sites which are in a network forming position, with the relative proportion of these sites depending on glass composition. Oxide glasses can also exhibit elements with unusual oxidation states, such as pentavalent uranium. The determination of the sites occupied by the elements in their different oxidation states allows to rationalize the chemical dependence of redox equilibria, which is the way to predict Fe behavior in magmatic silicate systems. Several experimental data lend support that cations are located in domains extending up to more than 8 Å radius, in which cationic polyhedra may be linked together either by edges or by corners. In low alkali borate glasses, transition elements such as Co, Ni, Zn exist in peculiar highly ordered domains corresponding to the presence of rigid borate units. Strong differences are observed between modifying and charge compensating cations, either concerning site geometry or medium-range organization. The use of numerical models for experimental data inversion allows to rationalize the structural behavior of the various glass components.

  1. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    Science.gov (United States)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities.

  2. Cationic Antimicrobial Polymers and Their Assemblies

    Science.gov (United States)

    Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

    2013-01-01

    Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

  3. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

    Nava Galve, R.G.

    1993-01-01

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  4. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  5. [Cost-effectiveness analysis of celecoxib versus non-selective non-steroidal anti-inflammatory drug therapy for the treatment of osteoarthritis in Spain: A current perspective].

    Science.gov (United States)

    De Lossada, A; Oteo-Álvaro, Á; Giménez, S; Oyagüez, I; Rejas, J

    2016-01-01

    To assess the cost-effectiveness of celecoxib and non-selective non-steroidal anti-inflammatory drugs for the treatment of osteoarthritis in clinical practice in Spain. A decision-tree model using distribution, doses, treatment duration and incidence of GI and CV events observed in the pragmatic PROBE-designed «GI-Reasons» trial was used for cost-effectiveness. Effectiveness was expressed in terms of event averted and quality-adjusted life-years (QALY) gained. QALY were calculated based on utility decrement in case of any adverse events reported in GI-Reasons trial. The National Health System perspective in Spain was applied; cost calculations included current prices of drugs plus cost of adverse events occurred. The analysis was expressed as an incremental cost-effectiveness ratio per QALY gained and per event averted. One-way and probabilistic analyses were performed. Compared with non-selective non-steroidal anti-inflammatory drugs, at current prices, celecoxib treatment had higher overall treatment costs €201 and €157, respectively. However, celecoxib was associated with a slight increase in QALY gain and significantly lower incidence of gastrointestinal events (p<.001), with mean incremental cost-effectiveness ratio of €13,286 per QALY gained and €4,471 per event averted. Sensitivity analyses were robust, and confirmed the results of the base case. Celecoxib at current price may be considered as a cost-effective alternative vs. non-selective non-steroidal anti-inflammatory drugs in the treatment of osteoarthritis in daily practice in the Spanish NHS. Copyright © 2015 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Synthesis of conformation switchable cationic polypeptides based on poly(S-propargyl-cysteine) for use as siRNA delivery.

    Science.gov (United States)

    Yi, Ling; Wang, Yisi; Lin, Guanliang; Lin, Danling; Chen, Wenliang; Huang, Yugang; Ye, Guodong

    2017-08-01

    Ring-opening polymerization of S-propargyl-cysteine-N-carboxyanhydride has been used to synthesize conformation switchable poly(S-propargyl-cysteine) starting with l-cysteine, dl- and d-cysteine. Then cationic polypeptides with different backbone chirality are obtained by nearly 100% side-chain grafting of cysteamine via thiol-yne click chemistry. The cationic polypeptides containing mixed conformations of β-sheets, β-turns and random coils are stable against pH, salt and temperature variations. The cationic polypeptides can condense siRNA at a low polypeptide/siRNA weight ratio to form nanoparticles with size depending on the backbone chirality. The cationic polypeptides derived from poly(S-propargyl-l or d-cysteine) are non-cytotoxic to HeLa and HepG2 cells, but interrupting the backbone chirality enhances the cytotoxicity sharply. The cationic polypeptides used for siRNA delivery show good transfection efficiency, but cell internalization process depends on the backbone chirality. The cationic polypeptide derived from the poly(S-propargyl-l-cysteine) is an appropriate siRNA vector with advantages of non-cytotoxicity and high transfection efficiency. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. The effect of exchangeable cations in clinoptilolite and montmorillonite on the adsorption of aflatoxin B1

    Directory of Open Access Journals (Sweden)

    DRAGAN STOJSIC

    2001-08-01

    Full Text Available The adsorption of aflatoxin B1 (AFB1 by cation-exchanged clinoptilolite zeolitic tuff and montmorillonite was investigated at 37°C and pH 3.8 from an aqueous electrolyte having a composition similar to that of gastric juices of animals. Both minerals were exchanged from the natural form to the sodium form and then to the Cu2+, Zn2+ and Co2+-rich forms. The cation exchange was different for the different cations, but in all cases the exchanges were larger on montmorillonite than on clinoptilolite. The degree of exchange on montmorillonite was 76 % for copper (from a total of CEC 0.95 meq/g, Cu2+ –0.73 meq/g and 85 % for zinc and cobalt. Under the same conditions (concentration, temperature, pH, contact time, the degree of exchange on zeolitic tuff was 12 % for Cu2+ (from a total CEC of 1.46 meq/g, Cu2+ –0.17 meq/g, 8 % for Zn2+ and 10 % for Co2+. Both groups of mineral adsorbents showed high AFB1 chemisorption indexes (ca. For the montmorillonite forms, ca ranged from 0.75 for the Cu-exchanged montmorillonite to 0.89 for the natural Ca-form, 0.90 for the Zn-exchanged form and 0.93 for the Co-exchanged montmorillonite. The adsorption of AFB1 on the different exchanged forms of clinoptilolite gave similar values of ca for the Cu and Ca forms (0.90 and values of 0.94 and 0.95 for the Zn- and Co-exchanged form. The impact of the mineral adsorbents on the reduction of essential nutrients present in animal feed (Cu, Zn, Mn and Co showed that the Ca-rich montmorillonite had a higher capability for the reduction of the microelements than the Ca-rich clinoptilolite.

  8. Increased localized delivery of piroxicam by cationic nanoparticles after intra-articular injection.

    Science.gov (United States)

    Kim, Sung Rae; Ho, Myoung Jin; Kim, Sang Hyun; Cho, Ha Ra; Kim, Han Sol; Choi, Yong Seok; Choi, Young Wook; Kang, Myung Joo

    2016-01-01

    Piroxicam (PRX), a potent nonsteroidal anti-inflammatory drug, is prescribed to relieve postoperative and/or chronic joint pain. However, its oral administration often results in serious gastrointestinal adverse effects including duodenal ulceration. Thus, a novel cationic nanoparticle (NP) was explored to minimize the systemic exposure and increase the retention time of PRX in the joint after intra-articular (IA) injection, by forming micrometer-sized electrostatic clusters with endogenous hyaluronic acid (HA) in the synovial cavity. PRX-loaded NPs consisting of poly(lactic- co -glycolic acid), Eudragit RL, and polyvinyl alcohol were constructed with the following characteristics: particle size of 220 nm, zeta potential of 11.5 mV in phosphate-buffered saline, and loading amount of 4.0% (w/w) of PRX. In optical and hyperspectral observations, the cationic NPs formed more than 50 μm-sized aggregates with HA, which was larger than the intercellular gaps between synoviocytes. In an in vivo pharmacokinetic study in rats, area under the plasma concentration-time curve (AUC 0-24 h ) and maximum plasma concentration ( C max ) of PRX after IA injection of the cationic NPs were <70% ( P <0.05) and 60% ( P <0.05), respectively, compared to those obtained from drug solution. Moreover, the drug concentration in joint tissue 24 h after dosing with the cationic NPs was 3.2-fold ( P <0.05) and 1.8-fold ( P <0.05) higher than that from drug solution and neutrally charged NPs, respectively. Therefore, we recommend the IA cationic NP therapy as an effective alternative to traditional oral therapy with PRX, as it increases drug retention selectively in the joint.

  9. Reducing the Risk of Cardiovascular Diseases in Non-selected Outpatients With Schizophrenia: A 30-Month Program Conducted in a Real-life Setting

    DEFF Research Database (Denmark)

    Hjorth, Peter; Juel, Anette; Hansen, Mette Vinther

    2017-01-01

    Background: The most common cause of premature death in people with schizophrenia is cardiovascular disease, partially explained by an unhealthy lifestyle, smoking, poor diet and sedentary behavior. We aimed to reduce cardiovascular risk factors. Method: Naturalistic follow-up study with 54 long......-term-treated non-selected outpatients with schizophrenia. The 30-month program consisted of individual guidance, group sessions and normal treatment and care offered in our clinic. Results: On average, the participating women reduced their waist circumference by 11.4. cm (P = 0.037), whereas the participating men...

  10. Binding properties of oxacalix[4]arenes derivatives toward metal cations

    International Nuclear Information System (INIS)

    Mellah, B.

    2006-11-01

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) 1 H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na + , K + , Ca 2+ , Pb 2+ and Mn 2+ of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li + , Ba 2+ , Zn 2+ and Hg 2+ . A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs + , Ba 2+ , Cu 2+ and Hg 2+ were noted. (author)

  11. Noncovalent cation-π interactions – their role in nature

    Directory of Open Access Journals (Sweden)

    Krzysztof Fink

    2014-11-01

    Full Text Available Non-covalent interactions play an extremely important role in organisms. The main non-covalent interactions in nature are: ion-ion interactions, dipole-dipole interactions, hydrogen bonds, and van der Waals interactions. A new kind of intermolecular interactions – cation-π interactions – is gaining increasing attention. These interactions occur between a cation and a π system. The main contributors to cation-π interactions are electrostatic, polarization and, to a lesser extent, dispersion interactions. At first, cation-π interactions were studied in a gas phase, with metal cation–aromatic system complexes. The characteristics of these complexes are as follows: an increase of cation atomic number leads to a decrease of interaction energy, and an increase of cation charge leads to an increase of interaction energy. Aromatic amino acids bind with metal cations mainly through interactions with their main chain. Nevertheless, cation-π interaction with a hydrophobic side chain significantly enhances binding energy. In water solutions most cations preferentially interact with water molecules rather than aromatic systems. Cation-π interactions occur in environments with lower accessibility to a polar solvent. Cation-π interactions can have a stabilizing role on the secondary, tertiary and quaternary structure of proteins. These interactions play an important role in substrate or ligand binding sites in many proteins, which should be taken into consideration when the screening of effective inhibitors for these proteins is carried out. Cation-π interactions are abundant and play an important role in many biological processes.

  12. Stability and recovery of DNA origami structure with cation concentration

    Science.gov (United States)

    Chen, Yi; Wang, Ping; Liu, Yang; Liu, Ting; Xu, Yan; Zhu, Shanshan; Zhu, Jun; Ye, Kai; Huang, Guang; Dannong, He

    2018-01-01

    We synthesized triangular and rectangular DNA origami nanostructures and investigated the stability and recovery of them under low cation concentration. Our results demonstrated that the origami nanostructures would melt when incubated in low cation concentration, and recover whilst kept in the concentration for less than 10 min. However, extending the incubation time would lead to irreversible melting. Our results show the possibility of application of DNA origami nanostructures for things such as a sensor for cation concentration response, etc.

  13. Controllable synthesis of α- and β-MnO2: cationic effect on hydrothermal crystallization

    International Nuclear Information System (INIS)

    Huang Xingkang; Lv Dongping; Yue Hongjun; Attia, Adel; Yang Yong

    2008-01-01

    α- and β-MnO 2 were controllably synthesized by hydrothermally treating amorphous MnO 2 obtained via a reaction between Mn 2+ and MnO 4 - , and cationic effects on the hydrothermal crystallization of MnO 2 were investigated systematically. The crystallization is believed to proceed by a dissolution-recrystallization mechanism; i.e. amorphous MnO 2 dissolves first under hydrothermal conditions, then condenses to recrystallize, and the polymorphs formed are significantly affected by added cations such as K + , NH 4 + and H + in the hydrothermal systems. The experimental results showed that K + /NH 4 + were in competition with H + to form polymorphs of α- and β-MnO 2 , i.e., higher relative K + /NH 4 + concentration favoured α-MnO 2 , while higher relative H + concentration favoured β-MnO 2

  14. Biomimetic Cationic Nanoparticles Based on Silica: Optimizing Bilayer Deposition from Lipid Films

    Directory of Open Access Journals (Sweden)

    Rodrigo T. Ribeiro

    2017-10-01

    Full Text Available The optimization of bilayer coverage on particles is important for a variety of biomedical applications, such as drug, vaccine, and genetic material delivery. This work aims at optimizing the deposition of cationic bilayers on silica over a range of experimental conditions for the intervening medium and two different assemblies for the cationic lipid, namely, lipid films or pre-formed lipid bilayer fragments. The lipid adsorption on silica in situ over a range of added lipid concentrations was determined from elemental analysis of carbon, hydrogen, and nitrogen and related to the colloidal stability, sizing, zeta potential, and polydispersity of the silica/lipid nanoparticles. Superior bilayer deposition took place from lipid films, whereas adsorption from pre-formed bilayer fragments yielded limiting adsorption below the levels expected for bilayer adsorption.

  15. The formation of singly and doubly cationized oligomers in SIMS

    International Nuclear Information System (INIS)

    Delcorte, A.; Wojciechowski, I.; Gonze, X.; Garrison, B.J.; Bertrand, P.

    2003-01-01

    The cationization of sputtered organic species via metal particle adduction is investigated using poly-4-methylstyrene molecules in combination with Cu, Pd, Ag and Au substrates. Metal-cationization occurs for these four substrates. The cationized molecule yields vary with the considered substrate and they are not correlated with the metal ion yields. In addition, double cationization with two metal particles is observed with a very significant intensity for Cu, Ag and Au supports. We interpret the results with an emission scheme in which excited molecules and metal atoms recombine above the surface and decay via electron emission, thereby locking the complex in the ionic state

  16. Liquid-like cationic sub-lattice in copper selenide clusters

    Science.gov (United States)

    White, Sarah L.; Banerjee, Progna; Jain, Prashant K.

    2017-02-01

    Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, `liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu+ ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu+ sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches.

  17. Tetracycline adsorption on kaolinite: pH, metal cations and humic acid effects.

    Science.gov (United States)

    Zhao, Yanping; Geng, Jinju; Wang, Xiaorong; Gu, Xueyuan; Gao, Shixiang

    2011-07-01

    Contamination of environmental matrixes by human and animal wastes containing antibiotics is a growing health concern. Because tetracycline is one of the most widely-used antibiotics in the world, it is important to understand the factors that influence its mobility in soils. This study investigated the effects of pH, background electrolyte cations (Li(+), Na(+), K(+), Ca(2+) and Mg(2+)), heavy metal Cu(2+) and humic acid (HA) on tetracycline adsorption onto kaolinite. Results showed that tetracycline was greatly adsorbed by kaolinite over pH 3-6, then decreased with the increase of pH, indicating that tetracycline adsorption mainly through ion exchange of cations species and complexation of zwitterions species. In the presence of five types of cations (Li(+), Na(+), K(+), Ca(2+) and Mg(2+)), tetracycline adsorption decreased in accordance with the increasing of atomic radius and valence of metal cations, which suggested that outer-sphere complexes formed between tetracycline and kaolinite, and the existence of competitor ions lead to the decreasing adsorption. The presence of Cu(2+) greatly enhanced the adsorption probably by acting as a bridge ion between tetracycline species and the edge sites of kaolinite. HA also showed a major effect on the adsorption: at pH kaolinite and need to be considered when assessing the environmental toxicity of tetracycline.

  18. A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres.

    Science.gov (United States)

    Fang, Xiaoliang; Chen, Cheng; Liu, Zhaohui; Liu, Pengxin; Zheng, Nanfeng

    2011-04-01

    Hollow mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO(2) accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.

  19. Cation exchange in a temporally fluctuating thin freshwater lens on top of saline groundwater

    Science.gov (United States)

    Eeman, S.; De Louw, P. G. B.; Van der Zee, S. E. A. T. M.

    2016-10-01

    In coastal-zone fields with a high groundwater level and sufficient rainfall, freshwater lenses are formed on top of saline or brackish groundwater. The fresh and the saline water meet at shallow depth, where a transition zone is found. This study investigates the mixing zone that is characterized by this salinity change, as well as by cation exchange processes, and which is forced by seepage and by rainfall which varies as a function of time. The processes are first investigated for a one-dimensional (1D) stream tube perpendicular to the interface concerning salt and major cation composition changes. The complex sequence of changes is explained with basic cation exchange theory. It is also possible to show that the sequence of changes is maintained when a two-dimensional field is considered where the upward saline seepage flows to drains. This illustrates that for cation exchange, the horizontal component (dominant for flow of water) has a small impact on the chemical changes in the vertical direction. The flow's horizontal orientation, parallel to the interface, leads to changes in concentration that are insignificant compared with those that are found perpendicular to the interface, and are accounted for in the 1D flow tube. Near the drains, differences with the 1D considerations are visible, especially in the longer term, exceeding 100 years. The simulations are compared with field data from the Netherlands which reveal similar patterns.

  20. Binding properties of oxacalix[4]arenes derivatives toward metal cations; Interactions entre cations metalliques et derives des oxacalix[4]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Mellah, B

    2006-11-15

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) {sup 1}H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na{sup +}, K{sup +}, Ca{sup 2+}, Pb{sup 2+} and Mn{sup 2+} of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li{sup +}, Ba{sup 2+}, Zn{sup 2+} and Hg{sup 2+}. A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs{sup +}, Ba{sup 2+}, Cu{sup 2+} and Hg{sup 2+} were noted. (author)

  1. Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques.

    Science.gov (United States)

    Casale, M; Oliveri, P; Casolino, C; Sinelli, N; Zunin, P; Armanino, C; Forina, M; Lanteri, S

    2012-01-27

    An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Selective versus non-selective culture medium for group B streptococcus detection in pregnancies complicated by preterm labor or preterm-premature rupture of membranes

    Directory of Open Access Journals (Sweden)

    Marcelo Luís Nomura

    Full Text Available The objective of this study was to identify group B streptococcus (GBS colonization rates and compare detection efficiency of selective versus non-selective culture media and anorectal versus vaginal cultures in women with preterm labor and preterm-premature rupture of membranes (PROM. A prospective cohort study of 203 women was performed. Two vaginal and two anorectal samples from each woman were collected using sterile swabs. Two swabs (one anorectal and one vaginal were placed separately in Stuart transport media and cultured in blood-agar plates for 48 hours; the other two swabs were inoculated separately in Todd-Hewitt selective media for 24 hours and then subcultured in blood-agar plates. Final GBS identification was made by the CAMP test. A hundred thrity-two cultures out of 812 were positive. The maternal colonization rate was 27.6%. Colonization rates were 30% for preterm PROM and 25.2% for preterm labor. Todd-Hewitt selective medium detected 87.5% and non-selective medium 60.7% GBS-positive women. Vaginal samples and anorectal samples had the same detection rate of 80.3%. Anorectal selective cultures detected 75% of carriers; 39% of GBS-positive women were detected only in selective medium. A combined vaginal-anorectal selective culture is appropriate for GBS screening in this population, minimizing laboratory costs.

  3. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  4. Use of a material conducting hydrogen cations

    International Nuclear Information System (INIS)

    Howe, A.T.; Shilton, M.G.

    1986-01-01

    The invention concerns a separator conducting hydrogenous for electrical devices, which contains at least one compound with the formula H(UO 2 )PO 4 x nH 2 O, H(UO 2 )AsO 4 x nH 2 O or H(UO 2 )IO 4 (OH) 2 x nH 2 O, where not more than 50% by weight of the H + is replaced by one or more cations, such as Li + , Na + , K + , NH 4 + , Cu 2+ , Mg 2+ , Ca 2+ , Ba 2+ , Sr 2+ , Pb 2+ , Fe 2+ , Co 2+ , Ni 2+ , Mn 2+ or Al 3+ . The electrical device having the separator can be an electrolysis cell, for example, an electro chromium cell. (H x WO 3 ), a hydrogen isotope enrichment device, a proton-sensitive electrode (eg for a pH meter), a battery or a fuel cell. (orig./MM) [de

  5. An investigation of mixed cation oxide glasses

    International Nuclear Information System (INIS)

    Brook, H.C.

    1999-02-01

    This study has been undertaken with several purposes in mind. Firstly, the author wished to ascertain whether EXAFS would show the mixed alkali (MAE) in a mixed alkali glass in shell parameters other than those for the first shell, as well as being a structural probe. Secondly, it was desired to see whether borate glasses show the MAE in EXAFS. Thirdly, the author attempted to ascertain whether cations of different charges would show an effect similar to the MAE. Fourthly, to use NMR as a second structure probe in an attempt to gain a better understanding of the structure. Fifthly, to perform electrical conductivity experiments to try to link the conductivity behaviour with structural changes. Finally, to attempt to develop a generalised explanation of the origins of the MAE and the variations in physical properties in glasses. (author)

  6. Retention of Cationic Starch onto Cellulose Fibres

    Science.gov (United States)

    Missaoui, Mohamed; Mauret, Evelyne; Belgacem, Mohamed Naceur

    2008-08-01

    Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV-vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan-based molecules and quantifying the ensuing mixture by measuring their absorbance at a Ι of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro-acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.

  7. Altered erythrocyte cation permeability in familial pseudohyperkalaemia.

    Science.gov (United States)

    Dagher, G; Vantyghem, M C; Doise, B; Lallau, G; Racadot, A; Lefebvre, J

    1989-08-01

    1. Erythrocyte cation transport pathways have been investigated in a family with pseudohyperkalaemia. 2. Ouabain- and bumetanide-resistant Na+ and K+ effluxes in three pseudohyperkalaemic patients were not different from those of control subjects when assessed at 37 degrees C. 3. When the temperature was decreased to 20 degrees C and 9 degrees C, K+ passive permeability markedly increased and Na+ permeability remained unchanged in these patients. In contrast, in control subjects a reduction in temperature caused a marked reduction in Na+ and K+ passive permeability. 4. These findings could account for the marked increase in plasma K+ concentration observed at subphysiological temperatures. 5. The Na+-K+ co-transport pathway was reduced in all members of the family, but the Na+-K+ pump was reduced in only two of them. These alterations were independent from the pseudohyperkalaemic state.

  8. A Cationic Smart Copolymer for DNA Binding

    Directory of Open Access Journals (Sweden)

    Tânia Ribeiro

    2017-11-01

    Full Text Available A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol methyl ether methacrylate (DEGMA and oligo(ethylene glycol methyl ether methacrylate (OEGMA, with the ratio DEGMA/OEGMA being used to choose the volume phase transition temperature of the polymer in water, tunable from ca. 25 to above 90 °C. The second block, of trimethyl-2-methacroyloxyethylammonium chloride (TMEC, is positively charged at physiological pH values and is used for DNA binding. The coacervate complexes between the block copolymer and a model single strand DNA are characterized by fluorescence correlation spectroscopy and fluorescence spectroscopy. The new materials offer good prospects for biomedical application, for example in controlled gene delivery.

  9. Cell Penetrating Peptides and Cationic Antibacterial Peptides

    Science.gov (United States)

    Rodriguez Plaza, Jonathan G.; Morales-Nava, Rosmarbel; Diener, Christian; Schreiber, Gabriele; Gonzalez, Zyanya D.; Lara Ortiz, Maria Teresa; Ortega Blake, Ivan; Pantoja, Omar; Volkmer, Rudolf; Klipp, Edda; Herrmann, Andreas; Del Rio, Gabriel

    2014-01-01

    Cell penetrating peptides (CPP) and cationic antibacterial peptides (CAP) have similar physicochemical properties and yet it is not understood how such similar peptides display different activities. To address this question, we used Iztli peptide 1 (IP-1) because it has both CPP and CAP activities. Combining experimental and computational modeling of the internalization of IP-1, we show it is not internalized by receptor-mediated endocytosis, yet it permeates into many different cell types, including fungi and human cells. We also show that IP-1 makes pores in the presence of high electrical potential at the membrane, such as those found in bacteria and mitochondria. These results provide the basis to understand the functional redundancy of CPPs and CAPs. PMID:24706763

  10. Identification of a cation-specific channel (TipA) in the cell wall of the gram-positive mycolata Tsukamurella inchonensis: the gene of the channel-forming protein is identical to mspA of Mycobacterium smegmatis and mppA of Mycobacterium phlei.

    Science.gov (United States)

    Dörner, Ursula; Maier, Elke; Benz, Roland

    2004-11-17

    Detergent extracts of whole cells of the Gram-positive bacterium Tsukamurella inchonensis ATCC 700082, which belongs to the mycolata, were studied for the presence of ion-permeable channels using lipid bilayer experiments. One channel with a conductance of about 4.5 nS in 1 M KCl was identified in the extracts. The channel-forming protein was purified to homogeneity by preparative SDS-PAGE. The protein responsible for channel-forming activity had an apparent molecular mass of about 33 kDa as judged by SDS-PAGE. Interestingly, the protein showed cross-reactivity with polyclonal antibodies raised against a polypeptide derived from MspA of Mycobacterium smegmatis similarly as the cell wall channel of Mycobacterium phlei. Primers derived from mspA were used to clone and sequence the gene of the cell wall channels of T. inchonensis (named tipA for T. inchonensis porin A) and M. phlei (named mppA for M. phlei porin A). Surprisingly, both genes, tipA and mppA, were found to be identical to mspA of M. smegmatis, indicating that the genomes of T. inchonensis, M. phlei and M. smegmatis contain the same genes for the major cell wall channel. RT-PCR revealed that tipA is transcribed in T. inchonensis and mppA in M. phlei. The results suggest that despite a certain distance between the three organisms, their genomes contain the same gene coding for the major cell wall channel, with a molecular mass of 22 kDa for the monomer.

  11. How mobile are sorbed cations in clays and clay rocks?

    Science.gov (United States)

    Gimmi, T; Kosakowski, G

    2011-02-15

    Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.

  12. In vivo toxicity of cationic micelles and liposomes

    DEFF Research Database (Denmark)

    Knudsen, Kristina Bram; Northeved, Helle; Ek, Pramod Kumar

    2015-01-01

    This study investigated toxicity of nanocarriers comprised of cationic polymer and lipid components often used in gene and drug delivery, formulated as cationic micelles and liposomes. Rats were injected intravenously with 10, 25 or 100 mg/kg and sacrificed after 24 or 48 h, or 24 h after the las...

  13. Synthesis of Cationic Core-Shell Latex Particles

    NARCIS (Netherlands)

    Dziomkina, N.; Hempenius, Mark A.; Vancso, Gyula J.

    2006-01-01

    Surfactant-free seeded (core-shell) polymerization of cationic polymer colloids is presented. Polystyrene core particles with sizes between 200 nm and 500 nm were synthesized. The number average diameter of the colloidal core particles increased with increasing monomer concentration. Cationic shells

  14. Effects of metallic cations in the beryl flotation

    International Nuclear Information System (INIS)

    Lima Leonel, C.M. de; Peres, A.E.C.

    1984-01-01

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.) [pt

  15. Does alkali cation binding to aromatic ring retard the fluxional ...

    Indian Academy of Sciences (India)

    A Kalpana

    2017-11-10

    Nov 10, 2017 ... the role of cation on haptotropic migration. Cation binding not only enhances the complex interaction energy but also delicately affects the fluxionality in the molecule by increasing the barrier to haptotropic shift of Cr(CO)3. The competing nature of the bifacial acids with sandwiched aromatic ring is ...

  16. Membrane potential change effects on cationic and neutral drug ...

    African Journals Online (AJOL)

    Membrane potential change effects on cationic and neutral drug - induced erythrocyte shape change and cellular uptake of drugs. A Nwafor, WT Coakley. Abstract. The effect of membrane potential change of the human erythrocytes on cationic drugs tetracaine and chlorpromazine and neutral drug benzyl alcohol induced ...

  17. Cation substitution induced blue-shift of optical band gap

    Indian Academy of Sciences (India)

    Cation substitution induced blue-shift of optical band gap in nanocrystalline Zn ( 1 − x ) Ca x O thin films deposited by sol–gel dip coating technique ... thin films giving 13.03% enhancement in theenergy gap value due to the electronic perturbation caused by cation substitution as well as deterioration in crystallinity.

  18. Base Cation Leaching From the Canopy of a Rubber ( Hevea ...

    African Journals Online (AJOL)

    Base cations are essential to the sustainability of forest ecosystems. They are important for neutralizing the acidifying effects of atmospheric deposition. There is the need for in-depth understanding of base cation depletion and leaching from forest canopy. This is important particularly due to the increasing acidification and ...

  19. Cationic Antimicrobial Peptides Inactivate Shiga Toxin-Encoding Bacteriophages

    Directory of Open Access Journals (Sweden)

    Manuel E. Del Cogliano

    2017-12-01

    Full Text Available Shiga toxin (Stx is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non-alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: (1 direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, (2 cationic properties are necessary but not sufficient for bacteriophage inactivation, and (3 inactivation by cationic peptides could be sequence (or structure specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

  20. A novel form of pectinesterase in tomato.

    Science.gov (United States)

    Warrilow, A G; Turner, R J; Jones, M G

    1994-03-01

    The pectinesterases in tomato pericarp were fractionated by cation exchange into four forms (A-D). Form A was the most abundant and C the second most abundant. Forms A-C were further purified by gel filtration, and antibodies were raised against A and C. Comparison of the different forms by dot blots and Western blots showed that although all three forms shared common immunological characteristics, there were also differences in their behaviour, indicative of structural differences. Form A had an N-terminal sequence identical to that published previously for the major pectinesterase in tomato fruit. In contrast, form C had a completely novel N-terminal sequence. Form A was absent from hypocotyls and roots. Forms B and C were present in comparable amounts in hypocotyls, while from C predominated in roots.

  1. Cation-cation "attraction": when London dispersion attraction wins over Coulomb repulsion.

    Science.gov (United States)

    Grimme, Stefan; Djukic, Jean-Pierre

    2011-03-21

    London forces are omnipresent in nature and relevant to molecular engineering. Proper tuning of their energetic contribution may stabilize molecular aggregates, which would be otherwise highly unstable by virtue of other overwhelming repulsive terms. The literature contains a number of such noncovalently bonded molecular aggregates, of which the "binding mode" has never been thoroughly settled. Among those are the emblematic cationic complexes of tetrakis(isonitrile)rhodium(I) studied by a number of researchers. The propensity of these complexes to spontaneously produce oligomers has been an "open case" for years. For the dimer [(PhNC)(4)Rh](2)(2+), one of the archetypes of such oligomers, density functional theory methods (DFT-D3) and wave function based spin-component-scaled second-order Møller-Plesset perturbation theory (SCS-MP2) quantum chemical calculations indicate that when the eight isonitrile ligands arrange spatially in an optimal π-stacked fashion, the energy due to dispersion not only overcomes coulombic repulsion but also the entropy penalty of complex formation. This central role of long-range electron correlation explains such cation-cation attractive interactions. Furthermore, the present findings relativize the role of the metal-metal "d(8)-d(8)" interactions, which are present on a relatively small scale compared to the effects of the ligands; d(8)-d(8) interactions represent about 10-15% of the total dispersion contribution to the binding energy.

  2. Titanomagnetite Curie temperatures: Effects of vacancies, chemical/cation ordering and thermal history

    Science.gov (United States)

    Jackson, M. J.; Bowles, J. A.; Lappe, S. C. L. L.; Solheid, P.

    2016-12-01

    Recent experimental work [Bowles et al, 2013, Nat. Commun.; Jackson and Bowles, 2014, G-cubed] has shown that the Curie temperatures (Tc) of intermediate-composition titanomagnetites (TM30-TM50) depend strongly on thermal history, with Tc increases of ≥100°C produced by moderate-temperature (300°-400° C) annealing in the lab or in slow natural cooling. Equally large decreases are produced by rapid cooling ("quenching") from higher temperatures. The phenomenon is robustly defined and repeatable, but the underlying mechanism remains enigmatic, presumably involving rearrangement of metal cations within the spinel lattice without any change in bulk composition. Previous studies [e.g., Moskowitz and Wanamaker, 1994, GRL; Lattard et al, 2006, JGR] have shown that cation deficiency controls Tc both directly, by changing the ferrous/ferric ratio, and indirectly, by affecting the cation ordering. Our new experiments examined the effects of oxidation state and nonstoichiometry on the magnitude of Tc changes produced by quenching/annealing. In our synthetic TMs these changes are generally relatively small (ΔTc100°), but when the samples are embedded in a reducing material (containing graphite), ΔTc becomes insignificant. These results strongly suggest that cation vacancies play an essential role in the cation rearrangements responsible for the observed changes in Tc. XMCD and low-temperature Mossbauer and magnetization measurements show no evidence of corresponding changes in ferrous/ferric site occupancy, and some form of octahedral-site chemical clustering or short-range ordering appears to be the best way to explain the large observed changes in Tc.

  3. Cooling of PAH cations studied with an electrostatic storage ring

    Science.gov (United States)

    Bernard, Jérôme; Chen, Li; Brédy, Richard; Ji, Mingchao; Ortéga, Céline; Matsumoto, Jun; Martin, Serge

    2017-10-01

    In this paper we discuss the production of molecular PAH cations using an ECR ion source and their subsequent cooling studied with an electrostatic storage ring, the Mini-Ring on a time range up to 10 ms. We show that the ECR ion source can produce high currents of small PAH cation, here naphthalene and anthracene cations. Then, we report experimental result for the cooling of three PAH cations (anthracene, naphthalene and pyrene) stored in our compact electrostatic storage ring (the Mini-Ring). We show that the Poincaré recurrent fluorescence plays a major role in the cooling process of those PAH cations. We show that for a given internal energy, the cooling rate is much smaller for pyrene than for anthracene and naphthalene. We conclude that the Poincaré recurrent fluorescence is less efficient due to smaller oscillator strength of the D2-D0 electronic transition for pyrene.

  4. Thermochemical stability of Soviet macroporous sulfonated cation-exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rukhlyada, N.N.; Plotnikova, V.P.; Roginskaya, B.S.; Znamenskii, Yu.P.; Zavodovskaya, A.S.; Dobrova, E.I.

    1988-10-20

    The purpose of this work was to study the influence of macroporosity on the thermochemical stability of sulfonated cation-exchangers. The investigations were carried out on commercial macroporous sulfonated cation-exchangers based on styrene-divinylbenzene copolymers. Study of the thermochemical stability of macroporous sulfonated cation-exchangers in dilute hydrogen peroxide solutions showed that the type of macroporosity has virtually no influence on their stability. The determining factor in thermal stability of macroporous cation-exchangers, as of the gel type, is the degree of cross-linking of the polymer matrix. The capacity loss of macroporous cation-exchangers during oxidative thermolysis is caused by destruction of the macromolecular skeleton and elution of fragments of polar chains containing sulfo groups into the solution.

  5. Accidental degeneracy in the spiropyran radical cation : charge transfer between two orthogonal rings inducing ultra-efficient reactivity

    NARCIS (Netherlands)

    Mendive-Tapia, David; Kortekaas, Luuk; Steen, Jorn D.; Perrier, Aurelie; Lasorne, Benjamin; Browne, Wesley R.; Jacquemin, Denis

    2016-01-01

    Photochromism of the spiropyran radical cation to the corresponding merocyanine form is investigated by a combination of electrochemical oxidation, UV/vis absorption spectroscopy, spectroelectrochemistry and first-principles calculations (TD-DFT, CAS-SCF and CAS-PT2). First, we demonstrate that the

  6. Synthesis of Quaternary Ammonium Salts of Tricyclic Cationic Drugs: A One-Pot Synthesis for the Bioorganic Chemistry Laboratory

    Science.gov (United States)

    Brunauer, Linda S.; Mogannam, Abid C.; Hwee, Won B.; Chen, James Y.

    2007-01-01

    A one-pot conversion of tricyclic cationic drugs to their quaternary ammonium forms is described for a widely used bioactive drug: chlorpromazine, a phenothiazine-based antipsychotic. After conversion to its free base, the parent drug was methylated using substoichiometric amounts of methyl iodide dissolved in ether; the charged quaternary…

  7. Infrared spectroscopy of gas-phase polycyclic aromatic hydrocarbon cations in the 10-50 m spectral range

    NARCIS (Netherlands)

    Bakker, J.M.; Redlich, B.; Meer, A.F.G.; Oomens, J.

    2011-01-01

    The gas-phase infrared spectra of four polycyclic aromatic hydrocarbon (PAH) cations have been recorded in the 10-50 μm (or 1000-200 cm-1) spectral range via IR multiple photon dissociation (IRMPD) spectroscopy. Ionized PAHs are formed by UV laser ionization in an effusive beam and subsequently

  8. Seven up. The incorporation of Li{sup +} cations in yttrium tungstate and silicate tungstate

    Energy Technology Data Exchange (ETDEWEB)

    Dorn, Katharina V.; Schustereit, Tanja; Strobel, Sabine; Hartenbach, Ingo [Institute for Inorganic Chemistry, University of Stuttgart (Germany)

    2017-12-13

    Lithium yttrium(III) oxidotungstate(VI), LiY{sub 5}W{sub 8}O{sub 32}, was synthesized by solid-state reaction of a mixture of lithium chloride, yttrium sesquioxide, and tungsten trioxide. It crystallizes monoclinically in space group C2/c (a = 1908.34(5) pm, b = 561.80(1) pm, c = 1147.22(3) pm, β = 111.255(2) , Z = 2). The structure comprises one mixed Li{sup +}/Y{sup 3+} cationic position (molar ratio Li:Y1 = 1:1) and one cationic position exclusively occupied by Y{sup 3+} cations. All W{sup 6+} cations are surrounded by six O{sup 2-} anions, forming distorted octahedral coordination polyhedra, which are mutually linked by both edges and vertices to cascaded {sup 2}{sub ∞}{[W_4O_1_6]"8"-} layers. Lithium yttrium(III) oxidosilicate(IV) oxidotungstate(VI), LiY{sub 5}[SiO{sub 4}]{sub 2}[WO{sub 4}]{sub 4}, was obtained as by-product in the synthesis of YF[WO{sub 4}] by sintering a mixture of Y{sub 2}O{sub 3}, YF{sub 3}, and WO{sub 3} with lithium chloride as fluxing agent in sealed silica ampoules. It crystallizes orthorhombically in space group Pban (a = 512.08(4) pm, b = 1673.35(12) pm, c = 493.68(4) pm, Z = 1) bearing one mixed crystallographic position occupied by Li{sup +} and Y{sup 3+} cations in a molar ratio of 1:3 and one exclusive Y{sup 3+} position in its structure. The coordination polyhedra around the Si{sup 4+} and W{sup 6+} cations are isolated tetrahedra built up by four O{sup 2-} anions each. The crystal structure of this silicate tungstate can be derived from the scheelite-type structure by inserting anionic {sup 2}{sub ∞}{(Y2[SiO_4])"-} layers between cationic {sup 2}{sub ∞}{[(Li/Y1)_2[WO_4]_2]"+} double layers. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Increasing Base Cations in Streams: Another Legacy of Deicing Salts?

    Science.gov (United States)

    Helton, A. M.; Barclay, J. R.; Bellucci, C.; Rittenhouse, C.

    2017-12-01

    Elevated use of deicing salts directly increases sodium chloride inputs to watersheds. Sodium can accumulate in soils over time and has the potential to leach other cations (e.g., calcium, magnesium, and potassium) from the soil through cation exchange. We hypothesize that increased use of deicing salts results in a legacy of soils depleted in non-sodium base cations with loss of cations to receiving waters. The goal of this project is to quantify temporal trends in base cations and chloride in streams and rivers across the United States. We used Weighted Regressions on Time, Discharge, and Season (WRTDS) to analyze trends in base cations. Our preliminary analysis of 10 rivers in Connecticut with chemical periods of record ranging from 24 - 64 years (median = 55 years), shows that the flux of base cations is increasing in all sites (25 - 366 103 meq ha-1 yr-1 yr-1), driven largely by increases in sodium (23 - 222 103 meq ha-1 yr-1 yr-1), the dominant cation in 7 of the sites. Chloride is also increasing at all sites (26 - 261 103 meq ha-1 yr-1 yr-1), which, in combination with salt use trends, suggests a road salt source for the increased sodium. Non-sodium cations are also increasing in 9 of the sites (8 - 54 103 meq ha-1 yr-1 yr-1), though they are not directly added with most deicing salts. We will compare these trends to other long-term sites across the United States, and quantify relationships between cation trends and land cover, road density, and snowfall.

  10. Association of alkali and alkaline earth metal cations with radical-anions of 9-fluorenone and 9.10-anthraquinone in dimethyl formamide medium

    International Nuclear Information System (INIS)

    Karpinets, A.P.; Bezuglyj, V.D.; Svetlichnaya, T.M.

    1988-01-01

    The polarographic method is used to estimate the stability of associates formed in dimethyl formamide by the products of one-electron reduction of 9-fluorenone and 9.10-anthraquinone with cations of alkali and alkali earth metals. It is shown that the strength of 9-fluorenone and 9.10-anthraquinone radical anion associates studied increases with cation charge increase and decrease of its crystallographic radius

  11. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

  12. Anaerobic toxicity of cationic silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gitipour, Alireza; Thiel, Stephen W. [Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH (United States); Scheckel, Kirk G. [USEPA, Office of Research and Development, Cincinnati, OH (United States); Tolaymat, Thabet, E-mail: tolaymat.thabet@epa.gov [USEPA, Office of Research and Development, Cincinnati, OH (United States)

    2016-07-01

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag{sup +} under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10–15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L{sup −1}, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L{sup −1} as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag{sup +}. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L{sup −1} as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. - Highlights: • At concentrations -1 the anaerobic decomposition process was not impacted. • An impact on the microbial community at concentrations -1 were observed. • At high concentrations (100 mg L{sup −1}), the cationic BPEI-AgNPs demonstrated toxicity. • Toxicity was demonstrated without the presence of oxidative dissolution of silver. • A one size fits all approach for the evaluation of NPs may not be accurate.

  13. Superparamagnetic cation-exchange adsorbents for bioproduct recovery from crude process liquors by high-gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L; Hobley, Timothy John

    2004-01-01

    of epichlorohydrin formed on the particle surface. The resultant cation-exchanger had a maximum lysozyme binding capacity of 272 mg g(-1) and a dissociation constant of 0.73 muM. Using lysozyme as a model protein in small-scale studies, appropriate conditions were then selected for the capture of lactoperoxidase......Different routes were screened for the preparation of superparamagnetic cation-exchange adsorbents for the capture of proteins using high-gradient magnetic fishing. Starting from a polyglutaraldehyde-coated base particle, the most successful of these involved attachment of sulphite to oligomers...

  14. Formation of ZnSe/Bi2Se3 QDs by surface cation exchange and high photothermal conversion

    Directory of Open Access Journals (Sweden)

    Guozhi Jia

    2015-08-01

    Full Text Available Water-dispersed core/shell structure ZnSe/Bi2Se3 quantum dots were synthesized by ultrasonicwave-assisted cation exchange reaction. Only surface Zn ion can be replaced by Bi ion in ZnSe quantum dots, which lead to the ultrathin Bi2Se3 shell layer formed. It is significance to find to change the crystal of QDs due to the acting of ultrasonicwave. Cation exchange mechanism and excellent photothermal conversion properties are discussed in detail.

  15. Investigations on complexing cation exchangers and their use for trace analysis in natural waters

    International Nuclear Information System (INIS)

    Lang, H.

    1991-12-01

    The practicability of cation preconcentrations from natural waters by use of EDTrA- and 5-s-oxine- celluloses has been studied. For that purpose the protonation constants as well as the complexation capacities were determined by use of acid/base titrations. In additional titration experiments the complex stability constants for Cu 2+ , Mn 2+ , Co 2+ , Ni 2+ and Ca 2+ were determined examplarely. The interpretation of the experiments was performed using an optimised fit between calculated and experimentally determined pH-titration curves. Calculations have been done by the computer code 'MINEQL'. The determined stability constants are in the same order of magnitude as those given in literature for the water soluble complexes of EDTA, NTA or 5-s-oxine. The preconcentration of cations from natural water samples occurs in accordance with the theoretical predictions. Not ignorable disturbances appear for cations forming hydroxides or oxides in neutral or weakly acidic solutions. By use of radioactive isotopes for Sn 2+ , Zn 4+ and Nb 5+ it can be shown that those ions may form particles or colloids in natural waters. These particles will be filtered in the columns packed with the celluloses and can hardly be removed from there. (author)

  16. Determination of correlation times from selective and non-selective spin-lattice relaxation rates and their use in drug-drug and drug-albumin interaction studies

    Directory of Open Access Journals (Sweden)

    Tinoco Luzineide Wanderley

    1999-01-01

    Full Text Available The effects of the changes in sample concentration on the NMR chemical shifts and on the selective and non-selective spin-lattice relaxation rates (R1S and R1NS of the three isomers of nitrobenzaldeyde guanyl hydrazone (NBGH pure and with bovine serum albumin (BSA were measured in solution. The results wereused to determine the correlation times (tauc, showing that the degree of intermolecular drug-drug association varies with the nitro group position on the ring and that this degree of association interferes with the interaction of these drugs with BSA. The results suggest that the degree of drug-drug and drug-BSA association are related to the in vitro anti-Trypanosoma cruzi activity of these compounds.

  17. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites.

  18. Aspirin, ibuprofen, and other non-steroidal anti-inflammatory drugs in cancer prevention: a critical review of non-selective COX-2 blockade (review).

    Science.gov (United States)

    Harris, Randall E; Beebe-Donk, Joanne; Doss, Hani; Burr Doss, Deborah

    2005-04-01

    We comprehensively reviewed the published scientific literature on non-steroidal anti-inflammatory drugs (NSAIDs) and cancer and evaluated results based upon epidemiologic criteria of judgment: consistency of results, strength of association, dose response, molecular specificity, and biological plausibility. Sufficient data from 91 epidemiologic studies were available to examine the dose response of relative risk and level of NSAID intake for ten human malignancies. Dose response curves were fitted by exponential regression. Results showed a significant exponential decline in the risk with increasing intake of NSAIDs (primarily aspirin or ibuprofen) for 7-10 malignancies including the four major types: colon, breast, lung, and prostate cancer. Daily intake of NSAIDs, primarily aspirin, produced risk reductions of 63% for colon, 39% for breast, 36% for lung, and 39% for prostate cancer. Significant risk reductions were also observed for esophageal (73%), stomach (62%), and ovarian cancer (47%). NSAID effects became apparent after five or more years of use and were stronger with longer duration. Observed protective effects were also consistently stronger for gastrointestinal malignancies (esophagus, stomach, and colon). Results for pancreatic, urinary bladder, and renal cancer were inconsistent. Initial epidemiologic studies of malignant melanoma, Hodgkin's disease, and adult leukemia also found that NSAIDs are protective. A few studies suggest that ibuprofen has stronger anticancer effects than aspirin, particularly against breast and lung cancer. Overexpression of cyclooxygenase-2 (COX-2) and increased prostaglandin biosynthesis correlates with carcinogenesis and metastasis at most anatomic sites. Preclinical investigations provide consistent evidence that both selective and non-selective NSAIDs effectively inhibit chemically-induced carcinogenesis of epithelial tumors. This review provides compelling and converging evidence that regular intake of NSAIDs that non-selectively

  19. Selective versus non-selective suppression of nitric oxide synthase on regional hemodynamics in rats with or without LPS-induced endotoxemia.

    Science.gov (United States)

    Cheng, Xing; Leung, Susan W S; Lo, Lawrence S; Pang, Catherine C Y

    2003-04-01

    The late phase of severe septic shock is associated with reduced cardiac output (CO) and activation of the inducible isoform of nitric oxide synthase (NOS). This study examined the effects of 1400 W (N-3-aminomethyl-benzyl-acetamidine), a new selective inhibitor of inducible NOS (iNOS), relative to those of N(G)-nitro-L-arginine (L-NNA, non-selective inhibitor of NOS) and the vehicle, on mean arterial pressure (MAP), CO, total peripheral resistance (TPR) and tissue blood flow (BF) in thiobutabarbital-anesthetized rats with lipopolysaccharide (LPS, 10 mg/kg, i.v.) induced endotoxemia. At 2.5 as well as 4 h after injection of LPS, MAP, CO, and BF of the stomach, skeletal muscle and skin were decreased, but TPR was increased, BF to the heart and kidneys were also decreased at 4 h after injection of LPS. Treatment of endotoxemic rats with 1400 W (3 mg/kg followed by 3 mg/kg/h, i.v.) at 2.5 h after endotoxin challenge prevented the late phase fall in MAP without exacerbating the decreases in CO and tissue BF. In contrast, treatment with L-NNA (8 mg/kg followed by 3 mg/kg/h, i.v.) at 2.5 h did not prevent the decline in MAP in the LPS-treated rats. Furthermore, CO drastically decreased, TPR markedly increased, and BF to the heart, brain, intestine and skeletal muscle were decreased at 4 h relative to the readings in saline- or 1400 W-treated endotoxemic rats. Therefore, selective inhibition of iNOS by 1400 W restores MAP without compromising CO, but non-selective inhibition of NOS is detrimental at the late stage of septic shock.

  20. Efficient scavenging of β-carotene radical cations by antiinflammatory salicylates

    DEFF Research Database (Denmark)

    Cheng, Hong; Liang, Ran; Han, Rui-Min

    2014-01-01

    by the anion of salicylic acid with 2.2 × 10 L mol s, but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced......The radical cation generated during photobleaching of β-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k = 3.2 × 10 L mol s in 9:1 v/v chloroform-methanol at 23 °C, less efficiently...... rearrangements. The relative scavenging rate of the β-carotene radical cation by the three salicylates is supported by DFT-calculations....

  1. Ability of a montmorillonitic clay to interact with cationic and anionic dyes in aqueous solutions

    Science.gov (United States)

    Pleşa Chicinaş, R.; Bedelean, H.; Stefan, R.; Măicăneanu, A.

    2018-02-01

    A montmorillonitic clay in raw and treated forms (size-fractionated, organoclay, Al pillared) was evaluated as adsorbent for cationic (toluidine blue - TB and malachite green - MG) and anionic (Congo red - CR) dyes. A thorough characterization using XRD, SEM-EDS, N2 adsorption, and FTIR of the considered samples was realized, all highlighting the structural changes after various treatments. UV-VIS analysis demonstrated the interaction between dyes and the adsorbent surface. The investigation of the effects of various experimental parameters using a batch adsorption technique showed that ON has a high adsorption potential for cationic dyes (33 and 39 mg/g in case of TB and MG, respectively). The kinetic study indicated that the adsorption process followed the pseudo-second-order model, while Freundlich isotherm showed a favorable adsorption. The calculated values of Gibbs free energy suggested also that the adsorption is spontaneous and is more favorable at higher temperatures.

  2. Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

    Science.gov (United States)

    Akbaba, Hasan; Karagöz, Uğur; Selamet, Yusuf; Kantarcı, A. Gülten

    2017-03-01

    The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15-17 emu g-1 for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting.

  3. Efficient scavenging of β-carotene radical cations by antiinflammatory salicylates.

    Science.gov (United States)

    Cheng, Hong; Liang, Ran; Han, Rui-Min; Zhang, Jian-Ping; Skibsted, Leif H

    2014-02-01

    The radical cation generated during photobleaching of β-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k2 = 3.2 × 10(9) L mol(-1) s(-1) in 9 : 1 v/v chloroform-methanol at 23 °C, less efficiently by the anion of salicylic acid with 2.2 × 10(8) L mol(-1) s(-1), but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced rearrangements. The relative scavenging rate of the β-carotene radical cation by the three salicylates is supported by DFT-calculations.

  4. Formation and decay of the methylviologen radical cation in the solid phase

    Science.gov (United States)

    Wolszczak, M.; Stradowski, Cz.

    Absorption and emission spectra of the methylviologen (MV 2+)/ tris (2,2'-bipyridine) ruthenium(II)[Ru(bpy) 2+3 system in a variety of solid systems—ethylene glycol-water glass, polymer foil, cellulose, and wool—have been studied at 4.2, 77, and 298 K. It was found that MV 2+ always quenches the luminescence of ∗ Ru(bpy)2+3. However, the MV +. radical cation, which is generated at 298 K as a result of a quenching process, is not generated at 77 and 4.2 K. Lowering of the temperature probably prevents the diffusion of electron donor to the oxidized form of photosensitizer and enables instantaneous back reaction. The formation of the MV +. radical cation under the influence of light λ > 300 nm at low and ambient temperatures has been studied. The crucial role of water in the oxidation of MV +. was confirmed in a pulse radiolysis experiment.

  5. Radical Cations and Acid Protection during Radiolysis

    International Nuclear Information System (INIS)

    Mincher, Bruce J.; Zarzana, Christopher A.; Mezyk, Stephen P.

    2016-01-01

    Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade in pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO 3 . It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.

  6. Antiviral activity of cationic amphiphilic drugs.

    Science.gov (United States)

    Salata, Cristiano; Calistri, Arianna; Parolin, Cristina; Baritussio, Aldo; Palù, Giorgio

    2017-05-01

    Emerging and reemerging viral infections represent a major concern for human and veterinary public health and there is an urgent need for the development of broad-spectrum antivirals. Areas covered: A recent strategy in antiviral research is based on the identification of molecules targeting host functions required for infection of multiple viruses. A number of FDA-approved drugs used to treat several human diseases are cationic amphiphilic drugs (CADs) that have the ability to accumulate inside cells affecting several structures/functions hijacked by viruses during infection. In this review we summarized the CADs' chemical properties and effects on the cells and reported the main FDA-approved CADs that have been identified so far as potential antivirals in drug repurposing studies. Expert commentary: Although there have been concerns regarding the efficacy and the possible side effects of the off-label use of CADs as antivirals, they seem to represent a promising starting point for the development of broad-spectrum antiviral strategies. Further knowledge about their mechanism of action is required to improve their antiviral activity and to reduce the risk of side effects.

  7. Radical Cations and Acid Protection during Radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zarzana, Christopher A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mezyk, Stephen P. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-09

    Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade in pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO3. It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.

  8. Interaction of cationic drugs with liposomes.

    Science.gov (United States)

    Howell, Brett A; Chauhan, Anuj

    2009-10-20

    Interactions between cationic drugs and anionic liposomes were studied by measuring binding of drugs and the effect of binding on liposome permeability. The measurements were analyzed in the context of a continuum model based on electrostatic interactions and a Langmuir isotherm. Experiments and modeling indicate that, although electrostatic interactions are important, the fraction of drug sequestered in the double-layer is negligible. The majority of drug enters the bilayer with the charged regions interacting with the charged lipid head groups and the lipophilic regions associated with the bilayer. The partitioning of the drug can be described by a Langmuir isotherm with the electrostatic interactions increasing the sublayer concentration of the drug. The binding isotherms are similar for all tricyclic antidepressants (TCA). Bupivacaine (BUP) binds significantly less compared to TCA because its structure is such that the charged region has minimal interactions with the lipid heads once the BUP molecule partitions inside the bilayer. Conversely, the TCAs are linear with distinct hydrophilic and lipophilic regions, allowing the lipophilic regions to lie inside the bilayer and the hydrophilic regions to protrude out. This conformation maximizes the permeability of the bilayer, leading to an increased release of a hydrophilic fluorescent dye from liposomes.

  9. Water Adsorption on Free Cobalt Cluster Cations.

    Science.gov (United States)

    Kiawi, Denis M; Bakker, Joost M; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L B F M

    2015-11-05

    Cationic cobalt clusters complexed with water Con(+)-H2O (n = 6-20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200-1700 cm(-1) spectral range. All spectra exhibit a resonance close to the 1595 cm(-1) frequency of the free water bending vibration, indicating that the water molecule remains intact upon adsorption. For n = 6, the frequency of this band is blue-shifted, but it gradually converges to the free water value with increasing cluster size. In the lower-frequency range (200-650 cm(-1)) the spectra contain several bands which show a very regular frequency evolution, suggesting that the exact cluster geometry has little effect on the water-surface interaction. Density functional theory (DFT) calculations are carried out at the OPBE/TZP level for three representative sizes (n = 6, 9, 13) and indicate that the vibrations responsible for the resonances correspond to bending and torsional modes between the cluster and water moieties. The potential energy surfaces describing these interactions are very shallow, making the calculated harmonic frequencies and IR intensities very sensitive to small geometrical perturbations. We conclude that harmonic frequency calculations on (local) minima structures provide insufficient information for these types of cluster complexes and need to be complemented with calculations that provide a more extensive sampling of the potential energy surface.

  10. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Anne-Marie Ellegaard

    2016-07-01

    Full Text Available Non-small cell lung cancer (NSCLC is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy.

  11. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    Science.gov (United States)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja

    2016-07-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  12. Multi-signalling cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline based hetarylazo dye.

    Science.gov (United States)

    Kaur, Paramjit; Sareen, Divya; Kaur, Mandeep; Singh, Kamaljit

    2013-05-17

    We investigated the cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline appended hetarylazo dye via chromogenic and electrochemical transduction channels. The binding pocket constituting both the pyridyl as well as aniline nitrogen atoms acts as recognition site for the cations and consequent perturbation in the intramolecular charge-transfer prevailing in the dye results in the chromogenic response manifested in the form of hypsochromic shift in the intramolecular charge-transfer band and the attendant naked-eye color changes. The dye exhibits significant changes in its electrochemical behaviour in the presence of cations. The experimental results are also rationalized by time-dependent density functional theory (TD-DFT) calculations. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Iridium containing honeycomb Delafossites by topotactic cation exchange.

    Science.gov (United States)

    Roudebush, John H; Ross, K A; Cava, R J

    2016-06-07

    We report the structure and magnetic properties of two new iridium-based honeycomb Delafossite compounds, Cu3NaIr2O6 and Cu3LiIr2O6, formed by a topotactic cation exchange reaction. The starting materials Na2IrO3 and Li2IrO3, which are based on layers of IrO6 octahedra in a honeycomb lattice separated by layers of alkali ions, are transformed to the title compounds by a topotactic exchange reaction through heating with CuCl below 450 °C; higher temperature reactions cause decomposition. The new compounds display dramatically different magnetic behavior from their parent compounds - Cu3NaIr2O6 has a ferromagnetic like magnetic transition at 10 K, while Cu3LiIr2O6 retains the antiferromagnetic transition temperature of its parent compound but displays significantly stronger dominance of antiferromagnetic coupling between spins. These results reveal that a surprising difference in the magnetic interactions between the magnetic Ir ions has been induced by a change in the non-magnetic interlayer species. A combination of neutron and X-ray powder diffraction is used for the structure refinement of Cu3NaIr2O6 and both compounds are compared to their parent materials.

  14. Comprehensive study of tartrazine/cationic surfactant interaction.

    Science.gov (United States)

    Shahir, Afshin Asadzadeh; Javadian, Soheila; Razavizadeh, Bi Bi Marzieh; Gharibi, Hussein

    2011-12-15

    Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

  15. Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals.

    Science.gov (United States)

    Fenton, Julie L; Schaak, Raymond E

    2017-06-01

    The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu 2-x S transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu 2-x S. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu 2-x S, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Preparation, characterization, and efficient transfection of cationic liposomes and nanomagnetic cationic liposomes

    Directory of Open Access Journals (Sweden)

    Samadikhah HR

    2011-10-01

    Full Text Available Hamid Reza Samadikhah1,*, Asia Majidi2,*, Maryam Nikkhah2, Saman Hosseinkhani11Department of Biochemistry, 2Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran *These authors contributed equally to this work Purpose: Cationic liposomes (CLs are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies. Patients and methods: CLs and magnetic cationic liposomes (MCLs were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3 were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome–plasmid DNA complexes formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3; transfection efficiency and gene expression level was evaluated by luciferase assay. Results: High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine™. Conclusion: Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to

  17. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Programa Nacional de Gestion de Residuos Radiactivos, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Bianchi, Hugo L. [Gerencia de Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); ECyT, Universidad Nacional de General San Martin, Campus Miguelete, Ed. Tornavias, Martin de Irigoyen 3100, 1650 San Martin (Argentina); Conicet, Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Manzini, Alberto C. [Programa Nacional de Gestion de Residuos Radiactivos, Comision Nacional de Energia Atomica, Av. Del Libertador 8250, CP 1429, Ciudad Autonoma de Buenos Aires (Argentina)

    2012-05-15

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ni{sup 2+} in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH{sub 4}) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 Degree-Sign C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 Degree-Sign C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 Degree-Sign C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 Degree-Sign C reached a plateau or

  18. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, Lowell D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Focsan, A Ligia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Konovalova, Tatyana A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence, Jesse [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bowman, Michael K [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Molnar, Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deli, Jozsef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2007-06-11

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car•+) but also neutral radicals (#Car•) by proton loss from the methyl groups at positions 5 or 5', and possibly 9 or 9' and 13 or 13'. Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car•+ which agree with the ENDOR for carotenoid α-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity [Lycopene (III) versus 8'-apo-β-caroten-8'-al (IV)]; hydrogen bonding [Lutein (V) versus III]; host [silica-alumina versus MCM-41 molecular sieve]; and substituted metal in MCM-41. Loss of H+ from the 5(5'), 9(9') or 13(13') methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I •+…Chl•-), lower in energy than 1Chl*. Formation of I •+ results in bond

  19. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    International Nuclear Information System (INIS)

    Kispert, Lowell D.; Focsan, A. Ligia; Konovalova, Tatyana A.; Lawrence, Jesse; Bowman, Michael K.; Dixon, David A.; Molnar, Peter; Deli, Jozsef

    2007-01-01

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car ·+ ) but also neutral radicals ((number s ign)Car · ) by proton loss from the methyl groups at positions 5 or 5(prime), and possibly 9 or 9(prime) and 13 or 13(prime). Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car # center d ot# + which agree with the ENDOR for carotenoid π-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity (Lycopene (III) versus 8(prime)-apo-β-caroten-8(prime)-al (IV)); hydrogen bonding (Lutein (V) versus III); host (silica-alumina versus MCM-41 molecular sieve); and substituted metal in MCM-41. Loss of H + from the 5(5(prime)), 9(9(prime)) or 13(13(prime)) methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1 Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I # center d ot# + ...Chl # center d ot# - ), lower in

  20. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    International Nuclear Information System (INIS)

    Luca, Vittorio; Bianchi, Hugo L.; Manzini, Alberto C.

    2012-01-01

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs + , Sr 2+ , Co 2+ , Ni 2+ in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH 4 ) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 °C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200–600 °C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 °C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 °C reached a plateau or steady-state within the first 24 h increasing only

  1. Evaluation of phenomena affecting diffusion of cations in compacted bentonite

    International Nuclear Information System (INIS)

    Muurinen, A.; Lehikoinen, J.

    1995-04-01

    In a number of diffusion studies, contradictions between the apparent diffusivities of cations and their distribution coefficients in bentonite have been found. Two principal reasons have been offered as explanations for this discrepancy; diffusion of the sorbed cations, often called surface diffusion, and the decrease of sorption in compacted clay compared to a sorption value obtained from a batch experiment. In the study the information available from the literature on sorption-diffusion mechanisms of cations in bentonite has been compiled and re-interpreted in order to improve the understanding of the diffusion process. (103 refs., 23 figs., 8 tabs.)

  2. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    OpenAIRE

    Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas?phase Cl?X and [HCl?X]+ complexes for X+=?H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl? and HCl for the various cations. The Cl?X bond becomes longer and weaker along X+?=?H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence ...

  3. Endomembrane Cation Transporters and Membrane Trafficking

    Energy Technology Data Exchange (ETDEWEB)

    Sze, Heven [Univ. of Maryland, College Park, MD (United States). Dept. of Cell Biology & Molecular Genetics

    2017-04-01

    Multicellular, as well as unicellular, organisms have evolved mechanisms to regulate ion and pH homeostasis in response to developmental cues and to a changing environment. The working hypothesis is that the balance of fluxes mediated by diverse transporters at the plasma membrane and in subcellular organelles determines ionic cellular distribution, which is critical for maintenance of membrane potential, pH control, osmolality, transport of nutrients, and protein activity. An emerging theme in plant cell biology is that cells respond and adapt to diverse cues through changes of the dynamic endomembrane system. Yet we know very little about the transporters that might influence the operation of the secretory system in plants. Here we focus on transporters that influence alkali cation and pH homeostasis, mainly in the endomembrane/ secretory system. The endomembrane system of eukaryote cells serves several major functions: i) sort cargo (e.g. enzymes, transporters or receptors) to specific destinations, ii) modulate the protein and lipid composition of membrane domains through remodeling, and iii) determine and alter the properties of the cell wall through synthesis and remodeling. We had uncovered a novel family of predicted cation/H+ exchangers (CHX) and K+ efflux antiporters (KEA) that are prevalent in higher plants, but rare in metazoans. We combined phylogenetic and transcriptomic analyses with molecular genetic, cell biological and biochemical studies, and have published the first reports on functions of plant CHXs and KEAs. CHX studied to date act at the endomembrane system where their actions are distinct from the better-studied NHX (Na/K-H+ exchangers). Arabidopsis thaliana CHX20 in guard cells modulate stomatal opening, and thus is significant for vegetative survival. Other CHXs ensure reproductive success on dry land, as they participate in organizing pollen walls, targeting of pollen tubes to the ovule or promoting

  4. Hydrophobicity drives the cellular uptake of short cationic peptide ligands.

    Science.gov (United States)

    Gupta, Anju; Mandal, Deendayal; Ahmadibeni, Yousef; Parang, Keykavous; Bothun, Geoffrey

    2011-06-01

    Short cationic linear peptide analogs (LPAs, prepared as Arg-C( n )-Arg-C( n )-Lys, where C( n ) represents an alkyl linkage with n = 4, 7 or 11) were synthesized and tested in human breast carcinoma BT-20 and CCRF-CEM leukemia cells for their application as targeting ligands. With constant LPA charge (+4), increasing the alkyl linkage increases the hydrophobic/hydrophilic balance and provides a systematic means of examining combined electrostatic and hydrophobic peptide-membrane interactions. Fluorescently conjugated LPA-C(11) (F-LPA-C(11)) demonstrated significant uptake, whereas there was negligible uptake of the shorter LPAs. By varying temperature (4°C and 37°C) and cell type, the results suggest that LPA-C(11) internalization is nonendocytic and nonspecific. The effect of LPA binding on the phase behavior, structure, and permeability of model membranes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine (DPPC/DPPS, 85/15) was studied using differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), and fluorescence leakage studies to gain insight into the LPA uptake mechanism. While all LPAs led to phase separation, LPA-C(11), possessing the longest alkyl linkage, was able to penetrate into the bilayer and caused holes to form, which led to membrane disintegration. This was confirmed by rapid and complete dye release by LPA-C(11). We propose that LPA-C(11) achieves uptake by anchoring to the membrane via hydrophobicity and forming transient membrane voids. LPAs may be advantageous as drug transporter ligands because they are small, water soluble, and easy to prepare.

  5. Opposing effects of cationic antimicrobial peptides and divalent cations on bacterial lipopolysaccharides

    Science.gov (United States)

    Smart, Matthew; Rajagopal, Aruna; Liu, Wing-Ki; Ha, Bae-Yeun

    2017-10-01

    The permeability of the bacterial outer membrane, enclosing Gram-negative bacteria, depends on the interactions of the outer, lipopolysaccharide (LPS) layer, with surrounding ions and molecules. We present a coarse-grained model for describing how cationic amphiphilic molecules (e.g., antimicrobial peptides) interact with and perturb the LPS layer in a biologically relevant medium, containing monovalent and divalent salt ions (e.g., Mg2+). In our approach, peptide binding is driven by electrostatic and hydrophobic interactions and is assumed to expand the LPS layer, eventually priming it for disruption. Our results suggest that in parameter ranges of biological relevance (e.g., at micromolar concentrations) the antimicrobial peptide magainin 2 effectively disrupts the LPS layer, even though it has to compete with Mg2+ for the layer. They also show how the integrity of LPS is restored with an increasing concentration of Mg2+. Using the approach, we make a number of predictions relevant for optimizing peptide parameters against Gram-negative bacteria and for understanding bacterial strategies to develop resistance against cationic peptides.

  6. Removal of cesium ions from clays by cationic surfactant intercalation.

    Science.gov (United States)

    Park, Chan Woo; Kim, Bo Hyun; Yang, Hee-Man; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2017-02-01

    We propose a new approach to remediate cesium-contaminated clays based on intercalation of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) into clay interlayers. Intercalation of DTAB was found to occur very rapidly and involved exchanging interlayer cations. The reaction yielded efficient cesium desorption (∼97%), including of a large amount of otherwise non-desorbable cesium ions by cation exchange with ammonium ions. In addition, the intercalation of DTAB afforded an expansion of the interlayers, and an enhanced desorption of Cs by cation exchange with ammonium ions even at low concentrations of DTAB. Finally, the residual intercalated surfactants were easily removed by a decomposition reaction with hydrogen peroxide in the presence of Cu 2+ /Fe 2+ catalysts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Chemical bonding and structural ordering of cations in silicate glasses

    International Nuclear Information System (INIS)

    Calas, G.; Cormier, L.; Galoisy, L.; Ramos, A.; Rossano, St.

    1997-01-01

    The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)

  8. Significant role of cationic polymers in drug delivery systems.

    Science.gov (United States)

    Farshbaf, Masoud; Davaran, Soodabeh; Zarebkohan, Amir; Annabi, Nasim; Akbarzadeh, Abolfazl; Salehi, Roya

    2017-11-06

    Cationic polymers are characterized as the macromolecules that possess positive charges, which can be either inherently in the polymer side chains and/or its backbone. Based on their origins, cationic polymers are divided in two category including natural and synthetic, in which the possessed positive charges are as result of primary, secondary or tertiary amine functional groups that could be protonated in particular situations. Cationic polymers have been employed commonly as drug delivery agents due to their superior encapsulation efficacy, enhanced bioavailability, low toxicity and improved release profile. In this paper, we focus on the most prominent examples of cationic polymers which have been revealed to be applicable in drug delivery systems and we also discuss their general synthesis and surface modification methods as well as their controlled release profile in drug delivery.

  9. Interpretation of synchrotron radiation circular dichroism spectra of anionic, cationic, and zwitterionic dialanine forms

    Czech Academy of Sciences Publication Activity Database

    Šebek, Jiří; Gyurcsik, B.; Šebestík, Jaroslav; Kejík, Z.; Bednárová, Lucie; Bouř, Petr

    2007-01-01

    Roč. 111, č. 14 (2007), s. 2750-2760 ISSN 1089-5639 R&D Projects: GA ČR GA203/06/0420; GA AV ČR IAA400550702 Institutional research plan: CEZ:AV0Z40550506 Keywords : synchrotron radiation * circular dichroism * TD DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.918, year: 2007

  10. pH-Sensitive self-propelled motion of oil droplets in the presence of cationic surfactants containing hydrolyzable ester linkages.

    Science.gov (United States)

    Banno, Taisuke; Kuroha, Rie; Toyota, Taro

    2012-01-17

    Self-propelled oil droplets in a nonequilibrium system have drawn much attention as both a primitive type of inanimate chemical machinery and a dynamic model of the origin of life. Here, to create the pH-sensitive self-propelled motion of oil droplets, we synthesized cationic surfactants containing hydrolyzable ester linkages. We found that n-heptyloxybenzaldehyde oil droplets were self-propelled in the presence of ester-containing cationic surfactant. In basic solution prepared with sodium hydroxide, oil droplets moved as molecular aggregates formed on their surface. Moreover, the self-propelled motion in the presence of the hydrolyzable cationic surfactant lasted longer than that in the presence of nonhydrolyzable cationic surfactant. This is probably due to the production of a fatty acid by the hydrolysis of the ester-containing cationic surfactant and the subsequent neutralization of the fatty acid with sodium hydroxide. A complex surfactant was formed in the aqueous solution because of the cation and anion combination. Because such complex formation can induce both a decrease in the interfacial tension of the oil droplet and self-assembly with n-heptyloxybenzaldehyde and lauric acid in the aqueous dispersion, the prolonged movement of the oil droplet may be explained by the increase in heterogeneity of the interfacial tension of the oil droplet triggered by the hydrolysis of the ester-containing surfactant. © 2011 American Chemical Society

  11. Protective effect of divalent cations against aluminum toxicity in soybean

    OpenAIRE

    Silva,Ivo Ribeiro da; Corrêa,Tarcísio Fernando Côrtes; Novais,Roberto Ferreira; Gebrim,Fabrício de Oliveira; Nunes,Flancer Novais; Silva,Eulene Francisco da; Smyth,Thomas Jot

    2008-01-01

    A large proportion of soybean fields in Brazil are currently cultivated in the Cerrado region, where the area planted with this crop is growing considerably every year. Soybean cultivation in acid soils is also increasing worldwide. Since the levels of toxic aluminum (Al) in these acid soils is usually high it is important to understand how cations can reduce Al rhizotoxicity in soybean. In the present study we evaluated the ameliorative effect of nine divalent cations (Ca, Mg, Mn, Sr, Sn, Cu...

  12. Isomerizations of the Nitromethane Radical Cation in the Gas Phase

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Carlsen, Lars; Elbel, Susanne

    1986-01-01

    The concurrent isomerizations of the nitromethane radical cation to its aci-nitromethane and methylnitrite isomers, respectively, has been established based on metastable ion studies and collision activation mass spectrometry. The energy diagram for the ionized nitromethane/aci-nitromethane tauto......The concurrent isomerizations of the nitromethane radical cation to its aci-nitromethane and methylnitrite isomers, respectively, has been established based on metastable ion studies and collision activation mass spectrometry. The energy diagram for the ionized nitromethane...

  13. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    DEFF Research Database (Denmark)

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.

    1998-01-01

    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution...... and the Raman spectrum excited in resonance with the absorption band at 425 nm. The spectrum was interpreted with the help of density functional theory calculations. (C) 1998 Elsevier Science B.V....

  14. Mercury release from deforested soils triggered by base cation enrichment

    International Nuclear Information System (INIS)

    Farella, N.; Lucotte, M.; Davidson, R.; Daigle, S.

    2006-01-01

    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide

  15. Sorption phenomena of modification of clinoptilolite tuffs by surfactant cations.

    Science.gov (United States)

    Rozić, M; Ivanec Sipusić, D; Sekovanić, L; Miljanić, S; Curković, L; Hrenović, J

    2009-03-15

    The sorption of cationic surfactant hexadecyltrimethylammonium (HDTMA) onto the solid/liquid interfaces of different clinoptilolite rich tuffs (CT) is examined. Examined were CT from Serbia with 75% clinoptilolite, CT from Turkey with 70% clinoptilolite, and CT from Croatia with 60% clinoptilolite. The sorption of HDTMA cations increased in the following order: CT from Serbia>CT from Turkey>CT from Croatia. The maximum amounts of sorbed HDTMA cations, normalized with regard to external cation exchange capacities of tuffs, were 1.79, 1.70, and 1.14 for Serbian, Turkish, and Croatian CT. FTIR analysis of samples with the maximum amount of sorbed HDTMA cations showed that HDTMA chains on Serbian CT adopt mainly a stretched all-trans conformation, while at the surfaces of CT from Turkey and Croatia the amount of gauche conformations increased. The zeta potentials of CT samples with the maximum amount of sorbed HDTMA cations and the sorption of benzoate anions on these samples increased in the following order: CT from Turkey>CT from Serbia>CT from Croatia. It can be assumed that on the surface of CT from Turkey iron (hydr)oxide clusters or nanoparticles with positive surface sites are present, due to which the isoelectric point is sifted toward lower and the zeta potential toward higher values. Therefore, the sorption of benzoate anions on modified CT from Turkey is also higher.

  16. Tunable states of interlayer cations in two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Numata, K. [Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Dai, W. [Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071 (China); Hunger, M. [Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart (Germany)

    2014-03-31

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of {sup 23}Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and {sup 23}Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed.

  17. Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

    Energy Technology Data Exchange (ETDEWEB)

    Akbaba, Hasan; Karagöz, Uğur [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey); Selamet, Yusuf [Izmir Institute of Technology, Faculty of Science, Department of Physics, 35433 Izmir (Turkey); Kantarcı, A. Gülten, E-mail: gulten.kantarci@ege.edu.tr [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey)

    2017-03-15

    The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15–17 emu g{sup −1} for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting. - Highlights: • A novel iron oxide nanoparticle synthesis method with in-situ surface coating. • Combining advantages of microemulsions and multiple emulsion methods. • Multiple emulsions were used as microreactors for magnetic nanoparticle synthesis. • Superparamagnetic iron oxide particles synthesized in the core of cationic lipids. • Possible delivery systems for nucleic acids, oil soluble compounds or drugs.

  18. Cationic tungsten-oxo-alkylidene-N-heterocyclic carbene complexes: highly active olefin metathesis catalysts.

    Science.gov (United States)

    Schowner, Roman; Frey, Wolfgang; Buchmeiser, Michael R

    2015-05-20

    The synthesis, structure, and olefin metathesis activity of the first neutral and cationic W-oxo-alkylidene-N-heterocyclic carbene (NHC) catalysts are reported. Neutral W-oxo-alkylidene-NHC catalysts can be prepared in up to 90% isolated yield. Depending on the ligands used, they possess either an octahedral (Oh) or trigonal bipyramidal ligand sphere. They can be activated with excess AlCl3 to form cationic olefin metathesis-active W-complexes; however, these readily convert into neutral chloro-complexes. Well-defined, stable cationic species can be prepared by stoichiometric substitution of one chloro ligand in the parent, neutral W-oxo-alkylidene-NHC complexes with Ag(MeCN)2B(Ar(F))4 or NaB(Ar(F))4; B(Ar(F))4 = B(3,5-(CF3)2-C6H3)4. They are highly active olefin metathesis catalysts, allowing for turnover numbers up to 10,000 in various olefin metathesis reactions including alkenes bearing nitrile, sec-amine, and thioether groups.

  19. Structural Consequences of Anionic Host-Cationic Guest Interactions in a Supramolecular Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, Michael D.; Johnson, Darren W.; Szigethy, Geza; Davis, Anna V.; Teat, Simon J.; Oliver, Allen G.; Bergman, Robert G.; Raymond, Kenneth N.

    2008-07-09

    The molecular structure of the self-assembled supramolecular assembly [M{sub 4}L{sub 6}]{sup 12-} has been explored with different metals (M = Ga{sup III}, Fe{sup III}, Ti{sup IV}) and different encapsulated guests (NEt{sub 4}{sup +}, BnNMe{sub 3}{sup +}, Cp{sub 2}Co{sup +}, Cp*{sub 2}Co{sup +}) by X-ray crystallography. While the identity of the metal ions at the vertices of the M{sub 4}L{sub 6} structure is found to have little effect on the assembly structure, encapsulated guests significantly distort the size and shape of the interior cavity of the assembly. Cations on the exterior of the assembly are found to interact with the assembly through either {pi}-{pi}, cation-{pi}, or CH-{pi} interactions. In some cases, the exterior guests interact with only one assembly, but cations with the ability to form multiple {pi}-{pi} interactions are able to interact with adjacent assemblies in the crystal lattice. The solvent accessible cavity of the assembly is modeled using the rolling probe method and found to range from 253-434 {angstrom}{sup 3}, depending on the encapsulated guest. Based on the volume of the guest and the volume of the cavity, the packing coefficient for each host-guest complex is found to range from 0.47-0.67.

  20. Studies on cationic UV curing of epoxidised palm oil (EPO) for surface coatings

    International Nuclear Information System (INIS)

    Mek Zah Salleh; Mohd Hilmi Mahmood; Wan Rosli Wan Daud; Kumar, R.N.

    2000-01-01

    Epoxidised palm oil (EPO) resin can be cured by ultraviolet (UV) radiation either by radical, cationic or hybrid system. Cationic curing system has been chosen in this study due to the fact that epoxy groups present in EPO can be utilised directly to form crosslinking. Curing was done by means of a 20 cm wide UV IST machine with the conditions of 7.5 A current and 4 m/min conveyor speed. Sulphonium and ferrocenium salts were used as cationic photoinitiator. A formulations study was performed on the selected grades of EPO with other materials. These include types and concentration of photoinitiator, monomers, concentration of EPO and post-cure. The properties of the cured film such as pendulum hardness, percentage of gel content and tensile strength were determined. It was found that triarylsulphonium hexafluorophosphate has a very low solubility in EPO. Addition of vinyl ether monomer to the formulation did not enhance pendulum hardness and gel content of the cured films. It is also found that the post cure temperature has no significant effect on the cured film

  1. Nanoscale cation motion in TaOx, HfOx and TiOx memristive systems

    Science.gov (United States)

    Wedig, Anja; Luebben, Michael; Cho, Deok-Yong; Moors, Marco; Skaja, Katharina; Rana, Vikas; Hasegawa, Tsuyoshi; Adepalli, Kiran K.; Yildiz, Bilge; Waser, Rainer; Valov, Ilia

    2016-01-01

    A detailed understanding of the resistive switching mechanisms that operate in redox-based resistive random-access memories (ReRAM) is key to controlling these memristive devices and formulating appropriate design rules. Based on distinct fundamental switching mechanisms, two types of ReRAM have emerged: electrochemical metallization memories, in which the mobile species is thought to be metal cations, and valence change memories, in which the mobile species is thought to be oxygen anions (or positively charged oxygen vacancies). Here we show, using scanning tunnelling microscopy and supported by potentiodynamic current-voltage measurements, that in three typical valence change memory materials (TaOx, HfOx and TiOx) the host metal cations are mobile in films of 2 nm thickness. The cations can form metallic filaments and participate in the resistive switching process, illustrating that there is a bridge between the electrochemical metallization mechanism and the valence change mechanism. Reset/Set operations are, we suggest, driven by oxidation (passivation) and reduction reactions. For the Ta/Ta2O5 system, a rutile-type TaO2 film is believed to mediate switching, and we show that devices can be switched from a valence change mode to an electrochemical metallization mode by introducing an intermediate layer of amorphous carbon.

  2. Salinity and cationic nature of irrigation water on castor bean cultivation

    Directory of Open Access Journals (Sweden)

    Geovani S. de Lima

    Full Text Available ABSTRACT This study aimed to evaluate the water relations, cell damage percentage and growth of the castor bean cv. ‘BRS Energia’ as a function of salinity and cationic nature of the water used in irrigation. The experiment was conducted in drainage lysimeters under greenhouse conditions in eutrophic Grey Argisol of sandy loam texture. Six combinations of water salinity and cations were studied (S1 - Control; S2 - Na+, S3 - Ca2+, S4 - Na+ + Ca2+; S5 - K+ and S6 - Na+ + Ca2+ + Mg2+, in a randomized block design with four replicates. In the control (S1, plants were irrigated with 0.6 dS m-1 water, whereas the other treatments received 4.5 dS m-1 water, obtained by adding different salts, all in the chloride form. Higher relative water content in the leaf blade of plants irrigated with K+-salinized water associated with leaf succulence are indicative of tolerance of the castor bean cv. ‘BRS Energia’ to salinity. Saline stress negatively affected castor bean growth, regardless of cationic nature of water. Among the ions studied, ‘BRS Energia’ castor bean was more sensitive to the presence of sodium in the irrigation water, in terms of both water relations and leaf succulence.

  3. DFT and ENDOR Study of Bixin Radical Cations and Neutral Radicals on Silica-Alumina.

    Science.gov (United States)

    Tay-Agbozo, Sefadzi S; Krzyaniak, Matthew D; Bowman, Michael K; Street, Shane; Kispert, Lowell D

    2015-06-18

    Bixin, a carotenoid found in annatto (Bixa orellana), is unique among natural carotenoids by being water-soluble. We stabilized free radicals from bixin on the surface of silica-alumina (Si-Al) and characterized them by pulsed electron-nuclear double resonance (ENDOR). DFT calculations of unpaired electron spin distribution for various bixin radicals predict the EPR hyperfine couplings. Least-square fitting of experimental ENDOR spectra by spectra calculated from DFT hyperfine couplings characterized the radicals trapped on Si-Al. DFT predicts that the trans bixin radical cation is more stable than the cis bixin radical cation by 1.26 kcal/mol. This small energy difference is consistent with the 26% trans and 23% cis radical cations in the ENDOR spectrum. The remainder of the ENDOR spectrum is due to several neutral radicals formed by loss of a H(+) ion from the 9, 9', 13, or 13' methyl group, a common occurrence in all water-insoluble carotenoids previously studied. Although carboxyl groups of bixin strongly affect its solubility relative to other natural carotenoids, they do not alter properties of its free radicals based on DFT calculations and EPR measurements which remain similar to typical water-insoluble carotenoids.

  4. [Influence of strength and species of cation on adsorption of norfloxacin in typical soils of China].

    Science.gov (United States)

    Zhang, Jin-qiang; Dong, Yuan-hua

    2007-10-01

    On the basis of OECD Guideline 106, batch sorption methods were employed to reveal the effect of Ca2+ ion strength and different cations (0.01 mol/L solution of NaCl, KCl, NH4LCl, MgCl2, CaCl2, ZnCl2 and AlCl3) on norfloxacin (NOR) sorption-desorption process in four tested soils (Ustic Cambosols, Udic Argosols, Gleyic-Stagnic Anthrosols and Ali-Perudic Ferrosols). Results indicate that sorption coefficient Kf values of NOR gradually decrease to a steady state with the increased concentration of calcium ion in solution. There exists a significantly negative correlation between Ca2+ ion strength and Kf value (p mechanism. Whilst at the zwitterionic form of NOR (pH 6.3-8.4), electrostatic adsorption or dipole moment may control the sorption process. This causes the different sorption behavior of NOR in the four soils. Thus, the calcium ion in solutions is competitively adsorbed to the active sorption sites so as to decrease the NOR sorption amount. Moreover, the different cations result in difference of NOR sorption. Cations of higher valencies are adsorbed more strongly to surface active sorption sites, with the following order: M+ (Na+, K+, NH4+) < M2+ (Ca2+, Mg2+, Zn2+) < M3+ (Al3+).

  5. Supramolecular assembly of Yin(IV) porphyrin cations stabilized by ionic hydrogen bonding interactions

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hwa Jin; Kim, Sung Hyun; Kim, Hee Joon [Dept. of Applied Chemistry, Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2015-09-15

    Our concern for hydrogen-bonded supramolecular assembly with metalloporphyrins led us to exploiting ionic hydrogen bonds, a special class of hydrogen bonds formed between ions and molecules. Because these interactions have up to a third of the strength of covalent bonds, they are expected to be very useful in self-assembly in supramolecular chemistry and molecular crystals. Here we report the preparation and supramolecular assembly of highly charged tin(IV) porphyrin cations stabilized by ionic hydrogen-bonding interactions. We demonstrated that tin(IV) porphyrin cations such as [Sn(OH{sub 2}){sub 2}(T{sup H}PyP)]{sup 6+} can be a useful three-dimensional building block for the construction of porous porphyrin materials. Our X-ray structural analysis revealed that [Sn(OH{sub 2}){sub 2}(T{sup H}PyP)]{sup 6+} cations act as ionic hydrogen-bonding donors possessing electro-deficient six protons from the two axially coordinated aqua ligands and the four equatorial pyridinium peripheral groups.

  6. Potentiating the Anticancer Properties of Bisphosphonates by Nanocomplexation with the Cationic Amphipathic Peptide, RALA.

    Science.gov (United States)

    Massey, Ashley S; Pentlavalli, Sreekanth; Cunningham, Richard; McCrudden, Cian M; McErlean, Emma M; Redpath, Philip; Ali, Ahlam A; Annett, Stephanie; McBride, John W; McCaffrey, Joanne; Robson, Tracy; Migaud, Marie E; McCarthy, Helen O

    2016-04-04

    Bisphosphonates (BPs) are a class of bone resorptive drug with a high affinity for the hydroxyapatite structure of bone matrices that are used for the treatment of osteoporosis. However, clinical application is limited by a common toxicity, BP-related osteonecrosis of the jaw. There is emerging evidence that BPs possess anticancer potential, but exploitation of these antiproliferative properties is limited by their toxicities. We previously reported the utility of a cationic amphipathic fusogenic peptide, RALA, to traffic anionic nucleic acids into various cell types in the form of cationic nanoparticles. We hypothesized that complexation with RALA could similarly be used to conceal a BP's hydroxyapatite affinity, and to enhance bioavailability, thereby improving anticancer efficacy. Incubation of RALA with alendronate, etidronate, risedronate, or zoledronate provoked spontaneous electrostatic formation of cationic nanoparticles that did not exceed 100 nm in diameter and that were stable over a range of temperatures and for up to 6 h. The nanoparticles demonstrated a pH responsiveness, possibly indicative of a conformational change, that could facilitate release of the BP cargo in the endosomal environment. RALA/BP nanoparticles were more potent anticancer agents than their free BP counterparts in assays investigating the viability of PC3 prostate cancer and MDA-MB-231 breast cancer cells. Moreover, RALA complexation potentiated the tumor growth delay activity of alendronate in a PC3 xenograft model of prostate cancer. Taken together, these findings further validate the use of BPs as repurposed anticancer agents.

  7. Efficient gene delivery to human umbilical cord mesenchymal stem cells by cationized Porphyra yezoensis polysaccharide nanoparticles.

    Science.gov (United States)

    Yu, Qingtong; Cao, Jin; Chen, Baoding; Deng, Wenwen; Cao, Xia; Chen, Jingjing; Wang, Yan; Wang, Shicheng; Yu, Jiangnan; Xu, Ximing; Gao, Xiangdong

    2015-01-01

    This study centered on an innovative application of Porphyra yezoensis polysaccharide (PPS) with cationic modification as a safe and efficient nonviral gene vector to deliver a plasmid encoding human Wnt3a (pWnt3a) into human umbilical cord mesenchymal stem cells (HUMSCs). After modification with branched low-molecular-weight (1,200 Da) polyethylenimine, the cationized PPS (CPPS) was combined with pWnt3a to form spherical nanoscale particles (CPPS-pWnt3a nanoparticles). Particle size and distribution indicated that the CPPS-pWnt3a nanoparticles at a CPPS:pWnt3a weight ratio of 40:1 might be a potential candidate for DNA plasmid transfection. A cytotoxicity assay demonstrated that the nanoparticles prepared at a CPPS:pWnt3a weight ratio of 40:1 were nontoxic to HUMSCs compared to those of Lipofectamine 2000 and polyethylenimine (25 kDa). These nanoparticles were further transfected to HUMSCs. Western blotting demonstrated that the nanoparticles (CPPS:pWnt3a weight ratio 40:1) had the greatest transfection efficiency in HUMSCs, which was significantly higher than that of Lipofectamine 2000; however, when the CPPS:pWnt3a weight ratio was increased to 80:1, the nanoparticle-treated group showed no obvious improvement in translation efficiency over Lipofectamine 2000. Therefore, CPPS, a novel cationic polysaccharide derived from P. yezoensis, could be developed into a safe, efficient, nonviral gene vector in a gene-delivery system.

  8. Ultrashort cationic naphthalene-derived self-assembled peptides as antimicrobial nanomaterials.

    Science.gov (United States)

    Laverty, Garry; McCloskey, Alice P; Gilmore, Brendan F; Jones, David S; Zhou, Jie; Xu, Bing

    2014-09-08

    Self-assembling dipeptides conjugated to naphthalene show considerable promise as nanomaterial structures, biomaterials, and drug delivery devices. Biomaterial infections are responsible for high rates of patient mortality and morbidity. The presence of biofilm bacteria, which thrive on implant surfaces, are a huge burden on healthcare budgets, as they are highly resistant to current therapeutic strategies. Ultrashort cationic self-assembled peptides represent a highly innovative and cost-effective strategy to form antibacterial nanomaterials. Lysine conjugated variants display the greatest potency with 2% w/v NapFFKK hydrogels significantly reducing the viable Staphylococcus epidermidis biofilm by 94%. Reducing the size of the R-group methylene chain on cationic moieties resulted in reduction of antibiofilm activity. The primary amine of the protruding R-group tail may not be as readily available to interact with negatively charged bacterial membranes. Cryo-SEM, FTIR, CD spectroscopy, and oscillatory rheology provided evidence of supramolecular hydrogel formation at physiological pH (pH 7.4). Cytotoxicity assays against murine fibroblast (NCTC 929) cell lines confirmed the gels possessed reduced cytotoxicity relative to bacterial cells, with limited hemolysis upon exposure to equine erythrocytes. The results presented in this paper highlight the significant potential of ultrashort cationic naphthalene peptides as future biomaterials.

  9. Design and application of cationic amphiphilic β-cyclodextrin derivatives as gene delivery vectors

    Science.gov (United States)

    Wan, Ning; Huan, Meng-Lei; Ma, Xi-Xi; Jing, Zi-Wei; Zhang, Ya-Xuan; Li, Chen; Zhou, Si-Yuan; Zhang, Bang-Le

    2017-11-01

    The nano self-assembly profiles of amphiphilic gene delivery vectors could improve the density of local cationic head groups to promote their DNA condensation capability and enhance the interaction between cell membrane and hydrophobic tails, thus increasing cellular uptake and gene transfection. In this paper, two series of cationic amphiphilic β-cyclodextrin (β-CD) derivatives were designed and synthesized by using 6-mono-OTs-β-CD (1) as the precursor to construct amphiphilic gene vectors with different building blocks in a selective and controlled manner. The effect of different type and degree of cationic head groups on transfection and the endocytic mechanism of β-CD derivatives/DNA nanocomplexes were also investigated. The results demonstrated that the designed β-cyclodextrin derivatives were able to compact DNA to form stable nanocomplexes and exhibited low cytotoxicity. Among them, PEI-1 with PEI head group showed enhanced transfection activity, significantly higher than commercially available agent PEI25000 especially in the presence of serum, showing potential application prospects in clinical trials. Moreover, the endocytic uptake mechanism involved in the gene transfection of PEI-1 was mainly through caveolae-mediated endocytosis, which could avoid the lysosomal degradation of loaded gene, and had great importance for improving gene transfection activity.

  10. Solid-State Properties of One-Dimensional Metals Based on bis(oxalato)platinate Anions with Divalent Cations

    DEFF Research Database (Denmark)

    Braude, A.; Carneiro, K.; Jacobsen, Claus Schelde

    1987-01-01

    The crystal structures, superstructures, dc conductivity, optical properties, and thermopower of six linear-chain conductors of the type M0.8[Pt(C2O4)2]⋅(M=Ni,Co,Zn,Fe,Mg,Mn), where M is a divalent metal (M=Ni,Co,Zn,Fe,Mg,Mn), have been studied. At high temperatures they form a common orthorhombic...... metallic phase (I) with conductivities of 30–200 (Ω cm)-1 and thermopowers of 5–10 μV/K, with the lattice weakly modulated by the one-dimensional Peierls distortion. Below T1, three compounds (Ni,Co,Zn) form a semiconducting phase (A-II) due to the ordering of the [M(H2O)6]+2 cations. As the cation......-ion lattice and the three-dimensional Peierls distortion, and therefore no charge-density-wave state is formed. The influence of competing interactions is briefly discussed....

  11. Novel Reactivity Of The Cationic Complex

    International Nuclear Information System (INIS)

    Wang, J.; Dash, A.K.; Eisen, AM.; Berthet, J.C.; Ephritikhine, M.

    2002-01-01

    The catalytic chemistry of electrophilic d 0 /f organometallic complexes is nowadays under intense investigation, reaching a high level of sophistication. General aspects concerning these complexes are concentrated for most studies to the functionalization of unsaturated organic molecules. To cite an instance, the actinide-promoted oligomerization of terminal alkynes is of essential present concern since it may introduce to a diversity of organic enynes and oligoacetylene products that are valuable synthons for the synthesis of natural products. Enynes are the simplest oligomerization products of alkynes. We have demonstrated that organoactinides complexes of the type [Cp* 2 AnMe 2 AnMe 2 ] (Cp* = C 5 Me 5 ; An = U, Th) are active catalysts for the linear oligomerization of terminal alkynes and the extent of oligomerization was found to be strongly dependent on the electronic and steric properties of the alkyne substituents. Bulky alkynes were reacted with high regioselectivity toward dimer and/or trimers whereas for non-bulky alkynes, these compounds were transformed into oligomers with a total deficiency of regioselectivity. The addition of primary amines to the catalytic cycle, for An = Th, granted the chemoselective formation of dimers, chemoselectively, whereas for An = U, this control was not succeeded. In distinction to the neutral organoactinide complexes, homogeneous cationic d 0 /f n actinide complexes have been used as in the homogeneous polymerization of olefins as extremely active catalysts. Hence, the catalytic alkyne oligomerization is a opportune route to explore insertions and σ-bond metathesis reactivity of complexes. We have recently shown that the reaction of terminal alkynes (RC≡CH), promoted by [(Et 2 N) 3 U][BPh 4 ], in toluene, produces efficiently mostly the gem dimers (for R = Me, i Pr and n Bu) as the major products, whereas for bulky alkynes (R = t MS or t Bu) small amounts of the cis dimer was concomitantly obtained. A plausible

  12. Aquatic toxicity and biodegradability of advanced cationic surfactant APA-22 compatible with the aquatic environment.

    Science.gov (United States)

    Yamane, Masayuki; Toyo, Takamasa; Inoue, Katsuhisa; Sakai, Takaya; Kaneko, Youhei; Nishiyama, Naohiro

    2008-01-01

    Cationic surfactant is a chemical substance used in hair conditioner, fabric softener and other household products. By investigating the relationship between the aquatic toxicity and the chemical structures of two types of mono alkyl cationic surfactants, alkyl trimethylammonium salts and alkyl dimethylamine salts, we have found that the C22 alkyl chain length is effective to reduce the toxicity. Besides, we have recognized that the amidopropyl functional group contributes to the enhanced biodegradability by investigating the biodegradation trend of (alkylamidopropyl)dimethylamine salt (alkyl chain length: C18). Based on these findings, we have developed mono alkyl cationic surfactant called APA-22, N-[3-(dimethylamino)propyl]docosanamide salt. APA-22 is formed by the C22 alkyl chain, amidopropyl functional group and di-methyltertiary amine group. We evaluated the aerobic and anaerobic biodegradability of APA-22 by two standard methods (OECD Test Guideline 301B and ECETOC technical document No.28) and found that this substance was degraded rapidly in both conditions. The toxicity to algae, invertebrate and fish of this substance are evaluated by using OECD Test Guideline 201, 202 and 203, respectively. All acute toxicity values are >1 mg/L, which indicates that environmental toxicity of this substance is relatively less toxic to aquatic organism. In addition, we estimated the biodegradation pathway of APA-22 and observed the complete disappearance of APA-22 and its intermediates during the test periods. Based on the environmental data provided above, we concluded that APA22 is more compatible with the aquatic environment compared to other cationic surfactants with mono long alkyl chain.

  13. 9-phenanthrol inhibits human TRPM4 but not TRPM5 cationic channels.

    Science.gov (United States)

    Grand, T; Demion, M; Norez, C; Mettey, Y; Launay, P; Becq, F; Bois, P; Guinamard, R

    2008-04-01

    TRPM4 and TRPM5 are calcium-activated non-selective cation channels with almost identical characteristics. TRPM4 is detected in several tissues including heart, kidney, brainstem, cerebral artery and immune system whereas TRPM5 expression is more restricted. Determination of their roles in physiological processes requires specific pharmacological tools. TRPM4 is inhibited by glibenclamide, a modulator of ATP binding cassette proteins (ABC transporters), such as the cystic fibrosis transmembrane conductance regulator (CFTR). We took advantage of this similarity to investigate the effect of hydroxytricyclic compounds shown to modulate ABC transporters, on TRPM4 and TRPM5. Experiments were conducted using HEK-293 cells permanently transfected to express human TRPM4 or TRPM5. Currents were recorded using the whole-cell and inside-out variants of the patch-clamp technique. The CFTR channel activator benzo[c]quinolizinium MPB-104 inhibited TRPM4 current with an IC(50) in the range of 2 x 10(-5) M, with no effect on single-channel conductance. In addition, 9-phenanthrol, lacking the chemical groups necessary for CFTR activation, also reversibly inhibited TRPM4 with a similar IC(50). Channel inhibition was voltage independent. The IC(50) determined in the whole-cell and inside-out experiments were similar, suggesting a direct effect of the molecule. However, 9-phenanthrol was ineffective on TRPM5, the most closely related channel within the TRP protein family. We identify 9-phenanthrol as a TRPM4 inhibitor, without effects on TRPM5. It could be valuable in investigating the physiological functions of TRPM4, as distinct from those of TRPM5.

  14. Impact of non-selective fungicides on the growth and production of ochratoxin A by Aspergillus ochraceus and A. carbonarius in barley-based medium.

    Science.gov (United States)

    Mateo, Eva M; Valle-Algarra, F M; Mateo-Castro, R; Jimenez, M

    2011-01-01

    The aim of this study was to assess the influence of the non-selective fungicides mancozeb, copper oxychloride, and sulfur on the growth and capability for producing ochratoxin A (OTA) of ochratoxigenic isolates of Aspergillus carbonarius and A. ochraceus in barley-based medium. Lag phases and growth rates were determined for each fungicide at different doses, at 15°C and 25°C and at 0.97 a(w). Mancozeb at 40 mg l(-1 )inhibited fungal growth and provided lag phases >24 days at 10-20 mg l(-1) and 15°C. OTA was observed only at 25°C and doses Sulfur was inhibitory or provided large lag phases at 5-8 g l(-1) (at 15°C) while at 25°C growth took place even at 8 g l(-1), although OTA levels were low or undetectable. The antifungal activity decreased in the order mancozeb > copper oxychloride > sulfur, and was lower at 25°C than at 15°C. OTA accumulation was affected by the type of fungicide, dose, temperature and time. The efficacy of these fungicides on the growth of A. carbonarius and A. ochraceus and OTA production in barley-based medium is assessed for the first time.

  15. Endoplasmic reticulum turnover: ER-phagy and other flavors in selective and non-selective ER clearance [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Ilaria Fregno

    2018-04-01

    Full Text Available The endoplasmic reticulum (ER is a highly dynamic organelle in eukaryotic cells. It is deputed to lipid and protein biosynthesis, calcium storage, and the detoxification of various exogenous and endogenous harmful compounds. ER activity and size must be adapted rapidly to environmental and developmental conditions or biosynthetic demand. This is achieved on induction of thoroughly studied transcriptional/translational programs defined as “unfolded protein responses” that increase the ER volume and the expression of ER-resident proteins regulating the numerous ER functions. Less understood are the lysosomal catabolic processes that maintain ER size at steady state, that prevent excessive ER expansion during ER stresses, or that ensure return to physiologic ER size during recovery from ER stresses. These catabolic processes may also be activated to remove ER subdomains where proteasome-resistant misfolded proteins or damaged lipids have been segregated. Insights into these catabolic mechanisms have only recently emerged with the identification of so-called ER-phagy receptors, which label specific ER subdomains for selective lysosomal delivery for clearance. Here, in eight chapters and one addendum, we comment on recent advances in ER turnover pathways induced by ER stress, nutrient deprivation, misfolded proteins, and live bacteria. We highlight the role of yeast (Atg39 and Atg40 and mammalian (FAM134B, SEC62, RTN3, and CCPG1 ER-phagy receptors and of autophagy genes in selective and non-selective catabolic processes that regulate cellular proteostasis by controlling ER size, turnover, and function.

  16. Increased localized delivery of piroxicam by cationic nanoparticles after intra-articular injection

    Directory of Open Access Journals (Sweden)

    Kim SR

    2016-11-01

    Full Text Available Sung Rae Kim,1 Myoung Jin Ho,2 Sang Hyun Kim,1 Ha Ra Cho,2 Han Sol Kim,2 Yong Seok Choi,2 Young Wook Choi,1 Myung Joo Kang2 1Division of Pharmaceutical Sciences, College of Pharmacy, Chung-Ang University, Seoul, 2College of Pharmacy, Dankook University, Cheonan, Chungnam, South Korea Abstract: Piroxicam (PRX, a potent nonsteroidal anti-inflammatory drug, is prescribed to relieve postoperative and/or chronic joint pain. However, its oral administration often results in serious gastrointestinal adverse effects including duodenal ulceration. Thus, a novel cationic nanoparticle (NP was explored to minimize the systemic exposure and increase the retention time of PRX in the joint after intra-articular (IA injection, by forming micrometer-sized electrostatic clusters with endogenous hyaluronic acid (HA in the synovial cavity. PRX-loaded NPs consisting of poly(lactic-co-glycolic acid, Eudragit RL, and polyvinyl alcohol were constructed with the following characteristics: particle size of 220 nm, zeta potential of 11.5 mV in phosphate-buffered saline, and loading amount of 4.0% (w/w of PRX. In optical and hyperspectral observations, the cationic NPs formed more than 50 µm-sized aggregates with HA, which was larger than the intercellular gaps between synoviocytes. In an in vivo pharmacokinetic study in rats, area under the plasma concentration–time curve (AUC0–24 h and maximum plasma concentration (Cmax of PRX after IA injection of the cationic NPs were <70% (P<0.05 and 60% (P<0.05, respectively, compared to those obtained from drug solution. Moreover, the drug concentration in joint tissue 24 h after dosing with the cationic NPs was 3.2-fold (P<0.05 and 1.8-fold (P<0.05 higher than that from drug solution and neutrally charged NPs, respectively. Therefore, we recommend the IA cationic NP therapy as an effective alternative to traditional oral therapy with PRX, as it increases drug retention selectively in the joint. Keywords: piroxicam

  17. Relative abundances of primary ion radicals in γ-irradiated DNA: Cytosine vs thymine anions and guanine vs adenine cations

    International Nuclear Information System (INIS)

    Sevilla, M.D.; Becker, D.; Yan, Mengyao; Summerfield, S.R.

    1991-01-01

    An ESR study of the relative distribution of ion radicals formed in DNA equilibrated with D 2 O and γ-irradiated at 77 K is presented. The ESR spectra of irradiated DNA and polynucleotides (poly[dG]·poly[dC] and poly[dAdT]·poly[dAdT]) were obtained and employed in a computer-assisted analysis for the individual ion-radical distribution. Analysis of spectra as a function of power allowed the separation of the spectra of the pyrimidine anions (T sm-bullet- , C sm-bullet- ) from the spectra of the purine cations (G sm-bullet+ , A sm-bullet+ ). The spectra of the mononucleotide ion radicals, dCMP sm-bullet- , dTMP sm-bullet- , dGMP sm-bullet+ , and dAMP sm-bullet+ , were produced in 8 M LiCl glasses. In addition, the spectra of the ion radicals of all of the mononucleotide ion radicals except dAMP + were simulated by using hyperfine and g tensors from the literature. Basis spectra derived from (1) power saturation experiments, (2) polynucleotide and mononucleotide spectra, (3) spectra of mononucleotides alone, and (4) anisotropic simulations were used to fit the spectra of DNA by use of a linear least-squares analysis. Each of the four separate analyses confirms that the cytosine anion dominates the spectra of DNA at 100 K. Three analyses included the cationic composition, and they strongly favor the guanine cation over the adenine cation. An average of the authors results gives the DNA ion radicals' relative to abundances as ca. 77% C sm-bullet- , 23% T sm-bullet- for the anions and >90% G sm-bullet+ for the cations about equal amounts of anions and cations are present. No difference in results is found for DNA irradiated in frozen D 2 O solutions or simply exchanged at 100% D 2 O humidity

  18. Cation Exchange in the Presence of Oil in Porous Media.

    Science.gov (United States)

    Farajzadeh, R; Guo, H; van Winden, J; Bruining, J

    2017-04-20

    Cation exchange is an interfacial process during which cations on a clay surface are replaced by other cations. This study investigates the effect of oil type and composition on cation exchange on rock surfaces, relevant for a variety of oil-recovery processes. We perform experiments in which brine with a different composition than that of the in situ brine is injected into cores with and without remaining oil saturation. The cation-exchange capacity (CEC) of the rocks was calculated using PHREEQC software (coupled to a multipurpose transport simulator) with the ionic composition of the effluent histories as input parameters. We observe that in the presence of crude oil, ion exchange is a kinetically controlled process and its rate depends on residence time of the oil in the pore, the temperature, and kinetic rate of adsorption of the polar groups on the rock surface. The cation-exchange process occurs in two stages during two phase flow in porous media. Initially, the charged sites of the internal surface of the clays establish a new equilibrium by exchanging cations with the aqueous phase. At later stages, the components of the aqueous and oleic phases compete for the charged sites on the external surface or edges of the clays. When there is sufficient time for crude oil to interact with the rock (i.e., when the core is aged with crude oil), a fraction of the charged sites are neutralized by the charged components stemming from crude oil. Moreover, the positively charged calcite and dolomite surfaces (at the prevailing pH environment of our experiments) are covered with the negatively charged components of the crude oil and therefore less mineral dissolution takes place when oil is present in porous media.

  19. Quantitative electrochromatography of uranium and platinum on papers impregnated with thorium and antimony based cation exchanger

    International Nuclear Information System (INIS)

    Misra, A.K.

    1992-01-01

    Electrochromatography of 32 metal ions have been studied on papers impregnated with thorium antimonate cation exchanger in aq. organic acids, aq. nitric acid as well as in EDTA buffers. On the basis of differential migration which depends on the ion exchange properties of thorium antimonate and nature of complexes formed with the electrolytes, some useful qualitative and quantitative separations of synthetic mixtures of metal ions have been achieved. The effect of some other physical parameter has also been discussed. Quantitative separation of platinum and uranium has been developed. (author). 13 refs., 2 figs., 5 tabs

  20. Comparison of functional properties of the Ca2+-activated cation channels TRPM4 and TRPM5 from mice.

    Science.gov (United States)

    Ullrich, Nina D; Voets, Thomas; Prenen, Jean; Vennekens, Rudi; Talavera, Karel; Droogmans, Guy; Nilius, Bernd

    2005-03-01

    Non-selective cation (NSC) channels activated by intracellular Ca2+ ([Ca2+]i) play an important role in Ca2+ signaling and membrane excitability in many cell types. TRPM4 and TRPM5, two Ca2+-activated cation channels of the TRP superfamily, are potential molecular correlates of NSC channels. We compared the functional properties of mouse TRPM4 and TRPM5 heterologously expressed in HEK 293 cells. Dialyzing cells with different Ca2+ concentrations revealed a difference in Ca2+ sensitivity between TRPM4 and TRPM5, with EC50 values of 20.2+/-4.0 microM and 0.70+/-0.1 microM, respectively. Similarly, TRPM5 activated at lower Ca2+ concentration than TRPM4 when [Ca2+]i was raised by UV uncaging of the Ca2+-cage DMNP-EDTA. Current amplitudes of TRPM4 and TRPM5 were not correlated to the rate of changes in [Ca2+]i. The Ca2+ sensitivity of both channels was strongly reduced in inside-out patches, resulting in approximately 10-30 times higher EC50 values than under whole-cell conditions. Currents through TRPM4 and TRPM5 deactivated at negative and activated at positive potentials with similar kinetics. Both channels were equally sensitive to block by intracellular spermine. TRPM4 displayed a 10-fold higher affinity for block by flufenamic acid. Importantly, ATP4- blocked TRPM4 with high affinity (IC50 of 0.8+/-0.1 microM), whereas TRPM5 is insensitive to ATP4- at concentrations up to 1 mM.

  1. Ion exchange of some transition metal cations on hydrated titanium dioxide in aqueous ammonia solutions

    International Nuclear Information System (INIS)

    Bilewicz, A.; Narbutt, J.; Dybczynski, R.

    1992-01-01

    The adsorption of transition metal cations on hydrated titanium dioxide in complexing ammonia and amine solutions has been studied as a function of ammonia (amine) concentration. The relationships between the distribution coefficients and ammonia concentration as well as the effects of various amines on sorption of transition metals indicate that a coordinate bond is formed between the metal ions and the hydroxy groups of the sorbent. The distribution coefficients of silver(I) and cobalt(II), which form strong ammonia complexes in aqueous solutions, decrease with increasing concentration of ammonia already at concentrations exceeding 10 -3 *mol*dm -3 . Cations of zinc, manganese and mercury which form much weaker ammonia complexes do not exhibit any effect of ammonia concentration in the whole range investigated. In the case of sorption of macroamounts of ammonia or amine complexes of silver, the molecular sieve effect plays an important role. The differences in the affinity of hydrated titanium dioxide for ammonia solvates of various transition metal ions can serve as a tool for effective separation of these ions in ammonia solutions. (author) 10 refs.; 4 figs.; 1 tab

  2. Heteropoly acids triggered self-assembly of cationic peptides into photo- and electro-chromic gels.

    Science.gov (United States)

    Li, Jingfang; Xu, Jing; Li, Xiaodong; Gao, Wenmei; Wang, Liyan; Wu, Lixin; Lee, Myongsoo; Li, Wen

    2016-07-07

    A series of cationic peptides with alternating lysines and hydrophobic residues were designed and synthesized. These kinds of short peptides with protonated lysines can complex with anionic heteropoly acids (HPAs) to form a stable gel in water/ethanol mixed solution. Circular dichroism spectroscopy showed that the short peptides adopted a mixed conformation (β-sheet and random-coil) within the gel matrix. Scanning and transmission electron microscopy revealed that the heteropoly acids, acting as nanosized cross-linkers, first initiated the self-assembly of the cationic peptides into spherical nanostructures. Then these nanospheres accumulated with each other through hydrogen bonds and hydrophobic interactions to form large sheet-like assemblies, which further interconnected with each other forming continuous 3D network structures. Fourier-transform infrared spectroscopy showed that the structural integrity of the HPAs was maintained during the gelation process. The resultant hybrid gels showed reversible photo- and elecrtro-chromic properties. X-ray photoelectron spectroscopy revealed that the hybrid gels, capable of persistent and reversible changes of their colour, are attributed to the intervalence charge-transfer transition of the HPAs. Reversible information writing and erasing were demonstrated through a repeated photo-lithograph or electric stimuli without significant loss of the gel performance.

  3. Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Makowski, Mariusz; Chmurzynski, Lech

    2007-01-01

    Hydrogen bond OHO-type bridges formed between six substituted 4-halo (Cl, Br) pyridine N-oxide systems and their simple cations have been investigated by using the potentiometric titration method. The formation constants of these complexes (expressed as lgK BHB + ) have been determined in two non-aqueous aprotic solvents with different polarity, i.e., acetone (AC) and acetonitrile (AN). It has been observed that tri- and tetra-substituted pyridine N-oxides [B] and their cationic acids [BH + ] form stable homocomplexed cations [BHB + ] stabilized by O...H...O bridges in both solvents used. It has been found that the most stable homocomplexed system is formed by 3,5-dimethyl-4-chloropyridine N-oxide (3,5Me 2 4ClPyO). The lgK BHB + values for this compound in acetone and acetonitrile are 3.15 and 2.82, respectively. Furthermore, by using ab initio methods at the RHF and MP2 levels utilizing the Gaussian 6-31++G ** basis set, the energies of formation of the homocomplexed cations and Gibbs free energies have been determined in vacuo. The calculated energy parameters in vacuo have been compared with the cationic homoconjugation constants determined potentiometrically in acetone and acetonitrile to establish a correlation between these magnitudes. Additionally, the results of potentiometric measurements have been used to determine the acidity constants of the conjugate acids of N-oxides

  4. Spectroscopic Identification of the Carbyne Hydride Structure of the Dehydrogenation Product of Methane Activation by Osmium Cations.

    Science.gov (United States)

    Armentrout, P B; Kuijpers, Stach E J; Lushchikova, Olga V; Hightower, Randy L; Boles, Georgia C; Bakker, Joost M

    2018-04-09

    The present work explores the structures of species formed by dehydrogenation of methane (CH 4 ) and perdeuterated methane (CD 4 ) by the 5d transition metal cation osmium (Os + ). Using infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory (DFT), the structures of the [Os,C,2H] + and [Os,C,2D] + products are explored. This study complements previous work on the related species formed by dehydrogenation of methane by four other 5d transition metal cations (M + = Ta + , W + , Ir + , and Pt + ). Osmium cations are formed in a laser ablation source, react with methane pulsed into a reaction channel downstream, and the resulting products spectroscopically characterized through photofragmentation using the Free-Electron Laser for IntraCavity Experiments (FELICE) in the 300-1800 cm -1 range. Photofragmentation was monitored by the loss of H 2 /D 2 . Comparison of the experimental spectra and DFT calculated spectra leads to identification of the ground state carbyne hydride, HOsCH + ( 2 A') as the species formed, as previously postulated theoretically. Further, a full description of the systematic spectroscopic shifts observed for deuterium labeling of these complexes, some of the smallest systems to be studied using IRMPD action spectroscopy, is achieved. A full rotational contour analysis explains the observed linewidths as well as the observation of doublet structures in several bands, consistent with previous observations for HIrCH + ( 2 A'). Graphical Abstract ᅟ.

  5. Water quality monitoring system for determination of ionic nutrients by ion-exclusion chromatography with spectrophotometric detection on cation- and anion-exchange resin columns using water eluent.

    Science.gov (United States)

    Kozaki, Daisuke; Nakatani, Nobutake; Mori, Masanobu; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

    2012-07-01

    A unified ion-exclusion chromatography (IEC) system for monitoring anionic and cationic nutrients like NH4+, NO2-, NO3-, phosphate ion, silicate ion and HCO3- was developed and applied to several environmental waters. The IEC system consisted of four IEC methodologies, including the IEC with ultraviolet (UV) form connected with detection at 210 nm for determining NH4+ on anion-exchange separation column in OH anion-exchange UV-conversion column in I- form in tandem, the IEC with UV-detection at 210 nm for determining simultaneously NO3- and NO3- on cation-exchange separation column in H+ form, the IEC with UV-detection at 210 nm for determining HCO3- on cation-exchange separation column in H+ form connected with anion-exchange UV-conversion column in I- form in tandem, and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H+ form. These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients. Using this sequential water quality monitoring system, the analytical performances such as calibration linearity, reproducibility, detection limit and recovery were also tested under the optimized chromatographic conditions. This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters.

  6. Contributors Form

    Directory of Open Access Journals (Sweden)

    Chief Editor

    2016-06-01

    to produce preprints or reprints and translate into languages other than English for sale or free distribution; and 4 the right to republish the work in a collection of articles in any other mechanical or electronic format. We give the rights to the corresponding author to make necessary changes as per the request of the journal, do the rest of the correspondence on our behalf and he/she will act as the guarantor for the manuscript on our behalf. All persons who have made substantial contributions to the work reported in the manuscript, but who are not contributors, are named in the Acknowledgment and have given me/us their written permission to be named. If I/we do not include an Acknowledgment that means I/we have not received substantial contributions from non-contributors and no contributor has been omitted.S NoAuthors' NamesContribution (IJCME Guidelines{1 substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; 2 drafting the article or revising it critically for important intellectual content; and 3 final approval of the version to be published. Authors should meet conditions 1, 2, and 3}.SignatureDate                              Note: All the authors are required to sign independently in this form in the sequence given above. In case an author has left the institution/country and whose whereabouts are not known, the senior author may sign on his/her behalf taking the responsibility.No addition/deletion/ or any change in the sequence of the authorship will be permissible at a later stage, without valid reasons and permission of the Editor.If the authorship is contested at any stage, the article will be either returned or will not be processed for publication till the issue is solved.Maximum up to 4 authors for short communication and up to 6 authors for original article.

  7. THERMODYNAMICS OF ETHANOLAMMONIUM CATIONES DISSOCIATION IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R. E. Khoma

    2017-03-01

    Full Text Available The literature data on the thermodynamics of ethanolamines onium cations dissociation have been systematized and generalized. The correlation between these cations dissociation thermodynamic functions (DH and DS and physicochemical properties (Tmp., Tbp, Pp, lgPow et al. has been revealed. There was a correlation between lipophilicity determined experimentally and calculated by QSAR. For monoethanolammonium, diethanolammonium, and their N-methyl and N-ethyl derivatives it was found dissociation thermodynamic functions to depend on bases lgPow. Acid-base dissociation of TRIS and triethanolamine onium cations does not correspond to said relationship because TRIS (primary amine, TEA (tertiary amine act differently on aqueous solutions of SO2. TEA, unlike MEA, DEA and MMEA, has a salting out effect towards sulfur dioxide because of competing hydration that promotes sulfite «onium» salts hydrolysis. TRIS promotes S(IV → S(VI sulphooxidation, in contrast to another ethanolamines. Enthalpy–enthropy compensation with isothermodynamic temperature 303 K has been recorded. The revealed correlations may be useful in developing of procedures for air sanitary cleaning from acidic gases; chemisorbents immobilized for gas and ion exchange chromatography; potentiometric methods for fluorocomplex acids determinations. The use of monoethanolamine is most promising to obtain chemisorbents because the thermodynamic functions of its onium cation acid-base dissociation are least dependent on temperature compared to other etanolammonium cations.

  8. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    J. Aouam sous le nom de schistes Mokattam et schistes cloisonnés. c- Le dévonien : Les dépôts du Dévonien inférieur sont constitués d'argilites indiquant une sédimentation calme de plate forme externe, qui va s'enrichir en nodules et calcaire. Cette sédimentation carbonatée va subir une perturbation, puisqu'au Dévonien ...

  9. Effect of selective and non-selective serotonin receptor activation on L-DOPA-induced therapeutic efficacy and dyskinesia in parkinsonian rats.

    Science.gov (United States)

    Tronci, E; Fidalgo, C; Stancampiano, R; Carta, M

    2015-10-01

    Selective activation of 5-HT1 receptors has been shown to produce near to full suppression of L-DOPA-induced dyskinesia (LID) in animal models of Parkinson's disease; however, a reduction of the therapeutic effect of L-DOPA has been reported in several studies. Conversely, we recently found that increasing the serotonergic tone with chronic administration of the serotonin precursor 5-hydroxy-tryptophan (5-HTP) can reduce LID in 6-OHDA-lesioned rats, without affecting L-DOPA efficacy. To directly compare the effects of selective versus non-selective serotonin receptor activation, here we first tested different acute doses of the 5-HT1A/1B receptor agonist eltoprazine and 5-HTP on LID in order to identify doses of the individual compounds showing similar anti-dyskinetic efficacy in L-DOPA-primed dyskinetic rats. About 50% reduction of LID was observed with 0.1 mg/kg and 24 mg/kg of eltoprazine and 5-HTP, respectively; we then compared the effect of the two drugs, individually and in combination, on L-DOPA-induced stepping test in L-DOPA-naïve parkinsonian animals and LID over three weeks of L-DOPA treatment. Results showed that eltoprazine induced significant worsening of L-DOPA-mediated performance in the stepping test, while 5-HTP did not. Interestingly, combination of 5-HTP with eltoprazine prevented the reduction in the forelimb use induced by eltoprazine. Moreover, 5-HTP and eltoprazine given individually showed similar efficacy also upon chronic treatment, and had additive effect in dampening the appearance of LID when given in combination. Finally, chronic administration of eltoprazine and/or 5-HTP did not affect striatal serotonin innervation, compared to l-DOPA alone, as measured by serotonin transporter expression. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. COMPARISON OF SELECTIVE AND NON SELECTIVE CYCLO-OXYGENASE 2 INHIBITORS IN EXPERIMENTAL COLITIS EXACERBATION: role of leukotriene B4 and superoxide dismutase

    Directory of Open Access Journals (Sweden)

    José Wander BREGANÓ

    2014-09-01

    Full Text Available Context Nonsteroidal anti-inflammatory drugs are considered one of the most important causes of reactivation of inflammatory bowel disease. With regard to selective cyclo-oxygenase 2 inhibitors, the results are controversial in experimental colitis as well as in human studies. Objectives The aim this study is to compare nonsteroidal anti-inflammatory drugs effects, selective and non selective cyclo-oxygenase 2 inhibitors, in experimental colitis and contribute to the understanding of the mechanisms which nonsteroidal anti-inflammatory drugs provoke colitis exacerbation. Methods Six groups of rats: without colitis, with colitis, and colitis treated with celecoxib, ketoprofen, indometacin or diclofenac. Survival rates, hemoglobin, plasmatic albumin, colonic tissue of interleukin-1ß, interleukin-6, tumor necrosis factor alpha, prostaglandin E2, catalase, superoxide dismutase, thiobarbituric acid-reactive substances, chemiluminescence induced by tert-butil hydroperoxides, and tissue and plasmatic leukotriene B4 were determined. Results The groups treated with diclofenac or indometacin presented lower survival rates, hemoglobin and albumin, higher tissue and plasmatic leukotriene B4 and tissue superoxide dismutase than the group treated with celecoxib. Ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib, concerning to survival rate and albumin. The groups without colitis, with colitis and with colitis treated with celecoxib showed leukotriene B4 and superoxide dismutase lower levels than the groups treated with nonselective cyclo-oxygenase 2 inhibitors. Conclusions Diclofenac and indometacin presented the highest degree of induced colitis exacerbation with nonsteroidal anti-inflammatory drugs, celecoxib did not show colitis exacerbation, and ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib. These results suggest that leukotriene B4 and superoxide dismutase can be

  11. Homogeneous non-selective and slice-selective parallel-transmit excitations at 7 Tesla with universal pulses: A validation study on two commercial RF coils.

    Directory of Open Access Journals (Sweden)

    Vincent Gras

    Full Text Available Parallel transmission (pTx technology, despite its great potential to mitigate the transmit field inhomogeneity problem in magnetic resonance imaging at ultra-high field (UHF, suffers from a cumbersome calibration procedure, thereby making the approach problematic for routine use. The purpose of this work is to demonstrate on two different 7T systems respectively equipped with 8-transmit-channel RF coils from two different suppliers (Rapid-Biomed and Nova Medical, the benefit of so-called universal pulses (UP, optimized to produce uniform excitations in the brain in a population of adults and making unnecessary the calibration procedures mentioned above. Non-selective and slice-selective UPs were designed to return homogeneous excitation profiles throughout the brain simultaneously on a group of ten subjects, which then were subsequently tested on ten additional volunteers in magnetization prepared rapid gradient echo (MPRAGE and multi-slice gradient echo (2D GRE protocols. The results were additionally compared experimentally with the standard non-pTx circularly-polarized (CP mode, and in simulation with subject-specific tailored excitations. For both pulse types and both coils, the UP mode returned a better signal and contrast homogeneity than the CP mode. Retrospective analysis of the flip angle (FA suggests that the FA deviation from the nominal FA on average over a healthy adult population does not exceed 11% with the calibration-free parallel-transmit pulses whereas it goes beyond 25% with the CP mode. As a result the universal pulses designed in this work confirm their relevance in 3D and 2D protocols with commercially available equipment. Plug-and-play pTx implementations henceforth become accessible to exploit with more flexibility the potential of UHF for brain imaging.

  12. Reducing the Risk of Cardiovascular Diseases in Non-selected Outpatients With Schizophrenia: A 30-Month Program Conducted in a Real-life Setting.

    Science.gov (United States)

    Hjorth, Peter; Juel, Anette; Hansen, Mette Vinther; Madsen, Nikolaj Juul; Viuff, Anne Grethe; Munk-Jørgensen, Povl

    2017-12-01

    The most common cause of premature death in people with schizophrenia is cardiovascular disease, partially explained by an unhealthy lifestyle, smoking, poor diet and sedentary behavior. We aimed to reduce cardiovascular risk factors. Naturalistic follow-up study with 54 long-term-treated non-selected outpatients with schizophrenia. The 30-month program consisted of individual guidance, group sessions and normal treatment and care offered in our clinic. On average, the participating women reduced their waist circumference by 11.4cm (P=0.037), whereas the participating men increased their waist circumference by 3.3cm (P=0.590). Patients' consumption of fast food was reduced from 1.2 to 0.8 times/week (P=0.016), just as their consumption of soft drinks was reduced from 0.7 to 0.1l/day (P=0.006). Their consumption of coffee increased from 1.6 to 2.5 cups/day (P=0.086). The time women spent on light physical activity increased from 134 to 469min/week (P=0.055). The number of daily cigarettes smoked was reduced by 25.7% for all smokers. Our program showed that it is possible for women but not for men to reduce their risk factors for developing cardiovascular disease. The program is manageable in most outpatient clinics and can be performed by nursing staff interested in physical health with support from and in cooperation with medical doctors, psychiatrist and leaders/managers. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Non-enhanced 3D MR angiography of the lower extremity using ECG-gated TSE imaging with non-selective refocusing pulses. Initial experience

    International Nuclear Information System (INIS)

    Lanzman, R.S.; Blondin, D.; Orzechowski, D.; Scherer, A.; Moedder, U.; Kroepil, P.; Godehardt, E.

    2010-01-01

    Purpose: To evaluate non-enhanced 3D MR angiography using turbo spin echo (TSE) imaging with non-selective refocusing pulses (NATIVE SPACE MRA) for the visualization of the arteries of the lower extremity. Materials and Methods: Three-station imaging (iliac arteries, femoral arteries, arteries of the lower leg) was performed in 8 healthy volunteers and 3 patients with peripheral artery disease (PAD) using a 1.5 T MR scanner. In 8 healthy volunteers, 4 different acquisition schemes were performed with the following imaging parameters: S 1: acquisition with every heartbeat (RR = 1), spoiler gradient of 25 % (SG = 25 %); S 2: RR = 1, SG = 0 %; S 3: RR = 2, SG = 25 %; S 4: RR = 2, SG = 0 %. The subjective image quality on a 4-point-scale (4 = excellent to 1 = not diagnostic) and relative SNR were assessed. In 3 patients with peripheral artery disease (PAD), SPACE MRA was performed for assessment of stenosis. Results: The mean subjective image quality was significantly lower for the iliac arteries compared to the femoral arteries and arteries of the lower leg (p < 0.0001). The subjective image quality for acquisition scheme S 1 was significantly lower than the image quality for S 3 and S 4 for the iliac arteries (p < 0.01), while the subjective image quality for acquisition scheme S 2 was significantly lower than S 3 and S 4 for the femoral arteries and the arteries of the lower leg (p < 0.01). The relative SNR was significantly higher for acquisition schemes S 3 and S 4 as compared to S 1 and S 2 (p < 0.0001) for all regions. SPACE MRA disclosed 7 significant stenoses in 3 PAD patients. Conclusion: ECG-gated SPACE MRA is a promising imaging technique for non-enhanced assessment of the arteries of the lower extremity. (orig.)

  14. Cation Movements during Dehydration and NO2 Desorption in a Ba-Y,FAU zeolite: an in situ Time-resolved X-ray Diffraction Study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianqin; Hanson, Jonathan C.; Kwak, Ja Hun; Szanyi, Janos; Peden, Charles HF

    2013-02-28

    Synchrotron-based in situ time-resolved X-ray diffraction and Rietveld analysis were used to probe the interactions between BaY, FAU zeolite frameworks and H2O or NO2 molecules. These results provided information about the migration of the Ba2+ cations in the zeolite framework during dehydration and during NO2 adsorption/desorption processes in a water free zeolite. In the hydrated structure water molecules form four double rings of hexagonal ice-like clusters [(H2O)6] in the 12-ring openings of the super-cage. These water rings interacted with the cations and the zeolite framework through four cation/water clusters centered over the four 6-membered rings of the super-cage (site II). Interpenetrating tetrahedral water clusters [(H2O)4] and tetrahedral Ba+2 cation clusters were observed in the sodalite cage. Consistent with the reported FT-IR results, three different ionic NOx species (NO+, NO+-NO2, and NO3-) were observed following NO2 adsorption by the dehydrated Ba-Y,FAU zeolite. The structure of the water and the NOx species were correlated with the interactions between the adsorbates, the cations, and the framework. The population of Ba2+ ions at different cationic positions strongly depended on the amount of bound water or NOx species. Both dehydration and NO2 adsorption/desorption resulted in facile migration of Ba2+ ions among the different cationic positions. Data obtained in this work have provided direct evidence for the Ba2+ cation migration to accommodate the binding of gas molecules. This important feature may play a pivotal role in the strong binding of NO2 to Ba-Y,FAU zeolite, a prerequisite for high catalytic activity in lean NOx reduction catalysis.

  15. Wavelength-selective fluorescence in ion channels formed by ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Gramicidins are linear peptides that form ion channels that are specific for monovalent cations in membranes. The tryptophan residues in the gramicidin channel play a crucial role in the orga- nization and function of the channel. The natural mixture of gramicidins, denoted as gramicidin A′, con- sists of mostly ...

  16. Wavelength-selective fluorescence in ion channels formed by ...

    Indian Academy of Sciences (India)

    Gramicidins are linear peptides that form ion channels that are specific for monovalent cations in membranes. The tryptophan residues in the gramicidin channel play a crucial role in the organization and function of the channel. The natural mixture of gramicidins, denoted as gramicidin A', consists of mostly gramicidin A, but ...

  17. Comparison contemporary methods of regeneration sodium-cationic filters

    Science.gov (United States)

    Burakov, I. A.; Burakov, A. Y.; Nikitina, I. S.; Verkhovsky, A. E.; Ilyushin, A. S.; Aladushkin, S. V.

    2017-11-01

    Regeneration plays a crucial role in the field of efficient application sodium-cationic filters for softening the water. Traditionally used as regenerant saline NaCl. However, due to the modern development of the energy industry and its close relationship with other industrial and academic sectors the opportunity to use in the regeneration of other solutions. The report estimated data and application possibilities as regenerant solution sodium-cationic filters brine wells a high mineral content, as both primary application and after balneotherapeutic use reverse osmosis and concentrates especially recycled regenerant water repeated. Comparison of the effectiveness of these solutions with the traditional use of NaCl. Developed and tested system for the processing of highly mineralized brines wells after balneological use. Recommendations for use as regeneration solutions for the sodium-cationic unit considered solutions and defined rules of brine for regeneration costs.

  18. Cationization of Alpha-Cellulose to Develop New Sustainable Products

    Directory of Open Access Journals (Sweden)

    Ana Moral

    2015-01-01

    Full Text Available Papermaking has been using high quantities of retention agents, mainly cationic substances and organic compounds such as polyamines. The addition of these agents is related to economic and environmental issues, increasing contamination of the effluents. The aim of this work is to develop a cationic polymer for papermaking purposes based on the utilization of alpha-cellulose. The cationization of mercerized alpha-cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC is governed by a pseudo-second-order reaction. The initial amorphous fraction of cellulose is reacted with CHPTAC until the equilibrium value of nitrogen substitution is reached. Nitrogen is incorporated as a quaternary ammonium group in the polymer. Also, the kinetic constant increased with decreasing crystallinity index, showing the importance of the previous alkalization stage. The use of modified natural polysaccharides is a sustainable alternative to synthetic, nonbiodegradable polyelectrolytes and thus is desirable with a view to developing new products and new processes.

  19. Structure and Intramolecular Proton Transfer of Alanine Radical Cations

    International Nuclear Information System (INIS)

    Lee, Gab Yong

    2012-01-01

    The structures of the four lowest alanine conformers, along with their radical cations and the effect of ionization on the intramolecular proton transfer process, are studied using the density functional theory and MP2 method. The energy order of the radical cations of alanine differs from that of the corresponding neutral conformers due to changes in the basicity of the NH 2 group upon ionization. Ionization favors the intramolecular proton transfer process, leading to a proton-transferred radical-cation structure, [NH 3 + -CHCH 3 -COO·], which contrasts with the fact that a proton-transferred zwitterionic conformer is not stable for a neutral alanine in the gas phase. The energy barrier during the proton transfer process is calculated to be about 6 kcal/mol

  20. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    International Nuclear Information System (INIS)

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang.

    1996-01-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer

  1. Vibronic and cation spectroscopy of 2,4-difluoroaniline

    Science.gov (United States)

    Huang, Wei Chih; Huang, Po Sheng; Hu, Ching Han; Tzeng, Wen Bih

    We applied the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 2,4-difluoroaniline. The cation spectra were recorded by ionizing via the 00, X1, 6b1, and 11 levels of the electronically excited S1 state. Most of the observed active modes of this molecule in the S1 and cationic ground D0 states are related to the in-plane ring deformation vibrations. The band origin of the S1 ← S0 electronic excitation was found to appear at 33 294 ± 2 cm-1, whereas the adiabatic ionization energy was determined to be 63 935 ± 5 cm-1. Comparing the data of 2,4-difluoroaniline with those of aniline, 2-fluoroaniline, and 4-fluoroaniline, one can learn the effects of fluorine substitution on the electronic transition and molecular vibration.

  2. Changing of Cations Concentrations in Waters of Polluted Urban River

    Directory of Open Access Journals (Sweden)

    Andrianova Maria

    2016-01-01

    Full Text Available Water from urban river Okhta polluted with domestic and industrial wastewaters was investigated. Specific electric conductivity (k, molar concentrations of ions Na+, K+, Mg++ and Ca++, concentration of total nitrogen (TN were measured in water samples. Increasing of k happened together with increasing of molar fraction of sodium-ion (RNa among all studied cations (and correspondingly decreasing of molar fractions of other cations. Good correlations were found between RNa and TN (r = 0.67, k and TN (r = 0.84. The results support the idea of the leading role of wastewaters in changing of k and cations concentrations. Electric conductivity and RNa could be used to distinguish between polluted and not polluted waters in the Okhta.

  3. The Zintl-Klemm concept applied to cations in oxides. I. The structures of ternary aluminates.

    Science.gov (United States)

    Santamaría-Pérez, David; Vegas, Angel

    2003-06-01

    The structures of 94 ternary aluminates are reinterpreted on the basis of the Zintl-Klemm concept and Pearson's generalized octet rule. In aluminates of highly electropositive metals such as alkali, alkaline-earth and rare-earth metals, the Al atoms form three-dimensional skeleta which can be interpreted as if the Al atoms were behaving as Zintl polyanions, adopting the structure of either main-group elements or Zintl polyanions showing the same connectivity. The O atoms are then located close to both the hypothetical two-electron bonds and the lone pairs, giving rise to a tetrahedral coordination. When more electronegative elements, such as W or Si, are present in the compound, the electron transfer towards the Al atoms does not take place. In this case, aluminium behaves as a base, transferring its electrons to the more electronegative atoms and the coordination sphere of aluminium becomes octahedral. In some compounds the Al atoms clearly show amphoteric character so that some Al atoms act as donors (bases) and hence are octahedrally coordinated, whereas others behave as acceptors (acids), adopting a tetrahedral coordination. From this it is concluded that the coordination sphere of aluminium is not a function of the ionic radius of the Al(3+) cations, but it depends on the nature of the other cations accompanying them in the structure. The networks formed by these aluminates are, in many instances, similar to those of the binary oxides of the main-group elements. For this reason, a systematic survey of these oxides is also reported. Compounds such as stuffed cristobalites and trydimites and also perovskites are examples of this new interpretation. Perovskites are then reinterpreted as a stuffed pseudo-TeO(3) structure. Other families of compounds such as silicates and phosphates are susceptible to a similar interpretation. This study provides additional examples of how cations recognize themselves in spite of being embedded in an oxygen matrix.

  4. Cationic mobility in polystyrene sulfone exchangers - Application to the elution of a cation on an exchange column

    International Nuclear Information System (INIS)

    Menin, Jean-Pierre

    1969-01-01

    The aim of this work is to improve elutions and separations carried out on inorganic exchangers by selective electromigration of the ionic species to be displaced. To do this, it has been found indispensable to make a fundamental study of the mobility of cations in exchangers. As the field for this research we have chosen those organic exchangers whose structure and behaviour with respect to ion-exchange are much better known that in the case of their inorganic equivalents. We have related the idea of the equivalent conductivity to that of the cation mobility in the exchanger, and this has entailed determining the specific conductivity of the exchanger and the cation concentration in the resin. The results obtained have allowed us to draw up a hypothesis concerning the cation migration mechanism in the exchanger. The third part of our work has been the application of the preceding results to an operation on an ion-exchange column, viz. the elution by an acid solution of a single fixed ion, magnesium or strontium. This work has enabled us to show that the electromigration of a cation during its elution can markedly accelerate or retard this elution. (author) [fr

  5. Effect of cation exchange of major cation chemistry in the large scale redox experiment at Aespoe. Revision 1

    International Nuclear Information System (INIS)

    Viani, B.E.; Bruton, C.J.

    1996-06-01

    Geochemical modeling was used to test the hypothesis that cation exchange with fracture-lining clays during fluid mixing in the Aespoe Hard Rock Laboratory can significantly affect major element chemistry. Conservative mixing models do not adequately account for changes in Na, Ca and Mg concentrations during mixing. Mixing between relatively dilute shallow waters and more concentrated waters at depth along fracture zones was modeled using the EQ3/6 geochemical modeling package. A cation exchange model was added to the code to describe simultaneously aqueous speciation, mineral precipitation/dissolution, and equilibration between a fluid and a cation exchanger. Fluid chemistries predicted to result from mixing were compared with those monitored from boreholes intersecting the fracture zone. Modeling results suggest that less than 0.1 equivalent of a smectite exchanger per liter of groundwater is necessary to account for discrepancies between predictions from a conservative mixing model and measured Na and Ca concentrations. This quantity of exchanger equates to an effective fracture coating thickness of 20 microm or less given a fracture aperture width of 1,000 microm or less. Trends in cation ratios in the fluid cannot be used to predict trends in cation ratios on the exchanger because of the influence of ionic strength on heterovalent exchange equilibrium. It is expected that Na for Ca exchange will dominate when shallow waters such as HBHO2 are mixed with deeper waters. In contrast, Na for Mg exchange will dominate mixing between deeper waters

  6. Impact of spreading olive mill waste water on agricultural soils for leaching of metal micronutrients and cations.

    Science.gov (United States)

    Aharonov-Nadborny, R; Tsechansky, L; Raviv, M; Graber, E R

    2017-07-01

    Olive mill waste water (OMWW) is an acidic (pH 4-5), saline (EC ∼ 5-10 mS cm -1 ), blackish-red aqueous byproduct of the three phase olive oil production process, with a high chemical oxygen demand (COD) of up to 220,000 mg L -1 . OMWW is conventionally disposed of by uncontrolled dumping into the environment or by semi-controlled spreading on agricultural soils. It was hypothesized that spreading such liquids on agricultural soils could result in the release and mobilization of indigenous soil metals. The effect of OMWW spreading on leaching of metal cations (Na, K, Mg, Mn, Fe, Cu, Zn) was tested in four non-contaminated agricultural soils having different textures (sand, clay loam, clay, and loam) and chemical properties. While the OMWW contributed metals to the soil solution, it also mobilized indigenous soil metals as a function of soil clay content, cation exchange capacity (CEC), and soil pH-buffer capacity. Leaching of soil-originated metals from the sandy soil was substantially greater than from the loam and clay soils, while the clay loam was enriched with metals derived from the OMWW. These trends were attributed to cation exchange and organic-metal complex formation. The organic matter fraction of OMWW forms complexes with metal cations; these complexes may be mobile or precipitate, depending on the soil chemical and physical environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Clinical value of indicators of cationic proteins, leukocytes myeloperoxidase and fibronectin blood plasma in viral meningitis in children

    Directory of Open Access Journals (Sweden)

    O. G. Kimirilova

    2017-01-01

    Full Text Available Objective: was to establish clinical and diagnostic value of cytochemical indices of peripheral blood leukocytes (cationic protein and myeloperoxidase, fibronectin blood plasma to assess the severity, predict the course and outcome of viral meningitis in children.Subjects and methods. In 450 patients with viral meningitis (enterovirus, arbovirus, parotitic, herpesviral, adenovirus etiology at the age of 14 years, the parameters of the microbicidal system of leukocytes (cation proteins, myeloperoxidase and fibronectin blood plasma were determined. Etiological diagnosis of meningitis was confirmed by release of viral RNA from blood and cerebrospinal fluid by the polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA.The results and conclusion. Found that severe, prolonged duration, lethal outcome of viral meningitis in children are accompanied by sugnificant suppression of cationic proteins, myeloperoxidase, fibronectin blood plasma, maximally expressed in lethal outcomes, compared with the severe form, but with a favorable outcome and control. Settings imbalance cationic proteins, myeloperoxidase, fibronectin blood plasma are objective criteria of the adaptation syndrome that reflects the state of the phagocytosis system in viral meningitis in children and can be considered as additional criteria for predicting the course and outcome of disease.

  8. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Mnasra (MN) : situé au niveau du Gharb sous forme d'une bande longeant la méditerranée vers l'embouchure du Sebou au niveau de l'océan Atlantique. 2-2. Prélèvement des échantillons (eaux d'irrigation, sols agricoles et cultures). Cinq campagnes de prélèvement ont été effectuées entre juillet 2006 et juillet 2010 et ont ...

  9. Network diversity through decoration of trigonal-prismatic nodes: Two-step crystal engineering of cationic metal-organic materials

    KAUST Repository

    Schoedel, Alexander

    2011-10-05

    MOMs the word! In a two-step process, first a trigonal-prismatic Primary Molecular Building Block ([Cr3O(isonic)6]+, tp-PMBB-1) was formed and then it was connected to linear linkers or square-planar nodes to afford three novel highly charged cationic metal-organic materials (MOMs) with snx, snw, and stp topologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Two Organic Cation Salts Containing Tetra(isothiocyanatecobaltate(II: Synthesis, Crystal Structures, Spectroscopic, Optical and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Zheng Zhang

    2017-03-01

    Full Text Available Single crystals of two hybrid organic-inorganic molecular solids, benzyl pyridinium tetra(isothiocyanatecobalt ([BzPy]2[Co(NCS4] (1 and benzyl quinolinium tetra(isothiocyanatecobalt ([BzQl]2[Co(NCS4] (2, were grown using a slow evaporation growth technique at room temperature and their IR, UV-Vis, X-ray crystal structures, luminescence, and magnetism were reported. The crystal structural analysis revealed that two molecular solids crystallize in the monoclinic space group P21/c of 1 and P21/n of 2. The cations form a dimer through weak C–H···π/π···π interactions in 1 and 2, and the adjacent cation (containing N(6 atom in 2 forms a columnar structure through π···π weak interactions between the quinoline and benzene rings, while the anions in 1 form a layer structure via short S···Co interactions. The anions (A and cations (C are arranged alternatively into a column in the sequence of ···A–CC–A–CC–A··· for 1, while the two anions and cationic dimer in 2 form an alliance by the C–H···π, C–H···S and C–H···N hydrogen bonds. A weak S···π interaction was found in 1 and 2. The two molecular solids show a broad fluorescence emission around 400 nm in the solid state at room temperature, and weak antiferromagnetic coupling behavior when the temperature is lowered.

  11. Renaissance of cation-radicals in mass spectrometry.

    Science.gov (United States)

    Tureček, František

    2013-01-01

    This brief overview addresses the topic that was presented in the Thomson Medal Award session at the 19th International Mass Spectrometry Conference in Kyoto, Japan. Mass spectrometry of cation-radicals has enjoyed a remarkable renaissance thanks to the development of new methods for electron attachment to multiply charged peptide ions. The charge-reduced ions that are odd-electron species exhibit interesting reactivity that is useful for peptide and protein sequencing. The paper briefly reviews the fundamental aspects of the formation, energetics, and backbone dissociations of peptide cation-radicals.

  12. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    DEFF Research Database (Denmark)

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

    2010-01-01

    We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

  13. Use of the Rietveld technique for estimating cation distributions

    International Nuclear Information System (INIS)

    Nord, A.G.

    1984-01-01

    The use of the Rietveld full-profile refinement technique to estimate cation distributions is exemplifed by a neutron powder diffraction study of the farringtonite-type solid solution γ-(Znsub(0.70)Fesub(0.30)) 3 (PO 4 ) 2 , with five- and six-coordinated cation sites. A review of similar studies of phases with the farringtonite, sarcopside, Ni 2 P 4 O 12 or olivine structure is given. The accuracy is discussed in terms of Ksub(D) distribution coefficients and metal-oxygen distances. Some investigations of olivines based on X-ray single-crystal data are reviewed for comparison. (Auth.)

  14. Formation of the N-Iodopyridinium Cation in an Alkane Environment

    DEFF Research Database (Denmark)

    Spanget-Larsen, Jens

    2006-01-01

    It is well known that pyridine (py) and iodine (I2) form a 1:1 molecular complex, py-I2. Within the framework of a student project at Roskilde University [1], we have recently investigated the formation and mid-infrared linear dichroism of the complex in a stretched polyethylene (PE) matrix......-iodopyridinium cation (pyI+). This assignment is consistent with the observed polarization data. Ionic side reactions (py-I2 = pyI+ + I–, py-I2 + I2 = pyI+ + I3–, etc.) are easily observed in binary pyridine-iodine mictures and in polar solvents, but not so easily in non-polar media. We are thus surprised to see...... the apparent efficiency with which the pyI+ cation is formed in an apolar and aprotic medium like PE. With excess iodine, the peaks assigned to pyI+ dominate the observed mid-infrared spectrum. We suspect that a driving force for the ionic reaction is the formation of polyiodide anions in the channels...

  15. Asymmetric partitioning of metals among cluster anions and cations generated via laser ablation of mixed aluminum/Group 6 transition metal targets.

    Science.gov (United States)

    Waller, Sarah E; Mann, Jennifer E; Jarrold, Caroline Chick

    2013-02-28

    While high-power laser ablation of metal alloys indiscriminately produces gas-phase atomic ions in proportion to the abundance of the various metals in the alloy, gas-phase ions produced by moderate-power laser ablation sources coupled with molecular beams are formed by more complicated mechanisms. A mass spectrometric study that directly compares the mass distributions of cluster anions and cations generated from laser ablation of pure aluminum, an aluminum/molybdenum mixed target, and an aluminum/tungsten mixed target is detailed. Mass spectra of anionic species generated from the mixed targets showed that both tungsten and molybdenum were in higher abundance in the negatively charged species than in the target material. Mass spectra of the cationic species showed primarily Al(+) and aluminum oxide and hydroxide cluster cations. No molybdenum- or tungsten-containing cluster cations were definitively assigned. The asymmetric distribution of aluminum and Group 6 transition metals in cation and anion cluster composition is attributed to the low ionization energy of atomic aluminum and aluminum suboxide clusters. In addition, the propensity of both molybdenum and tungsten to form metal oxide cluster anions under the same conditions that favor metallic aluminum cluster anions is attributed to differences in the optical properties of the surface oxide that is present in the metal powders used to prepare the ablation targets. Mechanisms of mixed metal oxide clusters are considered.

  16. Differential effects of selective frankincense (Ru Xiang) essential oil versus non-selective sandalwood (Tan Xiang) essential oil on cultured bladder cancer cells: a microarray and bioinformatics study

    Science.gov (United States)

    2014-01-01

    cancer cell death. While frankincense essential oil elicited selective cancer cell death via NRF-2-mediated oxidative stress, sandalwood essential oil induced non-selective cell death via DNA damage and cell cycle arrest. PMID:25006348

  17. The influence of temperature and P/P0 upon cationic exchange constants

    International Nuclear Information System (INIS)

    Blanc, P.; Vieillard, P.; Gailhanou, H.; Gaboreau, S.; Gaucher, E.C.; Giffaut, E.

    2010-01-01

    Document available in extended abstract form only. The knowledge of thermodynamic properties of clay minerals forming clay materials is important in the context of a disposal within clayey formations (Callovo-Oxfordian argillite) or for clayey barriers. Different experiments have been previously performed concerning the long term behavior of clay materials, indicating that strong transformations are influenced by the alkaline solutions issued from the cementitious materials. But the first stages of the transformations affect the hydration and exchange capacity of the mineral, which are closely related to their retention properties. This work aims at assessing the influence of temperature and relative humidity upon the thermodynamic functions related to cationic exchange and hydration reactions. It is carried out within the framework of the Thermochimie project, aiming at defining a consistent thermodynamic database for modeling purposes. This work is an extension of the thermodynamic of hydration study carried out by Vieillard et al. (2010). Using the same, regular, solid solution model developed by the authors, we first consider the influence of temperature on the hydration reaction by expressing the hydration constant LogK hyd (T) according to the enthalpy and entropy of hydration and to the gas constant. Predicted isotherms are then compared with experimental data acquired on the MX80 smectite at 40, 60, 75, 90 and 100 deg. C. We now consider a cationic exchange reaction between cations A+ and B+, with z cations per mole of smectite and y2 and y1 mole of water per mole of smectite for A and B end members, respectively. The exchange constant LogK A/B , for a given temperature and relative humidity, is expressed as a function of the difference between anhydrous end members, and of the difference between anhydrous end-members activities. A comparison with room temperature exchange constants derived from experiments suggests that discrepancies are related to

  18. Cationic starches on cellulose surfaces : a study of polyelectrolyte adsorption

    NARCIS (Netherlands)

    Steeg, van de H.G.M.

    1992-01-01

    Cationic starches are used on a large scale in paper industry as wet-end additives. They improve dry strength. retention of fines and fillers, and drainage. Closure of the white water systems in the paper mills hase increased the concentration of detrimental substances. This might be the

  19. Solidification cracking in austenitic stainless steel welds

    Indian Academy of Sciences (India)

    Solidification cracking is a significant problem during the welding of austenitic stainless steels, particularly in fully austenitic and stabilized compositions. Hot cracking in stainless steel welds is caused by low-melting eutectics containing impurities such as S, P and alloy elements such as Ti, Nb. The WRC-92 diagram can be ...

  20. Cationic polymers for nuclaic acid delivery to tumors

    NARCIS (Netherlands)

    Wolf, H.K. de

    2007-01-01

    In the field of cancer gene therapy, the use of gene carrier systems is considered indispensable. Cationic polymers are able to effectively condense plasmid DNA to nano-sized particles, further referred to as polyplexes. Compared to free DNA, polyplexes have shown improved nuclease-resistance, a

  1. Dietary cation anion difference: Impact on productive and ...

    African Journals Online (AJOL)

    Various nutritional tools have been used to improve the productive and reproductive performance of animals, among which difference between certain minerals, called dietary cation anion difference (DCAD) plays a pivotal role. Low or negative DCAD diets reduce blood pH and HCO3- and animal becomes acidotic.

  2. Fabrication of Cationic Exchange Polystyrene Nanofibers for Drug ...

    African Journals Online (AJOL)

    Trop J Pharm Res, February 2014; 13(2): 192. Many polymers are used to produce nanofibers by electrospinning. Polystyrene (PS) is one of polymers used to produce cation exchange fibers. [9]. PS nanofibers were successfully produced using the electrospinning method and it has been demonstrated that electrospun PS.

  3. Tuning underwater adhesion with cation-π interactions

    Science.gov (United States)

    Gebbie, Matthew A.; Wei, Wei; Schrader, Alex M.; Cristiani, Thomas R.; Dobbs, Howard A.; Idso, Matthew; Chmelka, Bradley F.; Waite, J. Herbert; Israelachvili, Jacob N.

    2017-05-01

    Cation-π interactions drive the self-assembly and cohesion of many biological molecules, including the adhesion proteins of several marine organisms. Although the origin of cation-π bonds in isolated pairs has been extensively studied, the energetics of cation-π-driven self-assembly in molecular films remains uncharted. Here we use nanoscale force measurements in combination with solid-state NMR spectroscopy to show that the cohesive properties of simple aromatic- and lysine-rich peptides rival those of the strong reversible intermolecular cohesion exhibited by adhesion proteins of marine mussel. In particular, we show that peptides incorporating the amino acid phenylalanine, a functional group that is conspicuously sparing in the sequences of mussel proteins, exhibit reversible adhesion interactions significantly exceeding that of analogous mussel-mimetic peptides. More broadly, we demonstrate that interfacial confinement fundamentally alters the energetics of cation-π-mediated assembly: an insight that should prove relevant for diverse areas, which range from rationalizing biological assembly to engineering peptide-based biomaterials.

  4. Changes in Cations Distribution on Degraded Soils of Otamiri ...

    African Journals Online (AJOL)

    This study evaluated changes cations distribution in degraded soils Otamiri floodplain, having 4 easily idenfiable physiographic land units, namely Upland, Terrace, Levee and Backswamp. Results showed high degradation in Upland and Terrace soils. (Ca/Mg ≤ 3.0) when compared with Levee and Backswamp soils ...

  5. Relative solubility of cations in Class F fly ash.

    Science.gov (United States)

    Kim, Ann G; Kazonich, George; Dahlberg, Michael

    2003-10-01

    Coal utilization byproducts (CUB), such as fly ash, contain cations that may be released during exposure to fluids such as acid rain or acid mine drainage. Researchers at the Department of Energy's National Energy Technology Laboratory (DOE/NETL) have conducted a long-term column leaching study of 32 Class F fly ash samples from pulverized coal (PC) combustion, and quantified the release of 19 cations in four leachants with a pH between 1.2 and 12. The relative solubility (M(L/T)) of each cation was defined as the total mass leached (M(L)) relative to the concentration (M(T)) of that element in the fly ash sample. A frequency distribution of relative solubility values was computed with ranges defined as insoluble, slightly soluble, moderately soluble, and very soluble. On the basis of this sample set, Ba, Cd, Fe, Pb, Sb, and Se in PC fly ash are insoluble. The elements Al, Be, Ca, Co, Cr, Cu, K, Mg, Mn, Na, Ni, and Zn are slightly to moderately acid soluble. Only Ca and Na are water soluble; As and Ca are soluble in the basic solution, The results of this study indicate that the extent to which cations in Class F PC fly ash can be leached by naturally occurring fluids is very limited.

  6. Cations Content And Membrane Properties Of Human Sickle Blood ...

    African Journals Online (AJOL)

    Human sickle blood was incubated with the drugs in vitro at their optimum sickling inhibitory concentration. Mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), cations (Na+, K+ and Ca2+) contents and viscosity were measured. Tellurite and thiocyanate significantly increased (P 0.05) ...

  7. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.

    2005-01-01

    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  8. Fly ash adsorbents for multi-cation wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Visa, Maria, E-mail: maria.visa@unitbv.ro [Transilvania University of Brasov, Dept. Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania); Isac, Luminita; Duta, Anca [Transilvania University of Brasov, Dept. Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania)

    2012-06-15

    Class 'F' fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO{sub 2}/Al{sub 2}O{sub 3} over 2.4 proved good adsorbent properties, and was further used for obtaining a new substrate with good adsorption capacity for heavy metals from multi-cation wastewater treatment. Firstly, the new adsorbent was characterized by AFM, XRD, DSC, FTIR and the surface energy was evaluated by contact angle measurements. The experimental data suggested that the new type of substrate is predominant crystalline with highly polar surface. The substrate was used for removing the Pb{sup 2+}, Cd{sup 2+} and Zn{sup 2+} cations from mixed solutions. The results show high efficiency and selective adsorption the Pb{sup 2+} and Zn{sup 2+} cations. The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes. The Langmuir and Freundlich models were used to describe the processes. The pseudo-second order kinetics could well model all the processes, indicating a surface concentration of the adsorption sites with the same order of magnitude as the cation concentrations.

  9. Esterification of maleic acid and butanol using cationic exchange ...

    Indian Academy of Sciences (India)

    AARTI MULAY

    2017-11-15

    Nov 15, 2017 ... Abstract. Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives, and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange resin as a catalyst. The objective of this work was to test the suitability and efficacy of ...

  10. Coordination of lanthanide cation to an Anderson type ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 5. Coordination of lanthanide cation to an Anderson type polyoxometalate anion ... and spectroscopy. Vaddypally Shivaiah Tanmay Chatterjee Samar K Das. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1525-1533 ...

  11. Stabilizing cations in the backbones of conjugated polymers

    NARCIS (Netherlands)

    Voortman, Thomas P.; de Gier, Hilde D.; Havenith, Remco W. A.; Chiechi, Ryan C.

    2014-01-01

    We synthesized a cross-conjugated polymer containing ketones in the backbone and converted it to a linearly conjugated, cationic polyarylmethine via a process we call "spinless doping" to create a new class of materials, conjugated polyions. This process involves activating the ketones with a Lewis

  12. Computer simulation of superionic conductors: II. Cationic conductors. Review

    International Nuclear Information System (INIS)

    Ivanov-Shitz, A. K.

    2007-01-01

    The state of the art of the molecular-dynamics simulation of superionic conductors is reviewed. The main studies devoted to the structural, dynamic, and transport properties of the basic classes of solid electrolytes with conductivity via silver, copper, lithium, sodium, and hydrogen cations are considered. The premelting effect in ionic crystals is discussed

  13. Two different cationic positions in Cu-SSZ-13?

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Zhu, Haiyang; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-04-18

    H2-TPR and FTIR were used to characterize the Cu ions present in Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions in two distinct cationic positions of the SSZ-13 framework.

  14. Weight gradient and physiological responses to cation-treatment by ...

    African Journals Online (AJOL)

    There was regular taking of body weight of the rabbits using a top- loading weighing balance, while feed consumption, rectal temperature, stool frequency, physical appearance and behavioural changes were noted. Weight gradient studies show gradual increase in body weight following cation treatment of rabbits, but after ...

  15. Aqueous solubility of ciprofloxacin in the presence of metal cations ...

    African Journals Online (AJOL)

    Purpose: Though the complexation of ciprofloxacin with metal cations has been extensively studied, the effect of this complexation on the aqueous solubility of ciprofloxacin which is an important factor affecting drug distribution has not been well documented. We have thus set out in this study to investigate the aqueous ...

  16. Micellization of a Cationic Surfactant in Mixed Aqueous and Non ...

    African Journals Online (AJOL)

    Reception

    surfactant molecules arrange themselves in bulk solutions into aggregates otherwise called micelles when the interface is fully saturated with the surfactant molecules. Micelle formation is driven by hydrophobic effect but opposed by electrostatic repulsion of the ionic head group (Jiang et al., 2009). Cationic surfactants like ...

  17. Small angle neutron scattering studies on the interaction of cationic

    Indian Academy of Sciences (India)

    The structure of the protein–surfactant complex of bovine serum albumin (BSA) and cationic surfactants has been studied by small angle neutron scattering. At low concentrations, the CTAB monomers are observed to bind to the protein leading to an increase in its size. On the other hand at high concentrations, surfactant ...

  18. Structure and Reactivity of the Cysteine Methyl Ester Radical Cation

    NARCIS (Netherlands)

    Osburn, S.; Steill, J. D.; Oomens, J.; O' Hair, R. A. J.; Van Stipdonk, M.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the cysteine methyl ester radical cation, CysOMe(center dot+), have been examined in the gas phase using a combination of experiment and density functional theory (DFT) calculations. CysOMe(center dot+) undergoes rapid ion molecule reactions with dimethyl disulfide,

  19. Dipicolinate complexes of main group metals with hydrazinium cation

    Indian Academy of Sciences (India)

    Unknown

    Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae ... dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements ... group metals, and the ability of dip2– to function as a tridentate ligand, we expect to find anionic complexes of the type ...

  20. A tetrakis (amido) phosphonium cation containing 2-pyridyl (2 Py ...

    Indian Academy of Sciences (India)

    amido)phosphonium cation containing 2-pyridyl (2Py) substituents,[P(NH2Py)4]+ and its reactivity studies with Ag(I) salts ... Abstract. Poly-imido analogues of various phosphorus oxo anions have gained recent attention in inorganic chemistry.

  1. Cation exchange applications of synthetic tobermorite for the ...

    Indian Academy of Sciences (India)

    Immobilization and solidification of hazardous cations like Cs137 and Sr90 are required while handling the radioactive waste of nuclear power plants. Efforts are on to find a fail proof method of safe disposal of nuclear wastes. In this context, various materials like borosilicate glass, zeolites, cements and synthetic rocks have ...

  2. Esterification of maleic acid and butanol using cationic exchange ...

    Indian Academy of Sciences (India)

    AARTI MULAY

    2017-11-15

    Nov 15, 2017 ... Special Issue on Recent Trends in the Design and Development of Catalysts and their Applications. Esterification of maleic acid and butanol using cationic exchange resin as ..... Thus, the mole ratio of maleic acid to n-butanol was also varied as 1:3, 1:4, and 1:5 keeping other parameters at a constant value ...

  3. membrane potential change effects on cationic and neutral drug

    African Journals Online (AJOL)

    USER

    NWAFOR A AND COAKLEY W. T. 1Department of Human Physiology, College of Health Sciences University Of Port Harcourt,. Nigeria. 2School of Pure and Applied Biology University of Wales, College of Cardiff, Cathay's Park,. Cardiff, U.K.. The effect of membrane potential change of the human erythrocytes on cationic ...

  4. The exchangeable cations in soils flooded with sea water

    NARCIS (Netherlands)

    Molen, van der W.H.

    1958-01-01

    The changes in the exchangeable cations of soils flooded with sea-water were extensively studied in the Netherlands after the inundations of 1940, 1945 and 1953. A synopsis of the results was given, both from a theoretical and a practical viewpoint.

    Current formulae for ion-exchange tested in the

  5. Adaptive resistance to cationic compounds in Pseudomonas aeruginosa.

    Science.gov (United States)

    Skiada, Anna; Markogiannakis, Antonis; Plachouras, Diamantis; Daikos, George L

    2011-03-01

    Adaptive resistance is an autoregulated phenomenon characterised by induction of resistance in the presence of drug and reversal to the sensitive phenotype in its absence. This type of resistance is well documented for polycationic antibiotics, including aminoglycosides and polymyxins, in Pseudomonas aeruginosa and other aerobic Gram-negative bacilli. It is not caused by selection of resistant mutants but rather by phenotypic alterations in order to survive the lethal drug effect. Adaptive resistance to aminoglycosides is mainly mediated by the MexXY-OprM efflux pump that is rapidly upregulated in bacteria surviving the first exposure to aminoglycosides and is downregulated when bacteria are no longer in contact with the drug. A two-component regulatory system designated ParR-ParS plays a major role in adaptive resistance induced by cationic peptides. In the presence of cationic peptides, ParR-ParS activates the lipopolysaccharide modification operon (arnBCADTEF) leading to increased resistance in polymyxins and aminoglycosides. The bactericidal kinetics related to adaptive resistance have important clinical implications and provide a rationale for administering cationic antibiotics in larger initial and longer interval bolus dosing. A better understanding of this phenomenon and the molecular mechanisms responsible will be essential not only for optimum use of cationic antibiotics but also for developing new agents with ability to counteract the detrimental effects of adaptive resistance and thus enhance the therapeutic efficacy of polycationic compounds. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  6. Molecular determinants of permeation through the cation channel TRPM6.

    NARCIS (Netherlands)

    Topala, C.N.; Groenestege, W.T.; Thebault, S.C.; Berg, D. Van den; Nilius, B.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2007-01-01

    TRPM6 and its closest relative TRPM7 are members of the Transient Receptor Potential Melastatin (TRPM) subfamily of cation channels and are known to be Mg2+ permeable. By aligning the sequence of the putative TRPM6 pore with the pore sequences of the other subfamily members, we located in the loop

  7. One-step scalable preparation method for non-cationic liposomes with high siRNA content.

    Science.gov (United States)

    Somiya, Masaharu; Yamaguchi, Kotomi; Liu, Qiushi; Niimi, Tomoaki; Maturana, Andrés Daniel; Iijima, Masumi; Yoshimoto, Nobuo; Kuroda, Shun'ichi

    2015-07-25

    Cationic liposomes (LPs) have been utilized for short interfering RNA (siRNA) delivery in vitro and in vivo owing to their high affinity for siRNA via electrostatic binding. However, both cytotoxicity and non-specific adsorption of cationic LPs in the body have prevented clinical siRNA applications. These situations have led to siRNA encapsulation in non-cationic LPs. We found that the instillation of neutral phospholipids dissolved in ethanol into aqueous solutions containing siRNA and CaCl2 resulted in high siRNA encapsulation (siRNA encapsulation efficiency: ∼ 80%; siRNA weight ratio: ∼ 10 wt% of LPs). The products were monodispersed, ∼ 200 nm, and negatively charged. Furthermore, when phospholipids with a high-phase transition temperature or cholesterol were used, the encapsulation efficiency and siRNA content remained high. Although anionic LPs could not encapsulate siRNAs using this method, the use of cholesterol-conjugated siRNA helped achieve substantial siRNA encapsulation in anionic LPs. These non-cationic siRNA-containing LPs did not show cytotoxicity in vitro, and could be formed with polyethylene glycol-conjugated phospholipids. When conjugated with targeting ligand, the non-cationic siRNA-containing LPs could suppress the expression of target gene in vitro. These data demonstrate that our preparation method would be suitable for large-scale LP production for systemic siRNA delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Sorption of chlorophenols on microporous minerals: mechanism and influence of metal cations, solution pH, and humic acid.

    Science.gov (United States)

    Yang, Hui; Hu, Yuanan; Cheng, Hefa

    2016-10-01

    Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm(2)) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the "loosely bound" water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a "coating layer" on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream.

  9. Single-stage separation and esterification of cation salt carboxylates using electrodeionization

    Science.gov (United States)

    Lin, YuPo J.; Henry, Michael; Hestekin, Jamie; Snyder, Seth W.; St. Martin, Edward J.

    2006-11-28

    A method of and apparatus for continuously making an organic ester from a lower alcohol and an organic acid is disclosed. An organic acid or salt is introduced or produced in an electrode ionization (EDI) stack with a plurality of reaction chambers each formed from a porous solid ion exchange resin wafer interleaved between anion exchange membranes or an anion exchange membrane and a cation exchange membrane or an anion exchange membrane and a bipolar exchange membranes. At least some reaction chambers are esterification chambers and/or bioreactor chambers and/or chambers containing an organic acid or salt. A lower alcohol in the esterification chamber reacts with an anion to form an organic ester and water with at least some of the water splitting with the ions leaving the chamber to drive the reaction.

  10. Gene Transfection in High Serum Levels: Case Studies with New Cholesterol Based Cationic Gemini Lipids

    Science.gov (United States)

    Misra, Santosh K.; Biswas, Joydeep; Kondaiah, Paturu; Bhattacharya, Santanu

    2013-01-01

    Background Six new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH2CH2OH) and oligo-oxyethylene -(CH2CH2O)n- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media. Methodology/Principal Findings To understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH2-CH2-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features. Conclusions/Significance -OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies. PMID:23861884

  11. Cation trapping by cellular acidic compartments: Beyond the concept of lysosomotropic drugs

    International Nuclear Information System (INIS)

    Marceau, François; Bawolak, Marie-Thérèse; Lodge, Robert; Bouthillier, Johanne; Gagné-Henley, Angélique; Gaudreault, René C.; Morissette, Guillaume

    2012-01-01

    “Lysosomotropic” cationic drugs are known to concentrate in acidic cell compartments due to low retro-diffusion of the protonated molecule (ion trapping); they draw water by an osmotic mechanism, leading to a vacuolar response. Several aspects of this phenomenon were recently reexamined. (1) The proton pump vacuolar (V)-ATPase is the driving force of cationic drug uptake and ensuing vacuolization. In quantitative transport experiments, V-ATPase inhibitors, such as bafilomycin A1, greatly reduced the uptake of cationic drugs and released them in preloaded cells. (2) Pigmented or fluorescent amines are effectively present in a concentrated form in the large vacuoles. (3) Consistent with V-ATPase expression in trans-Golgi, lysosomes and endosomes, a fraction of the vacuoles is consistently labeled with trans-Golgi markers and protein secretion and endocytosis are often inhibited in vacuolar cells. (4) Macroautophagic signaling (accumulation of lipidated and membrane-bound LC3 II) and labeling of the large vacuoles by the autophagy effector LC3 were consistently observed in cells, precisely at incubation periods and amine concentrations that cause vacuolization. Vacuoles also exhibit late endosome/lysosome markers, because they may originate from such organelles or because macroautophagosomes fuse with lysosomes. Autophagosome persistence is likely due to the lack of resolution of autophagy, rather than to nutritional deprivation. (5) Increased lipophilicity decreases the threshold concentration for the vacuolar and autophagic cytopathology, because simple diffusion into cells is limiting. (6) A still unexplained mitotic arrest is consistently observed in cells loaded with amines. An extended recognition of relevant clinical situations is proposed for local or systemic drug administration.

  12. Automated dual capillary electrophoresis system with hydrodynamic injection for the concurrent determination of cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thi Thanh Thuy; Mai, Thanh Duc [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland); Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Nguyen, Thanh Dam [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Sáiz, Jorge [Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering – University of Alcalá, Ctra. Madrid-Barcelona km 33.6, Alcalá de Henares, Madrid 28871 (Spain); Pham, Hung Viet, E-mail: phamhungviet@hus.edu.vn [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Hauser, Peter C., E-mail: Peter.Hauser@unibas.ch [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland)

    2014-09-02

    Highlights: • Concurrent determination of cations and anions was carried out by electrophoretic separation. • Optimized conditions for each class of analystes was possible by using separate capillaries. • Simultaneous hydrodynamic injection was carried out. • Pneumatic actuation was used for flushing and sample handling. • The denitrification of drinking water was successfully demonstrated. - Abstract: The capillary electrophoresis instrument developed for the concurrent determination of cations and anions features two separate capillaries and individual detectors to allow independent optimization for each group of ions. The capillaries are joined in a common injector block. The sample is drawn into the injector with a small membrane pump and automated simultaneous injection into both capillaries is achieved by pressurization of the fluid with compressed air. Flushing of the injector and of the capillaries with the background electrolyte is also carried out automatically by the same means. The buffer consisted of 12 mM histidine and 2 mM 18-crown-6 adjusted to pH 4 with acetic acid and was suitable for the contactless conductivity detection employed. The system was optimized for the determination of cationic NH{sub 4}{sup +} and anionic NO{sub 3}{sup −} and NO{sub 2}{sup −}, and linear calibration curves from about 20 μM up to about 1.5 mM were obtained for these ions. In a test run over 8 h, the reproducibility for the peak areas was within ±7%. For demonstration, the instrument was successfully applied to the concurrent monitoring of the concentrations of the three ions during the biological removal of ammonium from contaminated groundwater in a sequencing batch reactor, where NO{sub 3}{sup −} and NO{sub 2}{sup −} are formed as intermediate products.

  13. Cation trapping by cellular acidic compartments: Beyond the concept of lysosomotropic drugs

    Energy Technology Data Exchange (ETDEWEB)

    Marceau, François, E-mail: francois.marceau@crchul.ulaval.ca [Centre de recherche en rhumatologie et immunologie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1V 4G2 (Canada); Bawolak, Marie-Thérèse [Centre de recherche en rhumatologie et immunologie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1V 4G2 (Canada); Lodge, Robert [Centre de recherche en infectiologie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1V 4G2 (Canada); Bouthillier, Johanne; Gagné-Henley, Angélique [Centre de recherche en rhumatologie et immunologie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1V 4G2 (Canada); Gaudreault, René C. [Unité des Biotechnologies et de Bioingénierie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1L 3L5 (Canada); Morissette, Guillaume [Centre de recherche en rhumatologie et immunologie, Centre Hospitalier Universitaire de Québec, Québec QC, Canada G1V 4G2 (Canada)

    2012-02-15

    “Lysosomotropic” cationic drugs are known to concentrate in acidic cell compartments due to low retro-diffusion of the protonated molecule (ion trapping); they draw water by an osmotic mechanism, leading to a vacuolar response. Several aspects of this phenomenon were recently reexamined. (1) The proton pump vacuolar (V)-ATPase is the driving force of cationic drug uptake and ensuing vacuolization. In quantitative transport experiments, V-ATPase inhibitors, such as bafilomycin A1, greatly reduced the uptake of cationic drugs and released them in preloaded cells. (2) Pigmented or fluorescent amines are effectively present in a concentrated form in the large vacuoles. (3) Consistent with V-ATPase expression in trans-Golgi, lysosomes and endosomes, a fraction of the vacuoles is consistently labeled with trans-Golgi markers and protein secretion and endocytosis are often inhibited in vacuolar cells. (4) Macroautophagic signaling (accumulation of lipidated and membrane-bound LC3 II) and labeling of the large vacuoles by the autophagy effector LC3 were consistently observed in cells, precisely at incubation periods and amine concentrations that cause vacuolization. Vacuoles also exhibit late endosome/lysosome markers, because they may originate from such organelles or because macroautophagosomes fuse with lysosomes. Autophagosome persistence is likely due to the lack of resolution of autophagy, rather than to nutritional deprivation. (5) Increased lipophilicity decreases the threshold concentration for the vacuolar and autophagic cytopathology, because simple diffusion into cells is limiting. (6) A still unexplained mitotic arrest is consistently observed in cells loaded with amines. An extended recognition of relevant clinical situations is proposed for local or systemic drug administration.

  14. Silver Cation Coordination Study to AsW9 Ligand – A Trilacunar Arsenotungstate Compound

    Directory of Open Access Journals (Sweden)

    Berta Lavinia

    2017-06-01

    Full Text Available Objective: The main objective of this research is to find the coordination ratio between AsW9 and Ag+, as a preliminary study for synthesizing a new silver-arsenotungstate complex. Material and method: The ligand:cation molar ratio in complexes was determined by conductometric and potentiometric titrations of AsW9 with silver salts: CH3COOAg, AgNO3. Results: The ratio was obtained from the inflexion points of the curves when molar ratio was plotted versus conductivity, or from the equivalence point when silver added volume was plotted versus pH value. Each graphic shows one point of inflexion corresponding to 1:1.54 ratio of AsW9:Ag+. In the same manner, the equivalent volumes determined by graphical method gave the ratio 1:1.53. The spectral results confirmed that a AsW9:Ag+ complex was formed since the ligand absorption maxima values have been changed from 190 nm to 197 nm in the case of using AgNO3 and 196 nm for CH3COOAg corresponding to the W=Od bond, and from 246.5 nm to 274 nm (AgNO3 and 270 nm (CH3COO-Ag+ for the W-Ob,c-W bond. Conclusions: Silver cation exhibit a preference for AsW9 in a ratio of 3 to 2. This ratio can be associated to a sandwich type arrangement, with two trilacunary Keggin building blocks incorporating 3 metal cations in a tetrahedral geometry.

  15. Total Syntheses of Polycyclic Polyprenylated Acylphloroglucinol Natural Products and Analogs Utilizing Alkylative Dearomatizations and Cationic Cyclizations

    Science.gov (United States)

    Boyce, Jonathan H.

    Polycyclic polyprenylated acylphloroglucinols (PPAPs) are structurally complex natural products with promising biological activities. These compounds have interesting anticancer and anti-HIV properties as well as other biological activities making them highly attractive synthetic targets. We report a stereodivergent, asymmetric total synthesis of (-)-clusianone in six steps from commercial materials. We have implemented a challenging cationic cyclization forging a bond between two sterically encumbered quaternary carbon atoms. Mechanistic studies point to the unique ability of formic acid to mediate the cyclization forming the clusianone framework. We also present a biosynthesis-inspired, diversity-oriented synthesis approach for rapid construction of PPAP analogs via palladium-catalyzed dearomative conjunctive allylic alkylation (DCAA). These efficient palladium-catalyzed protocols construct the [3.3.1]-bicyclic PPAP core in a single step from their stable aromatic precursors. The first syntheses of 13,14-didehydroxyisogarcinol and garcimultiflorone A stereoisomers are reported in six steps from a commercially available phloroglucinol. Lewis acid-controlled, diastereoselective cationic oxycyclizations enabled asymmetric syntheses of (-)-6-epi-13,14-didehydroxyisogarcinol and (+)-30-epi-13,14-didehydroxyisogarcinol. A similar strategy enabled production of the meso-derived isomers (+/-)-6,30- epi-13,14-didehydroxyisogarcinol and (+/-)-6,30-epi -garcmultiflorone A. A convenient strategy for gram scale synthesis of these stereoisomers was developed utilizing diastereomer separation at a later stage in the synthesis that minimized the number of necessary synthetic operations to access all possible stereoisomers. Finally, we report cationic rearrangements of dearomatized acylphloroglucinols leading to the formation of unprecedented PPAP scaffolds. A novel type A [3.3.1]-bicyclic PPAP was produced as a major product and the structure confirmed by X-ray crystallographic

  16. Cation-pi interaction of the univalent silver cation with meso-octamethylcalix[4]pyrrole: Experimental and theoretical study

    Czech Academy of Sciences Publication Activity Database

    Polášek, Miroslav; Kvíčala, J.; Makrlík, E.; Křížová, Věra; Vaňura, P.

    2017-01-01

    Roč. 1130, FEB 2017 (2017), s. 408-413 ISSN 0022-2860 Grant - others:GA MŠk(CZ) 20/2015; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388955 Keywords : silver cation * meso-octamethylcalix[4]pyrrole * complexation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.753, year: 2016

  17. Voltammetry of Lead Cations on a New Type of Silver Composite Electrode in the Presence of Other Cations

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Šebková, Světlana; Kopanica, M.

    2004-01-01

    Roč. 379, - (2004), s. 294-301 ISSN 1618-2642 Grant - others:GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : voltammetry * silver composite electrode * lead cations Subject RIV: CG - Electrochemistry Impact factor: 2.098, year: 2004

  18. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayss, M. K.; Armentrout, P. B.; Oomens, J.; Schaefer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+,K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD spectra

  19. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayß, M.K.; Armentrout, P.B.; Oomens, J.; Schäfer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+, K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD

  20. The Geometry and Structural Properties of the 4,8,12-Trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene System in the Cationic State. Structures of a Planar Organic Cation with Various Monovalent- and Divalent Anions

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Laursen, Bo W.; Johannsen, Ib

    1999-01-01

    The geometry of the 4,8,12-trioxa-4,8,12,12c- tetrahydrodibenzo[cd,mn]pyrene system in the cationic state was established by X-ray structural resolution of the salts formed between the cationand various anions. The geometry was found to be planar for the 4,8,12-trioxa-4,8,12,12c- tetrahydrodibenzo...... [cd,mn]pyrenylium and 2,6,10-tri (tert-butyl)-4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyre nylium cations with the monovalentanions I-, BF4-, PF6- AsF6-, HNO3. NO3- and CF3SO3-, and the divalent anions S2O62- and Mo6Cl142-. The salts were found to crystallize in distinct space groups...

  1. Synthesis and chemical modification of polymeric resins for the treatment of cations and aromatic hydrocarbons in produced oily water; Sintese de modificacao quimica de resina polimerica e aplicacao na remocao de cations e hidrocarbonetos aromaticos presentes em agua produzida

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, Thiago M.; Rodrigues, Monique F.; Vieira, Helida V.P.; Queiros, Yure G.C.; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas, Lab. de Macromoleculas e Coloides na Industria do Petroleo, Rio de Janeiro, RJ (Brazil)], e-mail: thiagoaversa@ima.ufrj.br

    2011-07-01

    The use of chemically modified resins in oily water treatment process is not very developed yet. Because of this, this work suggests to study the styrene and divinylbenzene sulfonation effect on oil and grease, aniline and calcium removal from the water. The aniline, oils and greases belong to a class of toxic organic compounds, with the Brazilian maximum limits established for disposal in CONAMA 393/2007, while the calcium ions belong to the group of cations of alkaline earth metals which improve hardness to the water, may cause fouling as carbonates and sulfates form. By using sulfonated resins in oily water treatment it is possible to remove not only oils and greases but also calcium and aniline. These kinds of polar compounds are removed because of the cation exchange capacity of resin. (author)

  2. Thermodynamics of the first and second proton dissociations from aqueous L-aspartic acid and L-glutamic acid at temperatures from (278.15 to 393.15) K and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of zwitterionic, protonated cationic, and deprotonated anionic forms at molalities from (0.002 to 1.0) mol . kg{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2007-04-15

    We have measured the densities of aqueous solutions of L-aspartic acid, L-glutamic acid, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15 {<=} T/K {<=} 368.15, at molalities 0.002 {<=} m/mol . kg{sup -1} {<=} 1.0 as solubity of the solutes allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 {<=} T/K {<=} 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V {sub {phi}} and the heat capacities to calculate apparent molar heat capacities C {sub p,{phi}} for these solutions. We used our results and values from the literature for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change {delta}{sub r} C {sub p,m}(T, m) for ionization of water to calculate parameters for {delta}{sub r} C {sub p,m}(T, m) for the first two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young's Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m). This procedure gave parameters for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for L-aspartinium and L-glutaminium chlorides and for monosodium L-aspartate and L-glutamate which modeled our observed results within experimental uncertainties. We report values for {delta}{sub r} C {sub p,m}, {delta}{sub r} H {sub m}, pQ {sub a}, {delta}{sub r} S {sub m}, and {delta}{sub r} V {sub m} for the first and second proton dissociations from protonated aqueous L-aspartic acid and L-glutamic acid as functions of T and m.

  3. Cation Exchange Efficiency Of Modified Bentonite Using In-Situ GAMMA Radiation Polymerization Of Acrylic Acid Or Acrylamide

    International Nuclear Information System (INIS)

    ISMAIL, S.A.; FALAZI, B.

    2009-01-01

    Modified bentonites as cation exchangers were prepared by treating raw bentonite with 3N NaOH at 95 0 C followed by in-situ polymerization using gamma irradiation as well as hydrogen peroxide initiation of acrylic acid or acrylamide in the matrix.Water swelling and acid capacity were determined and cation exchange capacity for Cu 2+ , Ni 2+ and Co 2+ was evaluated. It has been found that catiexchange capacity of treated bentonite was increased as result of formed polyacrylic acid and polyacrylamide in the matrix. In case of acrylic acid, the maximum cation exchange capacities of 3.5, 3.1 and 2.5 mg equivalent/g were determined for Cu 2+ , Ni 2+ and Co 2+ , respectively, and for acrylamide, the corresponding capacities were 2.9, 2.8 and 2.6 mg equivalent/g, respectively. Water swelling was found to be associated with holding large amounts of water, for instance, 49 g of water was sorbed per one gram of the sodium salt form of polyacrylic acid in bentonite matrix, in other words the degree of swelling in water achieved 4500%.

  4. Effect of cation competition on cadmium uptake from solution by the earthworm Eisenia fetida.

    NARCIS (Netherlands)

    Li, L.-Z.; Zhou, D.-M.; Wang, P.; Jin, S.-Y.; Peijnenburg, W.J.G.M.; Reinecke, A.J.; van Gestel, C.A.M.

    2009-01-01

    Metal speciation alone is insufficient to predict metal accumulation in aquatic and terrestrial organisms, because competition between cations can play an important role. In the present study, the effects of competing cations (Ca

  5. Behavior of cationic, anionic and colloidal species of titanium, zirconium and thorium in presence of ion exchange resins

    International Nuclear Information System (INIS)

    Souza Filho, G. de; Abrao, A.

    1976-01-01

    The distribution of titanium, zirconium and thorium is aqueous and resin phases has been studied using strong cationic resin in the R-NH 4 form. Solutions of the above elements in perchloric, nitric, hydrochloric and suphuric media were used. Each set of experiments was made by separately varying one of the five parameters - type of anion present, acidity of solution, temperature of percolation, age of solution and concentration of the element. It was found that, depending on the particular balance of these parameters, the elements investigated may be found in acidic solutions either as cationic, anionic or colloidal species. It is emphasized that the colloidal species of titanium, zirconium or thorium are not retained by the ion exchangers, and from this property a method for the separation and purification of the above elements has been outlined [pt

  6. A cation-π interaction at a phenylalanine residue in the glycine receptor binding site is conserved for different agonists

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Hanek, Ariele P; Price, Kerry L

    2011-01-01

    . In the current study, we investigated whether the lower efficacy agonists of the human GlyR β-alanine and taurine also form cation-π interactions with Phe159. By incorporating a series of unnatural amino acids, we found cation-π interactions between Phe159 and the amino groups of β-alanine and taurine....... The strengths of these interactions were significantly weaker than for glycine. Modeling studies suggest that β-alanine and taurine are orientated subtly differently in the binding pocket, with their amino groups further from Phe159 than that of glycine. These data therefore show that similar agonists can have...... similar but not identical orientations and interactions in the binding pocket and provide a possible explanation for the lower potencies of β-alanine and taurine....

  7. The thermodynamic stability of hydrogen bonded and cation bridged complexes of humic acid models-A theoretical study

    International Nuclear Information System (INIS)

    Aquino, Adelia J.A.; Tunega, Daniel; Pasalic, Hasan; Haberhauer, Georg; Gerzabek, Martin H.; Lischka, Hans

    2008-01-01

    Hydrogen bonded and cation bridged complexation of poly(acrylic acid) oligomers, representing a model compound for humic acids, with acetic acid and the herbicide (4-chloro-2-methylphenoxy) acetic acid (MCPA) have been studied by means of density functional theory. Solvation effects were computed by means of a combination of microsolvation (explicit insertion of water molecules) and global solvation (polarizable continuum approach). The stability of hydrogen bonded complexes in solution is characterized by a strong competition between solute and solvent molecules. The cation bridged complexes of the negatively charged (deprotonated) ligands were found to be strongly favored explaining the capability of humic acids to fixate anionic species from soil solutions and the ability to form cross-linking structures within the humic acid macromolecules

  8. Extraction and characterization of ternary complexes between natural organic matter, cations, and oxyanions from a natural soil.

    Science.gov (United States)

    Peel, Hannah R; Martin, David P; Bednar, Anthony J

    2017-06-01

    Natural organic matter (NOM) can have a significant influence on the mobility and fate of inorganic oxyanions, such as arsenic and selenium, in the environment. There is evidence to suggest that interactions between NOM and these oxyanions are facilitated by bridging cations (primarily Fe 3+ ) through the formation of ternary complexes. Building on previous work characterizing ternary complexes formed in the laboratory using purified NOM, this study describes the extraction and characterization of intact ternary complexes directly from a soil matrix. The complexes are stable to the basic extraction conditions (pH 12) and do not appear to change when the pH of the extract is adjusted back to neutral. The results suggest that ternary complexes between NOM, cations, and inorganic oxyanions exist in natural soils and could play a role in the speciation of inorganic oxyanions in environmental matrices. Published by Elsevier Ltd.

  9. Exploration of overloaded cation exchange chromatography for monoclonal antibody purification.

    Science.gov (United States)

    Liu, Hui F; McCooey, Beth; Duarte, Tiago; Myers, Deanna E; Hudson, Terry; Amanullah, Ashraf; van Reis, Robert; Kelley, Brian D

    2011-09-28

    Cation exchange chromatography using conventional resins, having either diffusive or perfusive flow paths, operated in bind-elute mode has been commonly employed in monoclonal antibody (MAb) purification processes. In this study, the performance of diffusive and perfusive cation exchange resins (SP-Sepharose FF (SPSFF) and Poros 50HS) and a convective cation exchange membrane (Mustang S) and monolith (SO(3) Monolith) were compared. All matrices were utilized in an isocratic state under typical binding conditions with an antibody load of up to 1000 g/L of chromatographic matrix. The dynamic binding capacity of the cation exchange resins is typically below 100 g/L resin, so they were loaded beyond the point of anticipated MAb break through. All of the matrices performed similarly in that they effectively retained host cell protein and DNA during the loading and wash steps, while antibody flowed through each matrix after its dynamic binding capacity was reached. The matrices differed, though, in that conventional diffusive and perfusive chromatographic resins (SPSFF and Poros 50HS) demonstrated a higher binding capacity for high molecular weight species (HMW) than convective flow matrices (membrane and monolith); Poros 50HS displayed the highest HMW binding capacity. Further exploration of the conventional chromatographic resins in an isocratic overloaded mode demonstrated that the impurity binding capacity was well maintained on Poros 50HS, but not on SPSFF, when the operating flow rate was as high as 36 column volumes per hour. Host cell protein and HMW removal by Poros 50HS was affected by altering the loading conductivity. A higher percentage of host cell protein removal was achieved at a low conductivity of 3 mS/cm. HMW binding capacity was optimized at 5 mS/cm. Our data from runs on Poros 50HS resin also showed that leached protein A and cell culture additive such as gentamicin were able to be removed under the isocratic overloaded condition. Lastly, a MAb

  10. Complexation as an approach to entrap cationic drugs into cationic nanoparticles administered intranasally for Alzheimer's disease management: preparation and detection in rat brain.

    Science.gov (United States)

    Hanafy, Amira S; Farid, Ragwa M; ElGamal, Safaa S

    2015-01-01

    Complexation was investigated as an approach to enhance the entrapment of the cationic neurotherapeutic drug, galantamine hydrobromide (GH) into cationic chitosan nanoparticles (CS-NPs) for Alzheimer's disease management intranasally. Biodegradable CS-NPs were selected due to their low production cost and simple preparation. The effects of complexation on CS-NPs physicochemical properties and uptake in rat brain were examined. Placebo CS-NPs were prepared by ionic gelation, and the parameters affecting their physicochemical properties were screened. The complex formed between GH and chitosan was detected by the FT-IR study. GH/chitosan complex nanoparticles (GH-CX-NPs) were prepared by ionic gelation, and characterized in terms of particle size, zeta potential, entrapment efficiency, in vitro release and stability for 4 and 25 °C for 3 months. Both placebo CS-NPs and GH-CX-NPs were visualized by transmission electron microscopy. Rhodamine-labeled GH-CX-NPs were prepared, administered to male Wistar rats intranasally, and their delivery to different brain regions was detected 1 h after administration using fluorescence microscopy and software-aided image processing. Optimized placebo CS-NPs and GH-CX-NPs had a diameter 182 and 190 nm, and a zeta potential of +40.4 and +31.6 mV, respectively. GH encapsulation efficiency and loading capacity were 23.34 and 9.86%, respectively. GH/chitosan complexation prolonged GH release (58.07% ± 6.67 after 72 h), improved formulation stability at 4 °C in terms of drug leakage and particle size, and showed insignificant effects on the physicochemical properties of the optimized placebo CS-NPs (p > 0.05). Rhodamine-labeled GH-CX-NPs were detected in the olfactory bulb, hippocampus, orbitofrontal and parietal cortices. Complexation is a promising approach to enhance the entrapment of cationic GH into the CS-NPs. It has insignificant effect on the physicochemical properties of CS-NPs. GH-CX-NPs were successfully

  11. Pentachlorophenol radical cations generated on Fe(III)-montmorillonite initiate octachlorodibenzo-p-dioxin formation in clays: DFT and FTIR studies

    Science.gov (United States)

    Gu, Cheng; Liu, Cun; Johnston, Cliff T.; Teppen, Brian J.; Li, Hui; Boyd, Stephen A.

    2011-01-01

    Octachlorodibenzodioxin (OCDD) forms spontaneously from pentachlorophenol (PCP) on the surfaces of Fe(III)-saturated smectite clay (1). Here, we used in situ FTIR methods and quantum mechanical calculations to determine the mechanism by which this reaction is initiated. As the clay was dehydrated, vibrational spectra showed new peaks that grew and then reversibly disappeared as the clay rehydrated. First principle DFT calculations of hydrated Fe-PCP clusters reproduced these transient FTIR peaks when inner-sphere complexation and concomitant electron transfer produced Fe(II) and PCP radical cations. Thus, our experimental (FTIR) and theoretical (quantum mechanical) results mutually support the hypothesis that OCDD formation on Fe-smectite surfaces is initiated by the reversible formation of metastable PCP radical cations via single electron transfer from PCP to Fe(III). The negatively charged clay surface apparently selects for this reaction mechanism by stabilizing PCP radical cations. PMID:21254769

  12. Esterification of palm fatty acid distillate with epychlorohydrin using cation exchange resin catalyst

    Science.gov (United States)

    Budhijanto, Budhijanto; Subagyo, Albertus F. P. H.

    2017-05-01

    Palm Fatty Acid Distillate (PFAD) is one of the wastes from the conversion of crude palm oil (CPO) into cooking oil. The PFAD is currently only utilized as the raw material for low grade soap and biofuel. To improve the economic value of PFAD, it was converted into monoglyceride by esterification process. Furthermore, the monoglyceride could be polymerized to form alkyd resin, which is a commodity of increasing importance. This study aimed to propose a kinetics model for esterification of PFAD with epichlorohydrin using cation exchange resin catalyst. The reaction was the first step from a series of reactions to produce the monoglyceride. In this study, the reaction between PFAD and epichlorohydirne was run in a stirred batch reactor. The stirrer was operated at a constant speed of 400 RPM. The reaction was carried out for 180 minutes on varied temperatures of 60°C, 70°C, 80°C, dan 90°C. Cation exchange resin was applied as solid catalysts. Analysis was conducted periodically by measuring the acid number of the samples, which was further used to calculate PFAD conversion. The data were used to determine the rate constants and the equilibrium constants of the kinetics model. The kinetics constants implied that the reaction was reversible and controlled by the intrinsic surface reaction. Despite the complication of the heterogeneous nature of the reaction, the kinetics data well fitted the elementary rate law. The effect of temperature on the equilibrium constants indicated that the reaction is exothermic.

  13. Discovery of the Ubiquitous Cation NS+ in Space Confirmed by Laboratory Spectroscopy

    Science.gov (United States)

    Cernicharo, J.; Lefloch, B.; Agúndez, M.; Bailleux, S.; Margulès, L.; Roueff, E.; Bachiller, R.; Marcelino, N.; Tercero, B.; Vastel, C.; Caux, E.

    2018-02-01

    We report the detection in space of a new molecular species that has been characterized spectroscopically and fully identified from astrophysical data. The observations were carried out with the IRAM 30 m telescope. The molecule is ubiquitous as its J=2\\to 1 transition has been found in cold molecular clouds, prestellar cores, and shocks. However, it is not found in the hot cores of Orion-KL and in the carbon-rich evolved star IRC+10216. Three rotational transitions in perfect harmonic relation J\\prime =2/3/5 have been identified in the prestellar core B1b. The molecule has a 1Σ electronic ground state and its J=2\\to 1 transition presents the hyperfine structure characteristic of a molecule containing a nucleus with spin 1. A careful analysis of possible carriers shows that the best candidate is NS+. The derived rotational constant agrees within 0.3%–0.7% with ab initio calculations. NS+ was also produced in the laboratory to unambiguously validate the astrophysical assignment. The observed rotational frequencies and determined molecular constants confirm the discovery of the nitrogen sulfide cation in space. The chemistry of NS+ and related nitrogen-bearing species has been analyzed by means of a time-dependent gas-phase model. The model reproduces well the observed NS/NS+ abundance ratio, in the range 30–50, and indicates that NS+ is formed by reactions of the neutral atoms N and S with the cations SH+ and NH+, respectively.

  14. Effect of hafnium addition on solidifi cation structure of cast Ti-46Al alloys

    Directory of Open Access Journals (Sweden)

    Su Yanqing

    2008-11-01

    Full Text Available To investigate the effect of hafnium addition on the solidifi cation structure, Ti-46Al alloys with nominal compositions of Ti-46Al-xHf (x = 0, 3, 5, 7 (at.% were arc-melted into small ingots in an argon atmosphere. The characteristics of the macrostructures and microstructures were studied using a linear intercept method, OM, SEM (BSE, XRD and TEM. The results showed that the ingots with Hf have near lamellar microstructure in columnar and dendrite morphology. The hafnium concentration has a strong effect on the columnar spacing refi nement. Increasing Hf from 0 to 7 (at.%, the columnar spacing can be reduced from ~ 1000 to ~ 400 μm. Constitute phases of the ingots are α2, a small amount of B2 and c. Most of the B2 phases, richer in Hf and leaner in Al and Ti, exist on the node of the dendrite core in block shape and a little across the lamellar colonies in stick shape. The c phases exist on the boundaries of lamellar colonies in small cellular shape. There also exists a segregation of Hf on the columnar and dendrite core. Particularly, both the α- and β-phase form from the melt as prior phases. The possible phase sequencing during solidifi cation and solid-state transformations with Hf is given in this paper.

  15. Dendritic cationic lipids with highly charged headgroups for efficient gene delivery.

    Science.gov (United States)

    Ewert, Kai K; Evans, Heather M; Bouxsein, Nathan F; Safinya, Cyrus R

    2006-01-01

    Gene therapy is expected to lead to powerful new approaches for curing many diseases, a potential that is currently explored in worldwide clinical trials. Nonviral DNA delivery systems are desirable to overcome the inherent problems of viral vectors, but their current efficiency requires improvement and the understanding of their mechanism of action is incomplete. We have synthesized new multivalent cationic lipids with highly charged dendritic headgroups to probe the structure-transfection efficiency relationships of cationic liposome (CL)-DNA complexes, a prevalent nonviral vector. The lipid headgroups are constructed from ornithine cores and ornithine or carboxyspermine endgroups. The dendritic lipids were prepared on a gram scale, using a synthetic scheme that permits facile variation of the lipid building blocks headgroup, spacer, and hydrophobic moiety. They carry four to sixteen positive charges in their headgroups. Complexes of DNA with mixtures of the dendritic lipids and neutral 1,2-dioleoyl-sn-glycero phosphatidylcholine (DOPC) exhibit novel structures at high contents of the highly charged lipids, while the well-known lamellar phase is formed at high contents of DOPC. DNA complexes of the new dendritic lipids efficiently transfect mammalian cells in culture without cytotoxicity and, in contrast to lamellar complexes, maintain high transfection efficiency over a broad range of composition.

  16. Observation of water separated ion-pairs between cations and phospholipid headgroups.

    Science.gov (United States)

    van der Post, Sietse T; Hunger, Johannes; Bonn, Mischa; Bakker, Huib J

    2014-04-24

    In this work, we present evidence for ion pair formation of cations with a high surface charge density (Na(+) and Ca(2+)) and phosphate groups of phospholipids. We used femto-second infrared pump-probe and dielectric spectroscopy to probe the dynamics of water molecules in solutions of phosphorylethanolamine and different types of cations. We find that sodium and calcium cooperatively retard the dynamics of water in solutions of phosphorylethanolamine, implying the formation of solvent separated ion pairs. This ion-specific interaction is absent for potassium, cesium and ammonium. We compare our results to dielectric spectroscopy experiments, which probes the rotation of all dipolar molecules and ions in solution. The rotation of the dipolar phosphorylethanolamine ion shows that long-lived ion-pairs are only formed with calcium and not with ammonium, cesium, potassium, and sodium. This finding implies that the association between calcium and the phosphate is strong with lifetimes exceeding 200 ps, while the interaction with sodium is relatively short-lived (∼20-100 ps).

  17. Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites.

    Science.gov (United States)

    Wang, Miao; Olszewska, Anna; Walther, Andreas; Malho, Jani-Markus; Schacher, Felix H; Ruokolainen, Janne; Ankerfors, Mikael; Laine, Janne; Berglund, Lars A; Osterberg, Monika; Ikkala, Olli

    2011-06-13

    We present a facile ionic assembly between fibrillar and spherical colloidal objects toward biomimetic nanocomposites with majority hard and minority soft domains based on anionic reinforcing native cellulose nanofibrils and cationic amphiphilic block copolymer micelles with rubbery core. The concept is based on ionic complexation of carboxymethylated nanofibrillated cellulose (NFC, or also denoted as microfibrillated cellulose, MFC) and micelles formed by aqueous self-assembly of quaternized poly(1,2-butadiene)-block-poly(dimethylaminoethyl methacrylate) with high fraction of the NFC reinforcement. The adsorption of block copolymer micelles onto nanocellulose is shown by quartz crystal microbalance measurements, atomic force microscopy imaging, and fluorescent optical microscopy. The physical properties are elucidated using electron microscopy, thermal analysis, and mechanical testing. The cationic part of the block copolymer serves as a binder to NFC, whereas the hydrophobic rubbery micellar cores are designed to facilitate energy dissipation and nanoscale lubrication between the NFC domains under deformation. We show that the mechanical properties do not follow the rule of mixtures, and synergistic effects are observed with promoted work of fracture in one composition. As the concept allows wide possibilities for tuning, the work suggests pathways for nanocellulose-based biomimetic nanocomposites combining high toughness with stiffness and strength.

  18. Aromatic substitution in the gas phase. Alkylation of arenes by gaseous C4H9+ cations

    International Nuclear Information System (INIS)

    Cacace, F.; Ciranni, G.; Giacomello, P.

    1981-01-01

    Butyl cations, obtained in the dilute gas state from the radiolysis of butane in the pressure range from 70 to 750 torr, have been allowed to react with benzene, toluene, and their mixtures or with trace amounts of o-xylene in the gaseous system. The gas-phase butylation yields invariably sec-butylarenes, remarkably free of isomeric byproducts, namely n- and tert-butylarenes. Other alkylation experiments, where gaseous butyl cations from the reaction of butane with radiolytically formed H 3 + ions were used as reagent, confirmed the exclusive formation of sec-butylarenes. The butylation process displays the positional and substrate selectivity and the dependence of orientation on the pressure of the system, typical of other gas-phase ionic substitutions. At high pressures, orth-para orientation predominates in the sec-butylation of toluene, with a ortho:meta:para ratio of 43:30:27 at 715 torr. As the pressure is reduced, a gradual shift in favor of the thermodynamically most stable meta-substituted arenium ion is observed, leading to a ortho:meta:para ratio of 31:48:21 at 70 torr

  19. How Native and Alien Metal Cations Bind ATP: Implications for Lithium as a Therapeutic Agent

    Science.gov (United States)

    Dudev, Todor; Grauffel, Cédric; Lim, Carmay

    2017-02-01

    Adenosine triphosphate (ATP), the major energy currency of the cell, exists in solution mostly as ATP-Mg. Recent experiments suggest that Mg2+ interacts with the highly charged ATP triphosphate group and Li+ can co-bind with the native Mg2+ to form ATP-Mg-Li and modulate the neuronal purine receptor response. However, it is unclear how the negatively charged ATP triphosphate group binds Mg2+ and Li+ (i.e. which phosphate group(s) bind Mg2+/Li+) and how the ATP solution conformation depends on the type of metal cation and the metal-binding mode. Here, we reveal the preferred ATP-binding mode of Mg2+/Li+ alone and combined: Mg2+ prefers to bind ATP tridentately to each of the three phosphate groups, but Li+ prefers to bind bidentately to the terminal two phosphates. We show that the solution ATP conformation depends on the cation and its binding site/mode, but it does not change significantly when Li+ binds to Mg2+-loaded ATP. Hence, ATP-Mg-Li, like Mg2+-ATP, can fit in the ATP-binding site of the host enzyme/receptor, activating specific signaling pathways.

  20. Novel gramicidin formulations in cationic lipid as broad-spectrum microbicidal agents

    Directory of Open Access Journals (Sweden)

    Ragioto DA

    2014-06-01

    Full Text Available Danielle AMT Ragioto, Letícia DM Carrasco, Ana M Carmona-Ribeiro Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil Abstract: Dioctadecyldimethylammonium bromide (DODAB is an antimicrobial lipid that can be dispersed as large closed bilayers (LV or bilayer disks (BF. Gramicidin (Gr is an antimicrobial peptide assembling as channels in membranes and increasing their permeability towards cations. In mammalian cells, DODAB and Gr have the drawbacks of Gram-positive resistance and high toxicity, respectively. In this study, DODAB bilayers incorporating Gr showed good antimicrobial activity and low toxicity. Techniques employed were spectroscopy, photon correlation spectroscopy for sizing and evaluation of the surface potential at the shear plane, turbidimetric detection of dissipation of osmotic gradients in LV/Gr, determination of bacterial cell lysis, and counting of colony-forming units. There was quantitative incorporation of Gr and development of functional channels in LV. Gr increased the bilayer charge density in LV but did not affect the BF charge density, with localization of Gr at the BF borders. DODAB/Gr formulations substantially reduce Gr toxicity against eukaryotic cells and advantageously broaden the antimicrobial activity spectrum, effectively killing Escherichia coli and Staphylococcus aureus bacteria with occurrence of cell lysis. Keywords: antimicrobial peptides, cationic bilayers, bilayer fragments, dioctadecyldimethylammonium bromide, gramicidin A, self-assembly

  1. Microwave-assisted cationic polymerization of palm olein and their urea inclusion products

    Science.gov (United States)

    Soegijono, Bambang; Farid, Muhamad; Alim Mas’ud, Zainal

    2018-01-01

    Cationic polymerization is affected by the relative amount of unsaturated bond (C=C) in the compound. The enrichment of an unsaturated triglyceride fraction from oils may be performed using urea inclusion techniques. In this study, palm olein was enriched-unsaturated fraction using urea-methanol system. The palm olein and its urea-inclusion products were cationic polymerized with ethereal boron trifluoride catalyst and followed by irradiation using a commercial microwave (microwave-assisted). The microwave irradiated products were cured at 110 °C for 24 hours. Fatty acid composition of the palm olein and its urea-inclusion products were analyzed by gas chromatography. Iodine numbers, functional groups, and ultraviolet absorption spectra of all palm olein origin, urea inclusion products and polymerization products were analyzed using titrimetric, ultraviolet spectrophotometric, and Fourier Transform infrared spectrophotometric methods. Differential scanning calorimetric (DSC) was used to observe the thermal characteristics of the polymer. Urea-inclusion process increased the unsaturated fatty acid components as indicated by the increased iodine number, intensity of alkene band absorptions in the infrared spectra, and the absorbance of the ultraviolet spectra. The polymer formation is converting the C=C group to C-C, which is indicated by the opposite of the urea inclusion process. The curing process results in reformation of new C=C bonds that were similar to that of the urea inclusion process. The DSC thermogram curve shows that the enrichment process improves the thermal stability of the polymer formed.

  2. Multidimensional Perovskites: A Mixed Cation Approach Towards Ambient Stable and Tunable Perovskite Photovoltaics.

    Science.gov (United States)

    Koh, Teck Ming; Thirumal, Krishnamoorthy; Soo, Han Sen; Mathews, Nripan

    2016-09-22

    Although halide perovskites are able to deliver high power conversion efficiencies, their ambient stability still remains an obstacle for commercialization. Thus, promoting the ambient stability of perovskites has become a key research focus. In this review, we highlight the sources of instability in conventional 3 D perovskites, including water intercalation, ion migration, and thermal decomposition. Recently, the multidimensional perovskites approach has become one of the most promising strategies to enhance the stability of perovskites. As compared to pure 2 D perovskites, multidimensional perovskites typically possess more ideal band gaps, better charge transport, and lower exciton binding energy, which are essential for photovoltaic applications. The larger organic cations in multidimensional perovskites could also be more chemically stable at higher temperatures than the commonly used methylammonium cation. By combining 3 D and 2 D perovskites to form multidimensional perovskites, halide perovskite photovoltaics can attain both high efficiency and increased stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Lipofectamine and related cationic lipids strongly improve adenoviral infection efficiency of primitive human hematopoietic cells.

    Science.gov (United States)

    Byk, T; Haddada, H; Vainchenker, W; Louache, F

    1998-11-20

    Adenoviral vectors have the potential to infect a large number of cell types including quiescent cells. Their use in hematopoietic cells is limited by the episomal form of their DNA, leading to transgene loss in the progeny cells. However, the use of this vector may be interesting for short-term in vitro modifications of primitive human hematopoietic cells. Therefore, we have investigated the ability of adenovirus to transduce cord blood CD34+ cells. Several promoters were tested using the lacZ reporter gene. The PGK and CMV promoters induced transgene expression in 18-25% of the cells, whereas the HTLV-I and especially the RSV promoter were almost inactive. To improve infection efficiency, adenovirus was complexed with cationic lipids. Lipofectamine, Cellfectin, and RPR120535b, but not Lipofectin, Lipofectace, or DOTAP, markedly improved transgene expression in CD34+ cells (from 19 to 35%). Lipofectamine strongly enhanced infection efficiency of the poorly infectable primitive CD34+CD38low cells (from 11 to 28%) whereas the more mature CD34+CD38+ cells were only slightly affected (from 24 to 31%). Lipofectamine tripled the infection of CFU-GMs and LTC-ICs derived from the CD34+CD38low cell fraction (from 4 to 12% and from 5 to 16%, respectively) and doubled that of BFU-Es (from 13 to 26%). We conclude that cationic lipids can markedly increase the efficiency of adenovirus-mediated gene transfer into primitive hematopoietic cells.

  4. Templated preparation of porous magnetic microspheres and their application in removal of cationic dyes from wastewater.

    Science.gov (United States)

    Liu, Qingquan; Wang, Li; Xiao, Anguo; Gao, Jingming; Ding, Wenbing; Yu, Haojie; Huo, Jia; Ericson, Mårten

    2010-09-15

    Porous magnetic microspheres with large particle size (350-450 microm) were prepared with sulfonated macroporous polydivinylbenzene as a template. The preparation process included ferrous ion exchange and following oxidation by hydrogen peroxide. The results showed that the weight fraction of magnetic nanoparticles exceeded 20 wt% in microspheres after the preparation process was repeated three times. X-ray diffraction profiles indicated that the crystalline phase of as-formed magnetic nanoparticles was magnetite (Fe(3)O(4)). TEM images revealed rod-like magnetite crystal after the first oxidation cycle, however, the crystal morphologies were transferred into random shape after more oxidation cycles. The applicability of porous magnetic microspheres for removal of cationic dyes from water was also explored. The results exhibited that basic fuchsin and methyl violet could be quickly removed from water with high efficiency. More importantly, the magnetic microspheres could be easily regenerated and repeatedly employed for wastewater treatment. Therefore, a novel methodology was provided for fast removal cationic dyes from wastewater. Copyright 2010 Elsevier B.V. All rights reserved.

  5. Activation of divalent cation influx into S. cerevisiae cells by hypotonic downshift.

    Science.gov (United States)

    Beeler, T; Gable, K; Dunn, T

    1997-11-01

    Subjecting Saccharomyces cerevisiae cells to a hypotonic downshift by transferring cells form YPD medium containing 0.8 M sorbitol to YPD medium without sorbitol induces a transient rapid influx of Ca2+ and other divalent cations into the cell. For cells grown in YPD at 37 degrees C, this hypotonic downshift increases Ca2+ accumulation 6.7-fold. Hypotonic downshift-induced Ca2+ accumulation and steady-state Ca2+ accumulation in isotonic YPD medium are differentially affected by dodecylamine and Mg2+. The Ca(2+)-influx pathway responsible for hypotonic-induced Ca2+ influx may account for about 10-35% of Ca2+ accumulation by cells growing in YPD. Ca2+ influx is not required for cells to survive a hypotonic downshift. Hypotonic downshift greatly reduces the ability of S. cerevisiae cells to survive a 5-min exposure to 10 mM Cd2+ suggesting that mutants resistant to acute Cd2+ exposure may help identify genes required for hypotonic downshift-induced divalent cation influx.

  6. Spectroscopic and computer modelling studies of mixed-cation superionic fluorites

    CSIR Research Space (South Africa)

    Netshisaulu, TT

    2005-10-19

    Full Text Available into the local environments of the Cd and Pb cations (as a function of composition and temperature) in CdF2 (xPbF(2)) mixed-cation superionic fluorites. A high degree of disorder is shown around both cations. However, the extent of disorder is even larger around...

  7. Gene vectors based on DOEPC/DOPE mixed cationic liposomes : a physicochemical study

    NARCIS (Netherlands)

    Munoz-Ubeda, Monica; Rodriguez-Pulido, Alberto; Nogales, Aurora; Llorca, Oscar; Quesada-Perez, Manuel; Martin-Molina, Alberto; Aicart, Emilio; Junquera, Elena

    2011-01-01

    A double approach, experimental and theoretical, has been followed to characterize from a physicochemical standpoint the compaction process of DNA by means of cationic colloidal aggregates. The colloidal vectors are cationic liposomes constituted by a mixture of a novel cationic lipid,

  8. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Science.gov (United States)

    2010-04-01

    ... adhesive. 872.3480 Section 872.3480 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended to...

  9. Comparison between paricalcitol and active non-selective vitamin D receptor activator for secondary hyperparathyroidism in chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Cai, Panpan; Tang, Xiaohong; Qin, Wei; Ji, Ling; Li, Zi

    2016-04-01

    The goal of this systematic review is to evaluate the efficacy and safety of paricalcitol versus active non-selective vitamin D receptor activators (VDRAs) for secondary hyperparathyroidism (SHPT) management in chronic kidney disease (CKD) patients. PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), clinicaltrials.gov (inception to September 2015), and ASN Web site were searched for relevant studies. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of paricalcitol and active non-selective VDRA in adult CKD patients with SHPT was performed using Review Manager 5.2. A total of 10 trials involving 734 patients were identified for this review. The quality of included trials was limited, and very few trials reported all-cause mortality or cardiovascular calcification without any differences between two groups. Compared with active non-selective VDRAs, paricalcitol showed no significant difference in both PTH reduction (MD -7.78, 95% CI -28.59-13.03, P = 0.46) and the proportion of patients who achieved the target reduction of PTH (OR 1.27, 95% CI 0.87-1.85, P = 0.22). In addition, no statistical differences were found in terms of serum calcium, episodes of hypercalcemia, serum phosphorus, calcium × phosphorus products, and bone metabolism index. Current evidence is insufficient, showing paricalcitol is superior to active non-selective VDRAs in lowering PTH or reducing the burden of mineral loading. Further trials are required to prove the tissue-selective effect of paricalcitol and to overcome the limitation of current research.

  10. Intense pseudotransport of a cationic drug mediated by vacuolar ATPase: Procainamide-induced autophagic cell vacuolization

    International Nuclear Information System (INIS)

    Morissette, Guillaume; Lodge, Robert; Marceau, Francois

    2008-01-01

    Cationic drugs frequently exhibit large apparent volumes of distribution, consistent with various forms of cellular sequestration. The contributions of organelles and metabolic processes that may mimic drug transport were defined in human vascular smooth muscle cells. We hypothesized that procainamide-induced vacuolar cytopathology is driven by intense pseudotransport mediated by the vacuolar (V)-ATPase and pursued the characterization of vesicular trafficking alterations in this model. Large amounts of procainamide were taken up by intact cells (maximal in 2 h, reversible upon washout, apparent K M 4.69 mM; fluorometric determination of cell-associated drug). Procainamide uptake was extensively prevented or reversed by pharmacological inhibition of the V-ATPase with bafilomycin A1 or FR 167356, decreased at low extracellular pH and preceded vacuolar cell morphology. However, the uptake of procainamide was unaffected by mitochondrial poisons that reduced the uptake of rhodamine 6G. Large vacuoles induced by millimolar procainamide were labeled with the late endosome/lysosome markers Rab7 and CD63 and the autophagy effector LC3; their osmotic formation (but not procainamide uptake) was reduced by extracellular mannitol and parallel to LC3 II formation. Procainamide-induced vacuolization is associated with defective endocytosis of fluorophore-labeled bovine serum albumin, but not with induction of the unfolded protein response. The contents of a vacuole subset slowly (≥ 24 h) become positive for Nile red staining (phospholipidosis-like response). V-ATPase-driven ion trapping is a form of intense cation pseudotransport that concerns the uncharged form of the drugs, and is associated with a vacuolar, autophagic and evolutive cytopathology and profound effects on vesicular trafficking

  11. High-dynamic-range cationic two-photon photopolymerization

    Science.gov (United States)

    Boiko, Yuri B.; Costa, Joannes M.; Wang, Mark M.; Esener, Sadik C.

    2001-06-01

    Cationic-induced two-photon photopolymerization is demonstrated at 710 nm, using an isopropylthioxanthone/diarylidonium salt initiating system for the cationic polymerization of an epoxide. The polymerization threshold J2th is found to be approximately 1 GW/cm2, with a dynamic range of > 100, i.e. the material can be fully polymerized at intensities > 100 times the threshold level without damage. The polymerization rate R is found to be proportional to the m equals 1.7 power of the intensity, or R equals [C (J-J2th)]m equals [C (J-J2th)]1.7, which implies a significantly stronger localization of the photochemical response than that of free radical photoinitiators. R and J2th significantly improve when the concentration z of the initiator (onium salt) increases.

  12. Mass analyzed threshold ionization spectroscopy of 1-methylindole cation

    Science.gov (United States)

    Lin, Jung Lee; Tzeng, Wen Bih

    2003-08-01

    The vibrationally resolved mass analyzed threshold ionization spectra of jet-cooled 1-methylindole (1MI) have been recorded by ionizing via four vibronic levels. The adiabatic ionization energy of this molecule is determined to be 60 749 ± 5 cm -1, which is less than that of indole by 1842 cm -1. This indicates that the N-methyl substitution causes a greater extent of the lowering in the zero energy level of the cationic ground state than that of the neutral. A few characteristic vibrations of the 1MI cation are observed, where the frequencies of the out-of-plane, in-plane bending and stretching vibrations of the N-CH 3 part are found to be 124, 251, and 1492 cm -1, respectively.

  13. Exchangeable cations in some soils of Mt. Stara planina

    Directory of Open Access Journals (Sweden)

    Belanović Snežana

    2005-01-01

    Full Text Available Land use in forest and pasture ecosystems requires the respecting of ecological and economic interactions between the individual components of these ecosystems. The content of nutrition elements in the soil solution depends on soil types, climate conditions and vegetation species, i.e., it is conditioned by their cycling in the ecosystem. This paper studies the cation exchange capacity in pasture and forest soils of Mt. Stara Planina.

  14. Cation-Exchanged Zeolitic Chalcogenides for CO2 Adsorption.

    Science.gov (United States)

    Yang, Huajun; Luo, Min; Chen, Xitong; Zhao, Xiang; Lin, Jian; Hu, Dandan; Li, Dongsheng; Bu, Xianhui; Feng, Pingyun; Wu, Tao

    2017-12-18

    We report here the intrinsic advantages of a special family of porous chalcogenides for CO 2 adsorption in terms of high selectivity of CO 2 /N 2 , large uptake capacity, and robust structure due to their first-ever unique integration of the chalcogen-soft surface, high porosity, all-inorganic crystalline framework, and the tunable charge-to-volume ratio of exchangeable cations. Although tuning the CO 2 adsorption properties via the type of exchangeable cations has been well-studied in oxides and MOFs, little is known about the effects of inorganic exchangeable cations in porous chalcogenides, in part because ion exchange in chalcogenides can be very sluggish and incomplete due to their soft character. We have demonstrated that, through a methodological change to progressively tune the host-guest interactions, both facile and nearly complete ion exchange can be accomplished. Herein, a series of cation-exchanged zeolitic chalcogenides (denoted as M@RWY) were studied for the first time for CO 2 adsorption. Samples were prepared through a sequential ion-exchange strategy, and Cs + -, Rb + -, and K + -exchanged samples demonstrated excellent CO 2 adsorption performance. Particularly, K@RWY has the superior CO 2 /N 2 selectivity with the N 2 adsorption even undetected at either 298 or 273 K. It also has the large uptake of 6.3 mmol/g (141 cm 3 /g) at 273 K and 1 atm with an isosteric heat of 35-41 kJ mol -1 , the best among known porous chalcogenides. Moreover, it permits a facile regeneration and exhibits an excellent recyclability, as shown by the multicycling adsorption experiments. Notably, K@RWY also demonstrates a strong tolerance toward water.

  15. Renaissance of Cation-Radicals in Mass Spectrometry

    OpenAIRE

    Tureček, František

    2013-01-01

    This brief overview addresses the topic that was presented in the Thomson Medal Award session at the 19th International Mass Spectrometry Conference in Kyoto, Japan. Mass spectrometry of cation-radicals has enjoyed a remarkable renaissance thanks to the development of new methods for electron attachment to multiply charged peptide ions. The charge-reduced ions that are odd-electron species exhibit interesting reactivity that is useful for peptide and protein sequencing. The paper briefly revi...

  16. Nitrogen heteroaromatic cations by [2+2+2] cycloaddition

    Czech Academy of Sciences Publication Activity Database

    Čížková, Martina; Kolivoška, Viliam; Císařová, I.; Šaman, David; Pospíšil, Lubomír; Teplý, Filip

    2011-01-01

    Roč. 9, č. 2 (2011), s. 450-462 ISSN 1477-0520 R&D Projects: GA ČR GA203/09/1614; GA ČR GA203/09/0705; GA MŠk OC 140 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40400503 Keywords : modular synthesis * N-heteroaromatic cation * [2+2+2] cycloaddition Subject RIV: CC - Organic Chemistry Impact factor: 3.696, year: 2011

  17. The complex nature of calcium cation interactions with phospholipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Melcrová, Adéla; Pokorná, Šárka; Pullanchery, S.; Kohagen, Miriam; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cremer, P. S.; Cwiklik, Lukasz

    2016-01-01

    Roč. 6, DEC 2016 (2016), č. článku 38035. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GA16-01074S Institutional support: RVO:61388955 ; RVO:61388963 Keywords : FLUORESCENCE SOLVENT RELAXATION * MOLECULAR-DYNAMICS SIMULATIONS * ALKALINE-EARTH CATIONS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.259, year: 2016

  18. Temporal Deductive Verification of Basic ASM Models

    OpenAIRE

    Daho, Hocine El-Habib; University of Oran; Benhamamouch, Djillali; University of Oran

    2010-01-01

    Abstract State Machines (ASMs, for short) provide a practical new computational model which has been applied in the area of software engineering for systems design and analysis. However, reasoning about ASM models occurs, not within a formal deductive system, but basically in the classical informal proofs style of mathematics. Several formal verification approaches for proving correctness of ASM models have been investigated. In this paper we consider the use of the TLA+logic for the deductive...

  19. Effect of hydroxide polymenrs on cation exchange of montmorillonite

    NARCIS (Netherlands)

    Janssen, R.P.T.; Bruggenwert, M.G.M.; Riemsdijk, van W.H.

    2003-01-01

    Al hydroxide polymers (AlHO) can significantly influence the cation exchange behaviour of clays. We have determined the effect of synthesized AlHO on Ca¿Na, Zn¿Na and Pb¿Na exchange for a series of exchanger compositions and two Al loadings at pH 6.0 and an ionic strength of 0.01 m. The preference

  20. Insertion of cations into WO3 investigated by QCM techniques

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Jiří; Sedlaříková, M.; Velická, Jana; Špičák, P.; Svoboda, V.; Kazelle, J.

    2007-01-01

    Roč. 11, č. 10 (2007), s. 1459-1462 ISSN 1432-8488 R&D Projects: GA MŽP SN/3/171/05; GA AV ČR(CZ) KJB208130604; GA ČR(CZ) GA104/06/1471 Institutional research plan: CEZ:AV0Z40320502 Keywords : tungsten trioxide * insertion of cations * quartz crystal microbalance Subject RIV: CG - Electrochemistry Impact factor: 1.535, year: 2007

  1. A Review on Adsorption of Cationic Dyes using Activated Carbon

    Directory of Open Access Journals (Sweden)

    Corda Nikita Chrishel

    2018-01-01

    Full Text Available In this article efficiency of activated carbon as a potent adsorbent of cationic dyes has been reviewed. Non-biodegradable nature of pollutants and their removal in the present generation is a great challenge. Therefore, extensive study on adsorption of these classes of pollutants from water bodies is being carried out. Methylene blue (majorly a dye seen in the effluent streams of textile, printing, paper industries along with some of the commonly used cationic dyes in process industries and their sorption on activated carbon are reviewed here. High cost of commercially activated carbon which is a limitation to its extensive use have paved way for study of adsorption by naturally obtained and extracted activated carbon from agricultural wastes and various other sources. The purpose of this review paper is to summarize the available information on the removal of cationic dyes using naturally extracted and commercially obtained activated carbon. Various parameters such as temperature, initial dye concentration, pH, contact time, adsorbent dosage, particle size, stirring, agitation etc. were studied and the optimum parameters were determined based on the experimental outcomes. Equilibrium data was examined using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich and few other isotherm models. Kinetic studies also have been carried out to find the most suitable way of expressing the adsorption process.

  2. The mechanochemical production of phenyl cations through heterolytic bond scission.

    Science.gov (United States)

    Shiraki, Tomohiro; Diesendruck, Charles E; Moore, Jeffrey S

    2014-01-01

    High mechanical forces applied to polymeric materials typically induce unselective chain scission. For the last decade, mechanoresponsive molecules, mechanophores, have been designed to harness the mechanical energy applied to polymers and provide a productive chemical response. The selective homolysis of chemical bonds was achieved by incorporating peroxide and azo mechanophores into polymer backbones. However, selective heterolysis in polymer mechanochemistry is still mostly unachieved. We hypothesized that highly polarized bonds in ionic species are likely to undergo heterolytic bond scission. To test this, we examined a triarylsulfonium salt (TAS) as a mechanophore. Poly(methyl acrylate) possessing TAS at the center of the chain (PMA-TAS) is synthesized by a single electron transfer living radical polymerization (SET-LRP) method. Computational and experimental studies in solution reveal the mechanochemical production of phenyl cations from PMA-TAS. Interestingly, the generated phenyl cation reacts with its counter-anion (trifluoromethanesulfonate) to produce a terminal trifluoromethyl benzene structure that, to the best of our knowledge, is not observed in the photolysis of TAS. Moreover, the phenyl cation can be trapped by the addition of a nucleophile. These findings emphasize the interesting reaction pathways that become available by mechanical activation.

  3. Metal cation uptake and reduction kinetics in microalgal cell culture

    Science.gov (United States)

    Kare, Anudeep

    This work was conducted to create a bio synthetic process for production of sustainable Nano materials, such as Noble metal nanoparticles with the use of living organisms as catalysts. Dactylococcus, Coelastrella and Chlamydomonas reinhardtii are the different species of algae used through which the Au and Ag nanoparticles are extracted. Under the appropriate bioprocess conditions phototrophic algal cell cultures can catalyze the conversion of soluble metal cations, such as trivalent gold cation (Au+3), to metallic gold nanoparticles (Au0 NP) and silver cation (Ag+) to metallic silver nanoparticles (Ag0 NP). The primary objective of this experiment is to identify the rate-limiting kinetics such as, mixing, biological, pH and so forth to see whether a scalable process can be proposed for production of these high valued materials. It is proposed in the literature that the reducing power required to drive this reaction is derived from the electron flux produced in the algae's photosynthetic apparatus. However, due to the lack of fundamental knowledge about the transport and kinetics, and therefore the bottlenecks and key process parameters, there is currently no scalable, controllable phototrophic system has been developed for the production of metallic nanoparticles.

  4. Electronically Unsaturated Three-Coordinate Aluminum Hydride and Organoaluminum Cations.

    Science.gov (United States)

    Prashanth, Billa; Bhandari, Mamta; Ravi, Satyam; Shamasundar, K R; Singh, Sanjay

    2018-02-16

    New three-coordinate and electronically unsaturated aluminum hydride [LAlH] + [HB(C 6 F 5 ) 3 ] - (LH=[{(2,6-iPr 2 C 6 H 3 N)P(Ph 2 )} 2 N]H) and aluminum methyl [LAlMe] + [MeB(C 6 F 5 ) 3 ] - cations have been prepared. The quantitative estimation of Lewis acidity by Gutmann-Beckett method revealed [LAlH] + [HB(C 6 F 5 ) 3 ] - to be better Lewis acid than B(C 6 F 5 ) 3 and AlCl 3 making these compounds ideal catalysts for Lewis acid-mediated reactions. To highlight that the work is of fundamental importance, catalytic hydroboration of aliphatic and aromatic aldehydes and ketones have been demonstrated. Important steps of the catalytic cycle have been probed by using multinuclear NMR measurements, including successful characterization of the proposed aluminum benzyloxide cationic intermediate, [LAl-O-CH 2 Ph] + [HB(C 6 F 5 ) 3 ] - . The proposed catalytic cycle has been found to be consistent with experimental observations and computational studies clearly indicating the migration of hydride from cationic aluminum center to the carbonyl carbon is the rate-limiting step of the catalytic cycle. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The chemistry of separations ligand degradation by organic radical cations

    International Nuclear Information System (INIS)

    Mezyk, S.P.; Horne, G.P.; Mincher, B.J.; Zalupski, P.R.; Cook, A.R.; Wishart, J.F.

    2016-01-01

    Solvent based extractions of used nuclear fuel use designer ligands in an organic phase extracting ligand complexed metal ions from an acidic aqueous phase. These extractions will be performed in highly radioactive environments, and the radiation chemistry of all these complexing agents and their diluents will play a major role in determining extraction efficiency, separation factors, and solvent-recycle longevity. Although there has been considerable effort in investigating ligand damage occurring in acidic water radiolysis conditions, only minimal fundamental kinetic and mechanistic data has been reported for the degradation of extraction ligands in the organic phase. Extraction solvent phases typically use normal alkanes such as dodecane, TPH, and kerosene as diluents. The radiolysis of such diluents produce a mixture of radical cations (R .+ ), carbon-centered radicals (R . ), solvated electrons, and molecular products such as hydrogen. Typically, the radical species will preferentially react with the dissolved oxygen present to produce relatively inert peroxyl radicals. This isolates the alkane radical cation species, R .+ as the major radiolytically-induced organic species that can react with, and degrade, extraction agents in this phase. Here we report on our recent studies of organic radical cation reactions with 2 ligands: CMPO and TODGA. Elucidating these parameters, and combining them with the known acidic aqueous phase chemistry, will allow a full, fundamental, understanding of the impact of radiation on solvent extraction based separation processes to be achieved. (authors)

  6. Modulation of Group I Ribozyme Activity by Cationic Porphyrins

    Directory of Open Access Journals (Sweden)

    Shigeyoshi Matsumura

    2015-03-01

    Full Text Available The effects of cationic porphyrins on the catalytic activities of four group I ribozymes were investigated. A cationic porphyrin possessing four pyridinium moieties (pPyP inhibited two group IC3 ribozymes (Syn Rz and Azo Rz and a group IC1 ribozyme (Tet Rz. In the case of a group IA2 ribozyme (Td Rz, however, pPyP served not only as an inhibitor but also as an activator, and the effects of pPyP were dependent on its concentration. To analyze the structural and electronic factors determining the effects of pPyP on group I ribozymes, three cationic porphyrins (pPyNCP, pPyF4P, and TMPyP were also examined. As interactions between small organic molecules and nucleic acids are attractive and important issues in biochemistry and biotechnology, this study contributes to the development of porphyrin-based molecules that can modulate functions of structured RNA molecules.

  7. Drug loading to lipid-based cationic nanoparticles

    International Nuclear Information System (INIS)

    Cavalcanti, Leide P.; Konovalov, Oleg; Torriani, Iris L.; Haas, Heinrich

    2005-01-01

    Lipid-based cationic nanoparticles are a new promising option for tumor therapy, because they display enhanced binding and uptake at the neo-angiogenic endothelial cells, which a tumor needs for its nutrition and growth. By loading suitable cytotoxic compounds to the cationic carrier, the tumor endothelial and consequently also the tumor itself can be destroyed. For the development of such novel anti-tumor agents, the control of drug loading and drug release from the carrier matrix is essential. We have studied the incorporation of the hydrophobic anti-cancer agent Paclitaxel (PXL) into a variety of lipid matrices by X-Ray reflectivity measurements. Liposome suspensions from cationic and zwitterionic lipids, comprising different molar fractions of Paclitaxel, were deposited on planar glass substrates. After drying at controlled humidity, well ordered, oriented multilayer stacks were obtained, as proven by the presence of bilayer Bragg peaks to several orders in the reflectivity curves. The presence of the drug induced a decrease of the lipid bilayer spacing, and with an excess of drug, also Bragg peaks of drug crystals could be observed. From the results, insight into the solubility of Paclitaxel in the model membranes was obtained and a structural model of the organization of the drug in the membrane was derived. Results from subsequent pressure/area-isotherm and grazing incidence diffraction (GID) measurements performed with drug/lipid Langmuir monolayers were in accordance with these conjectures

  8. Sorption and fixation of large cations by shale formations

    International Nuclear Information System (INIS)

    Brindley, G.W.

    1977-01-01

    Large cations such as Cs + are preferentially sorbed and partially fixed by fine-grained 2 : 1 type layer silicates such as micas, vermiculites, smectites and various mixed-layer minerals. Since these minerals are common constituents of many shale formations, these formations may provide suitable location for the burial of radioactive waste containers. However, the usual investigations of cation sorption and fixation must be extended to the conditions likely to develop in the vicinity of buried radioactive waste. Prior to possible leakage from buried containers, elevated temperatures around the burial site will develop leading to hydrothermal modification of the surrounding mineralogy. A range of temperature and of mineralogy must be envisaged. If and when leakage occurs, an outward diffusion of radioactive ions will occur by solvation in the fluids in the shale. The ratio of radioactive ions/normal ions will diminish outwards from the source. At near distances from the source high temperature modifications of the clay minerals and high concentrations of radioactive cations may lead to saturation of the fixation capacity. At greater distances, little or no thermal modification of the clay minerals and lower concentrations of ions will permit maximum sorption and fixation

  9. TRPP2 and TRPV4 form an EGF-activated calcium permeable channel at the apical membrane of renal collecting duct cells.

    Directory of Open Access Journals (Sweden)

    Zhi-Ren Zhang

    Full Text Available Regulation of apical calcium entry is important for the function of principal cells of the collecting duct. However, the molecular identity and the regulators of the transporter/channel, which is responsible for apical calcium entry and what factors regulate the calcium conduction remain unclear.We report that endogenous TRPP2 and TRPV4 assemble to form a 23-pS divalent cation-permeable non-selective ion channel at the apical membrane of renal principal cells of the collecting duct. TRPP2\\TRPV4 channel complex was identified by patch-clamp, immunofluorescence and co-immunprecipitation studies in both principal cells that either possess normal cilia (cilia (+ or in which cilia are absent (cilia (-. This channel has distinct biophysical and pharmacological and regulatory profiles compared to either TRPP2 or TRPV4 channels. The rate of occurrence detected by patch clamp was higher in cilia (- compared to cilia (+ cells. In addition, shRNA knockdown of TRPP2 increased the prevalence of TRPV4 channel activity while knockdown of TRPV4 resulted in TRPP2 activity and knockdown of both proteins vastly decreased the 23-pS channel activity. Epidermal growth factor (EGF stimulated TRPP2\\TRPV4 channel through the EGF receptor (EGFR tyrosine kinase-dependent signaling. With loss of cilia, apical EGF treatment resulted in 64-fold increase in channel activity in cilia (- but not cilia (+ cells. In addition EGF increased cell proliferation in cilia (- cell that was dependent upon TRPP2\\TRPV4 channel mediated increase in intracellular calcium.We conclude that in the absence of cilia, an EGF activated TRPP2\\TRPV4 channel may play an important role in increased cell proliferation and cystogenesis.

  10. Language Non-Selective Activation of Orthography during Spoken Word Processing in Hindi-English Sequential Bilinguals: An Eye Tracking Visual World Study

    Science.gov (United States)

    Mishra, Ramesh Kumar; Singh, Niharika

    2014-01-01

    Previous psycholinguistic studies have shown that bilinguals activate lexical items of both the languages during auditory and visual word processing. In this study we examined if Hindi-English bilinguals activate the orthographic forms of phonological neighbors of translation equivalents of the non target language while listening to words either…

  11. Ultrasonic dyeing of cationized cotton fabric with natural dye. Part 1: cationization of cotton using Solfix E.

    Science.gov (United States)

    Kamel, M M; El Zawahry, M M; Ahmed, N S E; Abdelghaffar, F

    2009-02-01

    The dyeing of cationized cotton fabric with Solfix E using colouring matter extracted from Cochineal dye has been studied using both conventional and ultrasonic techniques. Factors affecting dye extraction such as ultrasound power, particle size, extraction temperature and time were studied. The results indicated that the extraction by ultrasound at 300 W was more effective at lower temperature and time than conventional extraction. The effect of various factors of dye bath such as pH, salt concentration, ultrasound power, dyeing time and temperature were investigated. The colour strength values obtained were found to be higher with ultrasound than with conventional techniques. The results of fastness properties of the dyed fabrics were fair to good. The scanning electron microscope (SEM) images of the morphological and X-ray analyzes were measured for cationized cotton fabrics dyed with both conventional and ultrasound methods, thus showing the sonicator efficiency.

  12. A partially substituted calix[4]resorcarene receptor and its selective recognition for soft metal cations (silver and mercury).

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K

    2008-02-21

    A partially substituted calix[4]resorcarene receptor, namely, 5,17-ethylthiomethylated calix[4]resorcarene, 1, has been synthesized and characterized by 1H NMR in CD3OD, CDCl3, and CD3CN and 13C NMR in CD3OD, as well as by 2D NMR. Partition data in the methanol-hexane and acetonitrile-hexane solvent systems show that the monomeric species are predominant in these solvents. The solubility of 1 in various solvents was determined at 298.15 K. These data were used to calculate the standard solution Gibbs energy of 1 in these solvents. Taking hexane as the reference solvent, the standard transfer Gibbs energy of 1 to various solvents was calculated. Good agreement is found between the DeltatG(o) values in the hexane-methanol and hexane-acetonitrile and the DeltapG(o) values of this ligand in these solvent systems. The higher partition constant of 1 in the hexane-methanol relative to the hexane-acetonitrile solvent system contrasts with corresponding data for the fully functionalized receptor, 2. This is explained in terms of the solvation differences of these receptors in these solvents as reflected in the DeltatG(o) values. The cation complexing properties of this receptor were investigated through 1H NMR, conductance, calorimetric, and potentiometric methods. Among the metal cations (alkali, alkaline earth, heavy, and transition), 1 interacts only with Ag+ in methanol and Hg2+ in propylene carbonate, acetonitrile, methanol, and N,N-dimethylformamide. While 1 forms a 1:1 complex with Ag+ in methanol, the hosting ability of the receptor for the mercury cation is enhanced in methanol, acetonitrile, and N,N-diethylformamide. Thus, Hg2+ complexes of 1:2 (ligand:metal cation) stoichiometry are found in these solvents. In moving to propylene carbonate, the composition of the mercury complex is altered from 1:2 to 1:1. The results are compared with corresponding data for 2 and these metal cations in the appropriate solvents. The lack of stability observed for 2 and Hg2+ in

  13. The combination between cations and sulfated polysaccharide from abalone gonad (Haliotis discus hannai Ino).

    Science.gov (United States)

    Guo, Yiming; Cong, Shuang; Zhao, Jun; Dong, Yingying; Li, Tingting; Zhu, Beiwei; Song, Shuang; Wen, Chengrong

    2018-05-15

    Effects of cations (Na + , K + , Ca 2+ , Mg 2+ ) on the structure of abalone gonad sulfated polysaccharide (AGSP) were studied by means of Congo red test, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the local ordered helical conformation was observed in AGSP. The cations could combine with anionic groups in AGSP by ionic bonds, which caused the weakening of electrostatic repulsion and crosslinking of molecular chains. Furthermore, the effects of divalent cations on the conformation were more obvious than that of monovalent cations, and divalent cations led to the aggregation of AGSP due to the more interaction sites. In short, AGSP molecular chains were crosslinked through ionic bonds after adding cations, and, divalent cations could induce the aggregation of AGSP by electrostatic interactions. This study will provide valuable insights for the further research on AGSP conformation. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Simultaneous precipitation of carbonato complexes of uranium and plutonium with cationic surfactants

    International Nuclear Information System (INIS)

    Heckmann, K.; Strnad, J.; Huber, K.

    1992-01-01

    The proposed method allows to separate Uranium, Thorium and Cerium from carbonate solutions and the further processing of these metals to mixed oxides. The separation can be divided into three steps: 1. Precipitation of the metals with a 10-fold surplus of carbonate and a 5-fold surplus of a cationic surfactant. 2. Thermal decomposition of the precipitates in air at 600 C. 3. Reduction of U(VI) to U(IV) with CO at 500 C. Mixed oxides in any ratio are formed in this way. This is possible due to the coprecipitation of both metals. Comparing the standard potentials it is clear that Ce(IV) is more easily reduced that Pu(IV). Therefore, the chance on the formation of U/Pu mixed oxides by this method is quite good. (orig.) [de

  15. Extraction of metal cations by polyterephthalamide microcapsules containing a poly(acrylic acid) gel.

    Science.gov (United States)

    Laguecir, A; Ernst, B; Frère, Y; Danicher, L; Burgard, M

    2002-01-01

    Polyterephthalamide microcapsules containing a poly(acrylic acid) gel as a macromolecular ligand (PAA-CAPS) were prepared using an original two step polymerization process in a water-in-oil inverse emulsion system. A polyamide microcapsule containing acrylic acid, initiator and cross-linking agent, is formed by interfacial polycondensation of terephthaloyl dichloride with hexamethylenediamine. In situ radical polymerization of the microcapsule core acrylic acid is initiated to obtain encapsulated poly(acrylic acid) gel. Reference polyamide microcapsules, i.e. without ligand (CAPS), were also synthesized. The mean diameter of synthesized microcapsules was 210 microm, and the microcapsule wall thickness was evaluated by SEM and TEM observations of microcapsule cross-section cuts. The microcapsule water content was determined by thermogravimetric experiments. The extractabilities of Cu(II), Ni(II), Co(II) and Zn(II) into PAA-CAPS were examined. The stripping of the various cations can be promoted in diluted hydrochloric acid solutions.

  16. Development of Comparative Toxicity Potentials of 14 cationic metals in freshwater

    DEFF Research Database (Denmark)

    Dong, Yan; Gandhi, Nilima; Hauschild, Michael Zwicky

    2014-01-01

    . CTPs were calculated for 7 EUarchetypes, taking bioavailability and speciation pattern into account. The resulting site-dependent CTPs showed up to 2.4–6.5 orders of magnitude variation across archetypes for those metals that form stable hydroxyl compounds in slightly alkaline waters (Al(III), Be, Cr......Site-dependent and site-generic Comparative Toxicity Potentials (CTPs) (also known as Characterization Factors (CFs)) were calculated for 14 cationic metals (Al(III), Ba, Be, Cd, Co, Cr(III), Cs, Cu(II), Fe(II), Fe(III), Mn(II), Ni, Pb, Sr and Zn), to be applied in Life Cycle Impact Assessment......(III), Cu(II) and Fe(III)), emphasizing the importance of using site-dependent CTPs for these metals where possible. For the other metals, CTPs stayed within around 0.9 orders of magnitude, making spatial differentiation less important. In acidic waters (pH

  17. Impedance Spectroscopy Study of the Electrical Properties of Cation-Substituted Barium Hexaaluminate Ceramics

    Science.gov (United States)

    Belyaev, B. A.; Drokin, N. A.; Poluboyarov, V. A.

    2018-02-01

    We report on the behavior of frequency and temperature dependences of the impedance of a measuring cell in the form of a parallel-plate capacitor filled with barium hexaaluminate ceramics with four aluminum cations replaced by iron (BaO · 2Fe2O3 · 4Al2O3). The measurements have been performed in the frequency range of 0.5-108 Hz at temperatures of 20-375°C. A technique for determining the electrical properties of the investigated ceramics is proposed, which is based on an equivalent electric circuit allowing the recorded impedance spectra to be approximated with sufficiently high accuracy. The established spectral features are indicative of the presence of two electric relaxation times different from each other by three orders of magnitude. This fact is explained by the difference between the charge transport processes in the bulk of crystallites and thin intercrystallite spacers, for which the charge activation energies have been determined.

  18. Atomistic studies of cation transport in tetragonal ZrO2 during zirconium corrosion

    International Nuclear Information System (INIS)

    Bai, Xian-Ming; Zhang, Yongfeng; Tonks, Michael R.

    2015-01-01

    Zirconium alloys are the major fuel cladding materials in current reactors. The water-side corrosion is a significant degradation mechanism of these alloys. During corrosion, the transport of oxidizing species in zirconium dioxide (ZrO 2 ) determines the corrosion kinetics. Previously, it has been argued that the outward diffusion of cations is important for forming protective oxides. In this work, the migration of Zr defects in tetragonal ZrO 2 is studied with temperature accelerated dynamics and molecular dynamics simulations. The results show that Zr interstitials have anisotropic diffusion and migrate preferentially along the [001] or c direction in tetragonal ZrO 2 . The compressive stresses can increase the Zr interstitial migration barrier significantly. The migration of Zr interstitials at a grain boundary is much slower than in a bulk oxide. The implications of these atomistic simulation results in the Zr corrosion are discussed. (authors)

  19. Inhibition of trypanosome alternative oxidase without its N-terminal mitochondrial targeting signal (ΔMTS-TAO) by cationic and non-cationic 4-hydroxybenzoate and 4-alkoxybenzaldehyde derivatives active against T. brucei and T. congolense.

    Science.gov (United States)

    Ebiloma, Godwin U; Ayuga, Teresa Díaz; Balogun, Emmanuel O; Gil, Lucía Abad; Donachie, Anne; Kaiser, Marcel; Herraiz, Tomás; Inaoka, Daniel K; Shiba, Tomoo; Harada, Shigeharu; Kita, Kiyoshi; de Koning, Harry P; Dardonville, Christophe

    2018-04-25

    African trypanosomiasis is a neglected parasitic disease that is still of great public health relevance, and a severe impediment to agriculture in endemic areas. The pathogens possess certain unique metabolic features that can be exploited for the development of new drugs. Notably, they rely on an essential, mitochondrially-localized enzyme, Trypanosome Alternative Oxidase (TAO) for their energy metabolism, which is absent in the mammalian hosts and therefore an attractive target for the design of safe drugs. In this study, we cloned, expressed and purified the physiologically relevant form of TAO, which lacks the N-terminal 25 amino acid mitochondrial targeting sequence (ΔMTS-TAO). A new class of 32 cationic and non-cationic 4-hydroxybenzoate and 4-alkoxybenzaldehyde inhibitors was designed and synthesized, enabling the first structure-activity relationship studies on ΔMTS-TAO. Remarkably, we obtained compounds with enzyme inhibition values (IC 50 ) as low as 2 nM, which were efficacious against wild type and multidrug-resistant strains of T. brucei and T. congolense. The inhibitors 13, 15, 16, 19, and 30, designed with a mitochondrion-targeting lipophilic cation tail, displayed trypanocidal potencies comparable to the reference drugs pentamidine and diminazene, and showed no cross-resistance with the critical diamidine and melaminophenyl arsenical classes of trypanocides. The cationic inhibitors 15, 16, 19, 20, and 30 were also much more selective (900 - 344,000) over human cells than the non-targeted neutral derivatives (selectivity >8-fold). A preliminary in vivo study showed that modest doses of 15 and 16 reduced parasitaemia of mice infected with T. b. rhodesiense (STIB900). These compounds represent a promising new class of potent and selective hits against African trypanosomes. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  20. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations.

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E

    2006-02-09

    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  1. Directionality of Cation/Molecule Bonding in Lewis Bases Containing the Carbonyl Group.

    Science.gov (United States)

    Valadbeigi, Younes; Gal, Jean-François

    2017-09-14

    Relationship between the C═O-X + (X = H, Li, Na, K, Al, Cu) angle and covalent characteristic of the X + -M (M = CH 2 O, CH 3 CHO, acetone, imidazol-2-one (C 2 H 2 N 2 O), cytosine, γ-butyrolactone) was investigated, theoretically. The calculated electron densities ρ at the bond critical points revealed that the covalency of the M-X + interaction depended on the nature of the cation and varied as H + > Cu + > Al + > Li + > Na + > K + . The alkali cations tended to participate in electrostatic interactions and aligned with the direction of the molecule dipole or local dipole of C═O group to form linear C═O-X geometries. Because of overlapping with lone-pair electrons of the sp 2 carbonyl oxygen, the H + and Cu + formed a bent C═O-X angle. Al + displayed an intermediate behavior; the C═O-Al angle was 180° in [CH 2 O/Al] + (mainly electrostatic), but when the angle was bent (146°) under the effect of local dipole of an adjacent imine group in cytosine, the covalency of the CO-Al + interaction increased. The C═O-X angles in M/X + adduct ions were scanned in different O-X bond lengths. It was found that the most favorable C═O-X angle depended on the O-X bond length. This dependency was attributed to variation of covalent and electrostatic contributions with O-X distance. In addition, the structures of [CH 2 S/X] + and [CH 2 Se/X] + were studied, and only bent C═S-X and C═Se-X angles were obtained for all cations, although the dipole vectors of CH 2 S and CH 2 Se coincide with the C═S and C═Se bonds. The bending of the C═S-X and C═Se-X angles was attributed to the covalent characteristic of S-X and Se-X interactions due to high polarizability of S and Se atoms.

  2. Effect of Relative Arrangement of Cationic and Lipophilic Moieties on Hemolytic and Antibacterial Activities of PEGylated Polyacrylates

    Directory of Open Access Journals (Sweden)

    Ashish Punia

    2015-10-01

    Full Text Available Synthetic amphiphilic polymers have been established as potentially efficient agents to combat widespread deadly infections involving antibiotic resistant superbugs. Incorporation of poly(ethylene glycol (PEG side chains into amphiphilic copolymers can reduce their hemolytic activity while maintaining high antibacterial activity. Our study found that the incorporation of PEG has substantially different effects on the hemolytic and antibacterial activities of copolymers depending on structural variations in the positions of cationic centers relative to hydrophobic groups. The PEG side chains dramatically reduced the hemolytic activities in copolymers with hydrophobic hexyl and cationic groups on the same repeating unit. However, in case of terpolymers with cationic and lipophilic groups placed on separate repeating units, the presence of PEG has significantly lower effect on hemolytic activities of these copolymers. PEGylated terpolymers displayed substantially lower activity against Staphylococcus aureus (S. aureus than Escherichia coli (E. coli suggesting the deterring effect of S. aureus’ peptidoglycan cell wall against the penetration of PEGylated polymers. Time-kill studies confirmed the bactericidal activity of these copolymers and a 5 log reduction in E. coli colony forming units was observed within 2 h of polymer treatment.

  3. Facile Arylation of Four-Coordinate Boron Halides by Borenium Cation Mediated Boro-desilylation and -destannylation.

    Science.gov (United States)

    Crossley, Daniel L; Cid, Jessica; Curless, Liam D; Turner, Michael L; Ingleson, Michael J

    2015-12-28

    The addition of AlCl 3 to four-coordinate boranes of the general formula (C-N-chelate)BCl 2 results in halide abstraction and formation of three-coordinate borenium cations of the general formula [(C-N-chelate)BCl] + . The latter react with both arylstannanes and arylsilanes by boro-destannylation and -desilylation, respectively, to form arylated boranes. Catalytic quantities of AlCl 3 were sufficient to effect high-yielding arylation of (C-N-chelate)BCl 2 . Boro-destannylation is more rapid than boro-desilylation and leads to double arylation at the boron center, whereas in reactions with arylsilanes either single or double arylation occurs dependent on the nucleophilicity of the arylsilane and on the electrophilicity of the borenium cation. The electrophilicity of the borenium cation derived from 2-phenylpyridine was greater than that of the benzothiadiazole analogues, enabling the boro-desilyation of less nucleophilic silanes and the direct electrophilic borylation of 2-methylthiophene.

  4. Protective efficacy of cationic-PLGA microspheres loaded with DNA vaccine encoding the sip gene of Streptococcus agalactiae in tilapia.

    Science.gov (United States)

    Ma, Yan-Ping; Ke, Hao; Liang, Zhi-Ling; Ma, Jiang-Yao; Hao, Le; Liu, Zhen-Xing

    2017-07-01

    Streptococcus agalactiae (S. agalactiae) is an important fish pathogen, which has received more attention in the past decade due to the increasing economic losses in the tilapia industry worldwide. As existing effective vaccines of S. agalactiae in fish have obvious disadvantage, to select immunoprotective antigens and package materials would undoubtedly contribute to the development of novel oral vaccines. In the present study, surface immunogenic protein (sip) was selected from the S. agalactiae serovar I a genomes as immunogenic protein in DNA vaccine form with cationic chitosan and biodegradable and biocompatible PLGA. The pcSip plasmid in cationic-PLGA was successfully expressed in tissues of immunized tilapia and the immunogenicity was assessed in tilapia challenge model. A significant increase was observed in the cytokine levels of IL-1β, TNF-α, CC1, CC2 in spleen and kidney tissues. Furthermore, immunized tilapia conferred different levels of protection against challenge with a lethal dose of highly virulent serovar I a S. agalactiae. Our results indicated that the pcSip plasmid in cationic-PLGA induced high level of antibodies and protection against S. agalactiae infection, could be effective oral DNA vaccine candidates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. A colorimetric aptamer biosensor based on cationic polythiophene derivative as peroxidase mimetics for the ultrasensitive detection of thrombin.

    Science.gov (United States)

    Liu, Mei; Li, Jiao; Li, Baoxin

    2017-12-01

    A colorimetric assay for the ultrasensitive determination of thrombin was presented, in which the cationic polythiophene derivative was used as catalyst of the 3,3',5,5'-tetramethylbenzidine (TMB)-H 2 O 2 reaction and the thrombin-binding aptamer (TBA) was used as inducing polymer's different conformation elements. It was found the cationic polythiophene derivative, poly[3-(3'-N,N,N-triethylamino-1'-propyloxy)-4-methyl-2,5-t-hiophene hydrochloride] (PMNT), can catalyze the oxidation reaction of TMB in the presence of H 2 O 2 to produce a blue color solution. The catalytic activity of PMNT on the TMB-H 2 O 2 reaction was closely relevant to the conformation of PMNT. The absorbance of TMB-H 2 O 2 was distinctly increased in the presence of TBA. With the addition of thrombin, TBA interacted with thrombin to form a G-quadruplex structure. The conformational change weakened the catalytic activity of PMNT and resulted in a decrease in the absorbance. The colorimetric sensor could detect thrombin down to 4pM with high selectivity against other interfering proteins. This work is not only of importance for a better understanding of the unique properties of cationic polythiophenes derivative but also have great potential for medical diagnostics and therapy for human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Design, synthesis, and evaluation of gadolinium cationic lipids as tools for biodistribution studies of gene delivery complexes.

    Science.gov (United States)

    Leclercq, Francoise; Cohen-Ohana, Mirit; Mignet, Nathalie; Sbarbati, Andrea; Herscovici, Jean; Scherman, Daniel; Byk, Gerardo

    2003-01-01

    Gadolinium-chelating cationic lipids have been synthesized to obtain lipoplexes with MRI contrast properties. These compounds were designed to follow the biodistribution of synthetic DNA for gene delivery by nuclear magnetic resonance imaging. The lipid MCO-I-68 was synthesized, and chelate complexes with gadolinium were formed and characterized in terms of physicochemical and DNA binding properties. The transfection activity of MCO-I-68-Gd/DNA complexes was assayed in vitro on NIH 3T3. Different formulations of the product were tested. When up to 5% of the gadolinium lipid complexes were co-formulated with the cationic lipid RPR120535 used as a reference, the transfection levels were maintained as compared to RPR120535 alone. To date, only a liposomal formulation of a gadolinium-cationic lipid chelate without DNA had been observed using magnetic resonance imaging. In vivo intratumoral administration of MCO-I-68-Gd/DNA lipoplexes to tumor model led to an important increase of the NMR signal. It was demonstrated that the new complexes also acted as transfection carriers when they were formulated from liposomes.

  7. Halohydrination of epoxy resins using sodium halides as cationizing agents in MALDI-MS and DIOS-MS.

    Science.gov (United States)

    Watanabe, Takehiro; Kawasaki, Hideya; Kimoto, Takashi; Arakawa, Ryuichi

    2008-12-01

    Halohydrination of epoxy resins using sodium halides as cationizing agents in matrix-assisted laser desorption/ionization (MALDI) and desorption ionization on porous silicon mass spectrometry (DIOS-MS) were investigated. Different mass spectra were observed when NaClO(4) and NaI were used as the cationizing agents at the highest concentration of 10.0 mM, which is much higher than that normally used in MALDI-MS. MALDI mass spectra of epoxy resins using NaI revealed iodohydrination to occur as epoxy functions of the polymers. The halohydrination also occurred using NaBr, but not NaCl, due to the differences in their nucleophilicities. On the basis of the results of experiments using deuterated CD(3)OD as the solvent, the hydrogen atom source was probably ambient water or residual solvent, rather than being derived from matrices. Halohydrination also occurred with DIOS-MS in which no organic matrix was used; in addition, reduction of epoxy functions was observed with DIOS. NaI is a useful cationizing agent for changing the chemical form of epoxy resins due to iodohydrination and, thus, for identifying the presence of epoxy functions. Copyright (c) 2008 John Wiley & Sons, Ltd.

  8. Cation-pi interaction of the univalent silver cation with racemic [6]helicene in the gas phase and in the solid state

    Czech Academy of Sciences Publication Activity Database

    Klepetářová, Blanka; Makrlík, E.; Sýkora, D.; Böhm, S.; Vaňura, P.

    2016-01-01

    Roč. 117, Oct 15 (2016), s. 1-6 ISSN 0277-5387 Institutional support: RVO:61388963 Keywords : univalent silver cation * [6]helicene * cation-pi interaction * DFT calculations * X-ray crystallography Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.926, year: 2016

  9. Harmonic Maass forms and mock modular forms

    CERN Document Server

    Bringmann, Kathrin; Ono, Ken

    2017-01-01

    Modular forms and Jacobi forms play a central role in many areas of mathematics. Over the last 10-15 years, this theory has been extended to certain non-holomorphic functions, the so-called "harmonic Maass forms". The first glimpses of this theory appeared in Ramanujan's enigmatic last letter to G. H. Hardy written from his deathbed. Ramanujan discovered functions he called "mock theta functions" which over eighty years later were recognized as pieces of harmonic Maass forms. This book contains the essential features of the theory of harmonic Maass forms and mock modular forms, together with a wide variety of applications to algebraic number theory, combinatorics, elliptic curves, mathematical physics, quantum modular forms, and representation theory.

  10. Harmonic maass forms and mock modular forms

    CERN Document Server

    Bringmann, Kathrin; Ono, Ken

    2017-01-01

    Modular forms and Jacobi forms play a central role in many areas of mathematics. Over the last 10-15 years, this theory has been extended to certain non-holomorphic functions, the so-called "harmonic Maass forms". The first glimpses of this theory appeared in Ramanujan's enigmatic last letter to G. H. Hardy written from his deathbed. Ramanujan discovered functions he called "mock theta functions" which over eighty years later were recognized as pieces of harmonic Maass forms. This book contains the essential features of the theory of harmonic Maass forms and mock modular forms, together with a wide variety of applications to algebraic number theory, combinatorics, elliptic curves, mathematical physics, quantum modular forms, and representation theory.

  11. Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Makowski, Mariusz [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)], E-mail: lech@chem.univ.gda.pl

    2007-09-15

    Hydrogen bond OHO-type bridges formed between six substituted 4-halo (Cl, Br) pyridine N-oxide systems and their simple cations have been investigated by using the potentiometric titration method. The formation constants of these complexes (expressed as lgK{sub BHB{sup +}}) have been determined in two non-aqueous aprotic solvents with different polarity, i.e., acetone (AC) and acetonitrile (AN). It has been observed that tri- and tetra-substituted pyridine N-oxides [B] and their cationic acids [BH{sup +}] form stable homocomplexed cations [BHB{sup +}] stabilized by O...H...O bridges in both solvents used. It has been found that the most stable homocomplexed system is formed by 3,5-dimethyl-4-chloropyridine N-oxide (3,5Me{sub 2}4ClPyO). The lgK{sub BHB{sup +}} values for this compound in acetone and acetonitrile are 3.15 and 2.82, respectively. Furthermore, by using ab initio methods at the RHF and MP2 levels utilizing the Gaussian 6-31++G{sup **} basis set, the energies of formation of the homocomplexed cations and Gibbs free energies have been determined in vacuo. The calculated energy parameters in vacuo have been compared with the cationic homoconjugation constants determined potentiometrically in acetone and acetonitrile to establish a correlation between these magnitudes. Additionally, the results of potentiometric measurements have been used to determine the acidity constants of the conjugate acids of N-oxides.

  12. Differential contribution of TRPM4 and TRPM5 nonselective cation channels to the slow afterdepolarization in mouse prefrontal cortex neurons

    Directory of Open Access Journals (Sweden)

    Ya-Ting eLei

    2014-09-01

    Full Text Available In certain neurons from different brain regions, a brief burst of action potentials can activate a slow afterdepolarization (sADP in the presence of muscarinic acetylcholine receptor agonists. The sADP, if suprathreshold, can contribute to persistent non-accommodating firing in some of these neurons. Previous studies have characterized a Ca2+-activated non-selective cation (CAN current (ICAN that is thought to underlie the sADP. ICAN depends on muscarinic receptor stimulation and exhibits a dependence on neuronal activity, membrane depolarization and Ca2+-influx similar to that observed for the sADP. Despite the widespread occurrence of sADPs in neurons throughout the brain, the molecular identity of the ion channels underlying these events, as well as ICAN, remains uncertain. Here we used a combination of genetic, pharmacological and electrophysiological approaches to characterize the molecular mechanisms underlying the muscarinic receptor-dependent sADP in layer 5 pyramidal neurons of mouse prefrontal cortex. First, we confirmed that in the presence of the cholinergic agonist carbachol a brief burst of action potentials triggers a prominent sADP in these neurons. Second, we confirmed that this sADP requires activation of a PLC signaling cascade and intracellular calcium signaling. Third, we obtained direct evidence that the transient receptor potential melastatin 5 channel (TRPM5, which is thought to function as a CAN channel in non-neural cells, contributes importantly to the sADP in the layer 5 neurons. In contrast, the closely related TRPM4 channel may play only a minor role in the sADP.

  13. Differential contribution of TRPM4 and TRPM5 nonselective cation channels to the slow afterdepolarization in mouse prefrontal cortex neurons.

    Science.gov (United States)

    Lei, Ya-Ting; Thuault, Sebastien J; Launay, Pierre; Margolskee, Robert F; Kandel, Eric R; Siegelbaum, Steven A

    2014-01-01

    In certain neurons from different brain regions, a brief burst of action potentials can activate a slow afterdepolarization (sADP) in the presence of muscarinic acetylcholine receptor agonists. The sADP, if suprathreshold, can contribute to persistent non-accommodating firing in some of these neurons. Previous studies have characterized a Ca(2+)-activated non-selective cation (CAN) current (ICAN ) that is thought to underlie the sADP. ICAN depends on muscarinic receptor stimulation and exhibits a dependence on neuronal activity, membrane depolarization and Ca(2+)-influx similar to that observed for the sADP. Despite the widespread occurrence of sADPs in neurons throughout the brain, the molecular identity of the ion channels underlying these events, as well as ICAN , remains uncertain. Here we used a combination of genetic, pharmacological and electrophysiological approaches to characterize the molecular mechanisms underlying the muscarinic receptor-dependent sADP in layer 5 pyramidal neurons of mouse prefrontal cortex. First, we confirmed that in the presence of the cholinergic agonist carbachol a brief burst of action potentials triggers a prominent sADP in these neurons. Second, we confirmed that this sADP requires activation of a PLC signaling cascade and intracellular calcium signaling. Third, we obtained direct evidence that the transient receptor potential (TRP) melastatin 5 channel (TRPM5), which is thought to function as a CAN channel in non-neural cells, contributes importantly to the sADP in the layer 5 neurons. In contrast, the closely related TRPM4 channel may play only a minor role in the sADP.

  14. An efficient nonviral gene-delivery vector based on hyperbranched cationic glycogen derivatives

    Directory of Open Access Journals (Sweden)

    Liang X

    2014-01-01

    rats was evaluated to identify the safety and transfection efficiency. Results: The hyperbranched cationic glycogen derivatives conjugated with DMAPA and AEPZ residues were synthesized. They exhibited better blood compatibility and lower cytotoxicity when compared to branched polyethyleneimine (bPEI. They were able to bind and condense pDNA to form the complexes of 100–250 nm in size. The transfection efficiency of the DMAPA-Glyp/pDNA complexes was higher than those of the AEPZ-Glyp/pDNA complexes in both the 293T and CNE2 cells, and almost equal to those of bPEI. Furthermore, pDNA could be more safely delivered to the blood vessels in brain tissue of Sprague Dawley rats by the DMAPA-Glyp derivatives, and then expressed as green fluorescence protein, compared with the control group. Conclusion: The hyperbranched cationic glycogen derivatives, especially the DMAPA-Glyp derivatives, showed high gene-transfection efficiency, good blood compatibility, and low cytotoxicity when transfected in vitro and in vivo, which are novel potential nonviral gene vectors. Keywords: glycogen, blood compatibility, cytotoxicity, gene delivery

  15. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Kessel, Markus Franz

    2012-01-01

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO 3 single crystals has been studied by means of 18 O 2 / 16 O 2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The

  16. On good ETOL forms

    DEFF Research Database (Denmark)

    Skyum, Sven

    1978-01-01

    This paper continues the study of ETOL forms and good EOL forms done by Maurer, Salomaa and Wood. It is proven that binary very complete ETOL forms exist, good synchronized ETOL forms exist and that no propagating or synchronized ETOL form can be very complete.......This paper continues the study of ETOL forms and good EOL forms done by Maurer, Salomaa and Wood. It is proven that binary very complete ETOL forms exist, good synchronized ETOL forms exist and that no propagating or synchronized ETOL form can be very complete....

  17. Mechanically driven activation of polyaniline into its conductive form.

    Science.gov (United States)

    Baytekin, Bilge; Baytekin, H Tarik; Grzybowski, Bartosz A

    2014-07-01

    Mechanical treatment of polymers produces surface cations and anions which, as demonstrated here for the first time, can drive chemical reactions. In particular, it is shown that such a mechanical treatment transforms nonconductive polyaniline into its conductive form. These results provide a mechanical means of patterning conductive polymers and also coating small polymer objects with conductive polyaniline films preventing accumulation of static electricity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Cationic and neutral copper (I) iodide cluster MOFs derived from ...

    Indian Academy of Sciences (India)

    By utilizing L¹, a cationic 2D-MOF {[(L¹) ₂ (Cu₆I₅)](OH) · 3DMF·4MeOH}n, 1 containing a rugby ball shaped discrete Cu₆I₅ cluster has been reported earlier. Formation of a new 3D-MOF {[(L²) ₂ (Cu₆I₄)](OH) ₂· 2DMF}n containing a Zintl type [(Cu₆I₄4) ² ⁺]n cluster chains is reported in this paper. A neutral cluster MOFs ...

  19. Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang; Alivisatos, A. Paul

    2007-03-14

    Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.

  20. Magnesium isotope fractionation in cation-exchange chromatography

    International Nuclear Information System (INIS)

    Oi, T.; Yanase, S.; Kakihana, H.

    1987-01-01

    Band displacement chromatography of magnesium has been carried out successfully for the purpose of magnesium isotope separation by using a strongly acidic cation-exchange resin and the strontium ion as the replacement ion. A small but definite accumulation of the heavier isotopes ( 25 Mg, 26 Mg) has been observed at the front parts of the magnesium chromatograms. The heavier isotopes have been fractionated preferentially into the solution phase. The single-stage separation factors have been calculated for the 25 Mg/ 24 Mg and 26 Mg/ 24 isotopic pairs at 25 0 C. The reduced partition function ratios of magnesium species involved in the present study have been estimated

  1. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.

    2014-01-01

    with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both......Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...

  2. Applications of pressurized cation exchange chromatography for fission yield determination

    International Nuclear Information System (INIS)

    Yan Shuheng; Lin Fa; Zhang Hongdi; Li Xueliang; Zhang Shulan

    1988-01-01

    In order to determine the fission yields of lanthanides precisely, lanthanides with carriers of 1-2 mg per element are separated from each other by means of pressurized cation exchange chromatography - αHIBA concentration gradient elution. The effect of initial loading technique, concentration gradient, flow rate, and temperature on separation were investigated in detail. Under the optimum conditions adapted according to the results given in this work, all the lanthanides can be completely separated within about 90 minutes with a recovery of more than 95% and purity higher than 99%. (author) 3 refs.; 6 figs

  3. Peak metamorphic temperatures from cation diffusion zoning in garnet

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik; Mezger, Klaus

    2013-01-01

    is robust and provides a reliable means of estimating peak temperatures for different types of high-grade metamorphic rock. The tool could be of particular advantage in rocks where critical assemblages for conventional thermometry do not occur or have been replaced during retrogression.......) to develop a tool that uses the diffusion zoning of these cations in garnet to constrain peak temperature conditions for garnet-bearing rocks. The thermometric approach was externally tested by applying it to garnet crystals from various metamorphic terranes worldwide and comparing the results to published...

  4. Mass analyzed threshold ionization spectroscopy of indazole cation

    Science.gov (United States)

    Su, Huawei; Pradhan, Manik; Tzeng, Wen Bih

    2005-08-01

    We have recorded the two-color resonant two-photon mass analyzed threshold ionization (MATI) spectra of indazole via four intermediate states. The adiabatic ionization energy of this molecule is determined to be 67 534 ± 5 cm -1. The observed MATI bands include in-plane ring bending as well as out-of-plane ring twisting and bending vibrations of the indazole cation. Comparing the present data with those of indole and 7-azaindole leads to a better understanding about the influence of the nitrogen atom in the aza-aromatic bicyclic system.

  5. Elemental composition of some essential cations in human ocular tissue

    Energy Technology Data Exchange (ETDEWEB)

    Panessa-Warren, B.J.; Kraner, H.W.; Warren, J.B.

    1983-01-01

    To obtain data on the baseline elemental content in normal adult sensory retina, RPE and iris, normal non-diabetic eyes were analyzed and these results were used for comparison to similarly prepared samples from diabetic donor eyes. To determine if the concentrations of the cations, Ca, Ba and Zn were altered by the age, alimentation and exposure to light of the donor, tissue from children (from 25 weeks gestation to 8-1/2 years old) was also analyzed by x-ray fluorescence spectroscopy, proton induced x-ray emission spectroscopy, and light and electron (scanning and transmission) microscopy.

  6. Interaction of ethidium and tetraphenylphosphonium cations with Salmonella enterica cells

    Directory of Open Access Journals (Sweden)

    Valeryia Mikalayeva

    2017-01-01

    Conclusions: Results of our experiments indicate that ionic strength of the incubation medium influence the selectivity, the medium temperature and the assay conditions impact the kinetics of efflux. The lower accumulated amount and the weaker fluorescence of Et+ registered in slightly acidic medium indicate that ΔΨ plays a role in the accumulation of this indicator cation. The bound amount of Et+ to the de-energized or permeabilized cells considerably varies depending on the conditions and methods of de-energization or permeabilization of cells. Tris/EDTA permeabilization of the cells does not inhibit the efflux.

  7. The ionic conductivity and local environment of cations in Bi9ReO17

    International Nuclear Information System (INIS)

    Thompson, M.; Herranz, T.; Santos, B.; Marco, J.F.; Berry, F.J.; Greaves, C.

    2010-01-01

    The influence of temperature on the structure of Bi 9 ReO 17 has been investigated using differential thermal analysis, variable temperature X-ray diffraction and neutron powder diffraction. The material undergoes an order-disorder transition at ∼1000 K on heating, to form a fluorite-related phase. The local environments of the cations in fully ordered Bi 9 ReO 17 have been investigated by Bi L III - and Re L III -edge extended X-ray absorption fine structure (EXAFS) measurements to complement the neutron powder diffraction information. Whereas rhenium displays regular tetrahedral coordination, all bismuth sites show coordination geometries which reflect the importance of a stereochemically active lone pair of electrons. Because of the wide range of Bi-O distances, EXAFS data are similar to those observed for disordered structures, and are dominated by the shorter Bi-O bonds. Ionic conductivity measurements indicate that ordered Bi 9 ReO 17 exhibits reasonably high oxide ion conductivity, corresponding to 2.9x10 -5 Ω -1 cm -1 at 673 K, whereas the disordered form shows higher oxide ion conductivity (9.1x10 -4 Ω -1 cm -1 at 673 K). - Graphical abstract: The structure of Bi 9 ReO 17 is discussed and related to the ionic conductivity of the ordered and disordered forms.

  8. Probing Induced Structural Changes in Biomimetic Bacterial Cell Membrane Interactions with Divalent Cations

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Allison M [ORNL; Standaert, Robert F [ORNL; Jubb, Aaron M [ORNL; Katsaras, John [ORNL; Johs, Alexander [ORNL

    2017-01-01

    Biological membranes, formed primarily by the self-assembly of complex mixtures of phospholipids, provide a structured scaffold for compartmentalization and structural processes in living cells. The specific physical properties of phospholipid species present in a given membrane play a key role in mediating these processes. Phosphatidylethanolamine (PE), a zwitterionic lipid present in bacterial, yeast, and mammalian cell membranes, is exceptional. In addition to undergoing the standard lipid polymorphic transition between the gel and liquid-crystalline phase, it can also assume an unusual polymorphic state, the inverse hexagonal phase (HII). Divalent cations are among the factors that drive the formation of the HII phase, wherein the lipid molecules form stacked tubular structures by burying the hydrophilic head groups and exposing the hydrophobic tails to the bulk solvent. Most biological membranes contain a lipid species capable of forming the HII state suggesting that such lipid polymorphic structural states play an important role in structural biological processes such as membrane fusion. In this study, the interactions between Mg2+ and biomimetic bacterial cell membranes composed of PE and phosphatidylglycerol (PG) were probed using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), and fluorescence spectroscopy. The lipid phase transitions were examined at varying ratios of PE to PG and upon exposure to physiologically relevant concentrations of Mg2+. An understanding of these basic interactions enhances our understanding of membrane dynamics and how membrane-mediated structural changes may occur in vivo.

  9. Efficient gene delivery to human umbilical cord mesenchymal stem cells by cationized Porphyra yezoensis polysaccharide nanoparticles

    Directory of Open Access Journals (Sweden)

    Yu Q

    2015-11-01

    Full Text Available Qingtong Yu,1,2 Jin Cao,2 Baoding Chen,3 Wenwen Deng,2 Xia Cao,2 Jingjing Chen,2 Yan Wang,2 Shicheng Wang,2 Jiangnan Yu,2 Ximing Xu,2 Xiangdong Gao1 1School of Life Science and Technology, China Pharmaceutical University, Nanjing, 2Department of Pharmaceutics, School of Pharmacy and Center for Drug/Gene Delivery and Tissue Engineering, Jiangsu University, 3Department of Medical Ultrasound, Affiliated Hospital of Jiangsu University, Zhenjiang, People’s Republic of China Abstract: This study centered on an innovative application of Porphyra yezoensis polysaccharide (PPS with cationic modification as a safe and efficient nonviral gene vector to deliver a plasmid encoding human Wnt3a (pWnt3a into human umbilical cord mesenchymal stem cells (HUMSCs. After modification with branched low-molecular-weight (1,200 Da polyethylenimine, the cationized PPS (CPPS was combined with pWnt3a to form spherical nanoscale particles (CPPS-pWnt3a nanoparticles. Particle size and distribution indicated that the CPPS-pWnt3a nanoparticles at a CPPS:pWnt3a weight ratio of 40:1 might be a potential candidate for DNA plasmid transfection. A cytotoxicity assay demonstrated that the nanoparticles prepared at a CPPS:pWnt3a weight ratio of 40:1 were nontoxic to HUMSCs compared to those of Lipofectamine 2000 and polyethylenimine (25 kDa. These nanoparticles were further transfected to HUMSCs. Western blotting demonstrated that the nanoparticles (CPPS:pWnt3a weight ratio 40:1 had the greatest transfection efficiency in HUMSCs, which was significantly higher than that of Lipofectamine 2000; however, when the CPPS:pWnt3a weight ratio was increased to 80:1, the nanoparticle-treated group showed no obvious improvement in translation efficiency over Lipofectamine 2000. Therefore, CPPS, a novel cationic polysaccharide derived from P. yezoensis, could be developed into a safe, efficient, nonviral gene vector in a gene-delivery system. Keywords: Porphyra yezoensis, nanoparticle

  10. The effects of trace elements, cations, and environmental conditions on protocatechuate 3,4-dioxygenase activity

    Directory of Open Access Journals (Sweden)

    Andréa Scaramal da Silva

    2013-04-01

    Full Text Available Phenanthracene is a highly toxic organic compound capable of contaminating water and soils, and biodegradation is an important tool for remediating polluted environments. This study aimed to evaluate the effects of trace elements, cations, and environmental conditions on the activity of the protocatechol 3,4-dioxygenase (P3,4O enzyme produced by the isolate Leifsonia sp. in cell-free and immobilized extracts. The isolate was grown in Luria Bertani broth medium (LB amended with 250 mg L-1 of phenanthrene. Various levels of pH (4.0-9.0, temperature (5-80 °C, time (0-90 min, trace elements (Cu2+, Hg2+ and Fe3+, and cations (Mg2+, Mn2+, K+ and NH4+ were tested to determine which conditions optimized enzyme activity. In general, the immobilized extract exhibited higher enzyme activity than the cell-free extract in the presence of trace elements and cations. Adding iron yielded the highest relative activity for both cell-free and immobilized extracts, with values of 16 and 99 %, respectively. Copper also increased enzyme activity for both cell-free and immobilized extracts, with values of 8 and 44 %, respectively. Enzyme activity in the phosphate buffer was high across a wide range of pH, reaching 80 % in the pH range between 6.5 and 8.0. The optimum temperatures for enzyme activity differed for cell-free and immobilized extracts, with maximum enzyme activity observed at 35 ºC for the cell-free extract and at 55 ºC for the immobilized extract. The cell-free extract of the P3,4O enzyme exhibited high activity only during the first 3 min of incubation, when it showed 50 % relative activity, and dropped to 0 % after 60 min of incubation. By contrast, activity in the immobilized extract was maintained during 90 min of incubation. This isolate has important characteristics for phenanthrene biodegradation, producing high quantities of the P3,4O enzyme that forms part of the most important pathway for PAH biodegradation.

  11. Electrochemical investigations on cation-cation interaction between Np(V) and U(VI) in nitric acid medium

    International Nuclear Information System (INIS)

    Verma, P.K.; Murali, M.S.; Pathak, P.N.; Mohapatra, P.K.

    2014-01-01

    Ever since the first report on cation-cation interactions (CCIs) in 1961 by Sullivan et al., many researchers have worked on this using different techniques like optical spectroscopy and potentiometry. However, there is almost no report, in recent times, on this interesting subject using an electrochemical technique. In the present work, we set out to use simple cyclic voltammetry (CV) as a probe to study this phenomenon in the case of Np(V)-U(VI) in nitric acid medium. Accordingly, cyclic voltammograms were recorded individually for Np(V) , U(VI) in 4M HNO 3 and for solutions resulting from a titration of Np(V) with incremental additions of U(VI) in the same medium. These experiments were carried out using AutoLab 30 with three solid electrode system. Ag/AgCl was the reference electrode while Pt wires were used as working and counter electrode. The paper gives the part of CVs for successive additions of only U(VI) (1.4M) at fixed scan rate and room temperature. It can be seen that that the reduction peak shifts only slightly towards left with increased aliquots of U(VI). In contrast, the paper also gives the part of CVs for only U(VI) and for a titration mixture of fixed concentration of Np(V) and successive volume aliquot-additions of U(VI). It can be seen that there was no appreciable shift in the cathodic peak (∼ -0.15V) for additions of 1225μL of only U(VI) and 3225 μL of U(VI) in presence of Np. This showed that no change occurred till this composition. But with the addition of next aliquot of 4225μL of U(VI), there was an appreciable shift in the peak. This signified the formation of a new complex which can be attributed to the cation-cation interaction envisaged for Np(V)-U(VI). With further addition of an aliquot of 4725 μL of U(VI), it can be seen that again there was no appreciable shift in the cathodic peak position which probably underlined that the formation of the complex was complete

  12. Evidence for the Formation of Pyrimidine Cations from the Sequential Reactions of Hydrogen Cyanide with the Acetylene Radical Cation.

    Science.gov (United States)

    Hamid, Ahmed M; Bera, Partha P; Lee, Timothy J; Aziz, Saadullah G; Alyoubi, Abdulrahman O; El-Shall, M Samy

    2014-10-02

    Herein, we report the first direct evidence for the formation of pyrimidine ion isomers by sequential reactions of HCN with the acetylene radical cation in the gas phase at ambient temperature using the mass-selected variable temperature and pressure ion mobility technique. The formation and structures of the pyrimidine ion isomers are theoretically predicted via coupled cluster and density functional theory calculations. This ion-molecule synthesis may indicate that pyrimidine is produced in the gas phase in space environments before being incorporated into condensed-phase ices and transformed into nucleic acid bases such as uracil.

  13. Crystal structure of the channelrhodopsin light-gated cation channel

    Science.gov (United States)

    Kato, Hideaki E.; Zhang, Feng; Yizhar, Ofer; Ramakrishnan, Charu; Nishizawa, Tomohiro; Hirata, Kunio; Ito, Jumpei; Aita, Yusuke; Tsukazaki, Tomoya; Hayashi, Shigehiko; Hegemann, Peter; Maturana, Andrés D.; Ishitani, Ryuichiro; Deisseroth, Karl; Nureki, Osamu

    2014-01-01

    Channelrhodopsins (ChRs) are light-gated cation channels derived from algae that have shown experimental utility in optogenetics; for example, neurons expressing ChRs can be optically controlled with high temporal precision within systems as complex as freely moving mammals. Although ChRs have been broadly applied to neuroscience research, little is known about the molecular mechanisms by which these unusual and powerful proteins operate. Here we present the crystal structure of a ChR (a C1C2 chimaera between ChR1 and ChR2 from Chlamydomonas reinhardtii) at 2.3 Å resolution. The structure reveals the essential molecular architecture of ChRs, including the retinal-binding pocket and cation conduction pathway. This integration of structural and electrophysiological analyses provides insight into the molecular basis for the remarkable function of ChRs, and paves the way for the precise and principled design of ChR variants with novel properties. PMID:22266941

  14. Crystal structures of the TRIC trimeric intracellular cation channel orthologues.

    Science.gov (United States)

    Kasuya, Go; Hiraizumi, Masahiro; Maturana, Andrés D; Kumazaki, Kaoru; Fujiwara, Yuichiro; Liu, Keihong; Nakada-Nakura, Yoshiko; Iwata, So; Tsukada, Keisuke; Komori, Tomotaka; Uemura, Sotaro; Goto, Yuhei; Nakane, Takanori; Takemoto, Mizuki; Kato, Hideaki E; Yamashita, Keitaro; Wada, Miki; Ito, Koichi; Ishitani, Ryuichiro; Hattori, Motoyuki; Nureki, Osamu

    2016-12-01

    Ca 2+ release from the sarcoplasmic reticulum (SR) and endoplasmic reticulum (ER) is crucial for muscle contraction, cell growth, apoptosis, learning and memory. The trimeric intracellular cation (TRIC) channels were recently identified as cation channels balancing the SR and ER membrane potentials, and are implicated in Ca 2+ signaling and homeostasis. Here we present the crystal structures of prokaryotic TRIC channels in the closed state and structure-based functional analyses of prokaryotic and eukaryotic TRIC channels. Each trimer subunit consists of seven transmembrane (TM) helices with two inverted repeated regions. The electrophysiological, biochemical and biophysical analyses revealed that TRIC channels possess an ion-conducting pore within each subunit, and that the trimer formation contributes to the stability of the protein. The symmetrically related TM2 and TM5 helices are kinked at the conserved glycine clusters, and these kinks are important for the channel activity. Furthermore, the kinks of the TM2 and TM5 helices generate lateral fenestrations at each subunit interface. Unexpectedly, these lateral fenestrations are occupied with lipid molecules. This study provides the structural and functional framework for the molecular mechanism of this ion channel superfamily.

  15. Source of Lake Vostok Cations Constrained with Strontium Isotopes

    Directory of Open Access Journals (Sweden)

    William Berry Lyons

    2016-08-01

    Full Text Available Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.

  16. Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry.

    Science.gov (United States)

    Silva, Eduarda M P; Serra, Vanda Vaz; Ribeiro, Anderson O; Tomé, João P C; Domingues, Pedro; Faustino, M Amparo F; Neves, M Graça P M S; Tomé, Augusto C; Cavaleiro, José A S; Ferrer-Correia, António J; Iamamoto, Yassuko; Domingues, M Rosário M

    2006-01-01

    Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI-MS/MS). The electrospray mass spectra (ESI-MS) show the M(+) ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI-MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (-163 or -243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (-162 or -242 Da) and cross-ring fragmentations typical of glyco-derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic beta-pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C(5)-C(6) bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI-MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit. Copyright (c) 2006 John Wiley & Sons, Ltd.

  17. Effects of cation concentration on photocatalytic performance over magnesium vanadates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Zhou, Wei [Department of Physics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); Wang, Xin; Zhang, Yan; Wang, Defa [TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); Umezawa, Naoto, E-mail: UMEZAWA.Naoto@nims.go.jp, E-mail: ABE.Hideki@nims.go.jp; Abe, Hideki, E-mail: UMEZAWA.Naoto@nims.go.jp, E-mail: ABE.Hideki@nims.go.jp [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ye, Jinhua [Catalytic Materials Group, Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-10-01

    A series of magnesium vanadates (MgV {sub 2}O{sub 6}, Mg{sub 2}V {sub 2}O{sub 7}, and Mg{sub 3}V {sub 2}O{sub 8}) were synthesized to investigate the effect of cation concentration on photocatalytic performance. The samples were characterized by X-ray diffraction, field emission-scanning electron microscopy, UV-visible diffuse reflectance spectroscopy, and fluorescence spectroscopy. The photocatalytic O{sub 2} evolution experiments under visible light irradiation showed Mg{sub 2}V {sub 2}O{sub 7} exhibits the best performance, while Mg{sub 3}V {sub 2}O{sub 8} has the lowest activity. The density functional theory calculations indicated that the lowest unoccupied states of Mg{sub 3}V {sub 2}O{sub 8} are the mostly localized by the cation layers. The fluorescence spectra and fluorescence decay curves gave evident performances of excited states of magnesium vanadates and pointed out MgV {sub 2}O{sub 6} has a very short excited electron lift-time. Mg{sub 2}V {sub 2}O{sub 7} performs high photocatalytic activity because of its high electron mobility and long electron life-time.

  18. Correlation between cationic lipid-based transfection and cell division

    Energy Technology Data Exchange (ETDEWEB)

    Kirchenbuechler, Inka; Kirchenbuechler, David; Elbaum, Michael, E-mail: michael@elbaum.ac.il

    2016-07-01

    We evaluate the temporal relation between protein expression by cationic lipid-mediated transfection and cell division using time lapse fluorescence microscopy. Detailed image analysis provides new insights on the single cell level while simultaneously achieving appropriate statistics. Earlier evidence by less direct methods such as flow cytometry indicates a primary route for transfection involving nuclear envelope breakdown, but also suggests the existence of a pathway independent of mitosis. We confirm and quantify both mechanisms. We found the timing for successful transfection to be unexpectedly flexible, contrary to assertions of a narrow time window. Specifically, cells dividing more than 24 h after exposure to the transfection medium express the probed protein at a comparable level to cells in a mitotic state during or shortly after transfection. This finding can have a profound impact on the guidance and development of non-viral gene delivery materials. - Highlights: • Cationic lipid-based transfection supports protein expression without cell division. • Protein expression is unrelated to cell cycle status at the time of transfection. • Time-lapse imaging provides direct evaluation without statistical averaging. • Lipoplex dissociation is a likely target for improvement of transfection efficiency.

  19. Stretch-activated cation channel from larval bullfrog skin

    DEFF Research Database (Denmark)

    Hillyard, Stanley D; Willumsen, Niels J; Marrero, Mario B

    2010-01-01

    Cell-attached patches from isolated epithelial cells from larval bullfrog skin revealed a cation channel that was activated by applying suction (-1 kPa to -4.5 kPa) to the pipette. Activation was characterized by an initial large current spike that rapidly attenuated to a stable value and showed...... was markedly reduced with N-methyl-D-glucamide (NMDG)-Cl Ringer's solution in the pipette. Neither amiloride nor ATP, which are known to stimulate an apical cation channel in Ussing chamber preparations of larval frog skin, produced channel activation nor did these compounds affect the response to suction....... Stretch activation was not affected by varying the pipette concentrations of Ca(2+) between 0 mmol l(-1) and 4 mmol l(-1) or by varying pH between 6.8 and 8.0. However, conductance was reduced with 4 mmol l(-1) Ca(2+). Western blot analysis of membrane homogenates from larval bullfrog and larval toad skin...

  20. Coordination phenomena of cationic uranium(iv) complexes

    International Nuclear Information System (INIS)

    Rohwer, H.E.

    1974-12-01

    The coordination properties of the cationic uranium(IV) complexes UCl 3 + , UCl 2 2+ , UCl 3+ , and U 4+ were studied in a non-aqueous medium in the presence of perchlorate as counterion which, however, proved to coordinate to a much greater extent than expected. The strong neutral ligand, HMPA, could successively displace some of the perchlorates. An electrostatic model for the U(CIO 4 ) 4 -HMPA-acetone system compared favourably with the actual results. This emphasized the high ionic content in the bonding with actenoid cations, even with such a high charge as +4 . These conclusions are in agreement with studies 75 in which nitrate acts as counter ion. Correspondingly the uranium (IV) chemistry is characterized by the absence of typical 3d-organometallic chemistry, for example, strong bonding with CO, P(Phi) 3 etc, which strongly depends on covalent bonding. This stresses the fact that the d and f orbitals are not readily available for strong bond formation with the actenoids. 76