Presence Of Halide Ions Research Articles

Possibilities for the diagnosis of inflammatory reaction in ischemic stroke

To study diagnostic possibilities for determining the content of nitrite and N-nitroso compounds (NO2-+RNNO) in blood plasma and cerebrospinal fluid (CSF) in patients with acute ischemic stroke (IS). Twenty-four patients with IS were examined. The content of NO oxidation products was determined in venous blood and CSF by using an enzyme sensor based on the unique property of nitrite (NO2-), N-nitroso compounds (RNNO), S-nitrosothiols and dinitrosyl iron complexes to inhibit the enzyme catalase in the presence of halide ions. The study was conducted on the 1st day of IS. CSF in patients with IS contained nitrite and N-nitroso compounds (NO2-+RNNO) in concentrations ranging from 0.4 to 2.0 µm. The relationship between the size of IS and the concentration of NO2-+RNNO in CSF was shown. It was 1.01±0.13 µm in patients with medium IS and 0.71±0.07 µm in patients with small IS (U-criterion 16.5; p<0.05). There was no correlation between the severity of neurological deficit at the time of hospitalization and discharge from the hospital and the content of NO2-+RNNO in CSF (r=0.134; p>0.5; r=0.155; p>0.5, respectively). Plasma NO2-+RNNO levels were not associated with the presence and size of IS though they were elevated in patients with inflammatory complications. In conclusion, NO2-+RNNO can be considered as a marker of inflammation in patients with IS. Their presence in CSF reflects the extent of brain damage, but not the presence of concomitant inflammatory diseases.

Single Oxidative Collision Events of Silver Nanoparticles: Understanding the Rate-Determining Chemistry.

The oxidative dissolution of citrate-capped silver nanoparticles (AgNPs, ∼50 nm diameter) is investigated herein by two electrochemical techniques: nano-impacts and anodic stripping voltammetry. Nano-impacts or single nanoparticle-electrode collisions allow the detection of individual nanoparticles. The technique offers an advantage over surface-immobilized methods such as anodic stripping voltammetry as it eliminates the effects of particle agglomeration/aggregation. The electrochemical studies are performed in different electrolytes (KNO3 , KCl, KBr and KI) at varied concentrations (≤20 mm). In nano-impact measurements, the AgNP undergoes complete oxidation upon impact at a suitably potentiostated electrode. The frequency of the nanoparticle-electrode collisions observed as current-transient spikes depends on the electrolyte identity, its concentration and the potential applied at the working electrode. The frequencies of the spikes are significantly higher in the presence of halide ions and increase with increasing potentials. From the frequency, the rate of AgNP oxidation as compared with the timescale the AgNP is in electrical contact with the electrode can be inferred, and hence is indicative of the relative kinetics of the oxidation process. Primarily based on these results, we propose the initial formation of the silver (I) nucleus (Ag+ , AgCl, AgBr or AgI) as the rate-determining process of silver oxidation on the nanoparticle.

Size, Shape, and Phase Control in Ultrathin CdSe Nanosheets.

Ultrathin two-dimensional nanosheets raise a rapidly increasing interest due to their unique dimensionality-dependent properties. Most of the two-dimensional materials are obtained by exfoliation of layered bulk materials or are grown on substrates by vapor deposition methods. To produce free-standing nanosheets, solution-based colloidal methods are emerging as promising routes. In this work, we demonstrate ultrathin CdSe nanosheets with controllable size, shape, and phase. The key of our approach is the use of halogenated alkanes as additives in a hot-injection synthesis. Increasing concentrations of bromoalkanes can tune the shape from sexangular to quadrangular to triangular and the phase from zinc blende to wurtzite. Geometry and crystal structure evolution of the nanosheets take place in the presence of halide ions, acting as cadmium complexing agents and as surface X-type ligands, according to mass spectrometry and X-ray photoelectron spectroscopies. Our experimental findings show that the degree of these changes depends on the molecular structure of the halogen alkanes and the type of halogen atom.

Synergistic Effect of Halide Ions on the Corrosion Inhibition of Zinc in Hydrochloric Acid using Schiff base compound, 1-phenyl-2, 3-dimethyl-4-(benzylamino)pyrazole-5-one

The inhibitive effect of1-phenyl-2,3-dimethyl-4-(benzylamino) pyrazole-5-one (PD(B)PO) on zinc corrosion in 0.1 M hydrochloric acid solution was studied using gravimetric method. The influence of halides viz., KCl, KBr and KI on the corrosion inhibition of PD(B)PO were also investigated. Results show that PD(B)PO alone provided satisfactory inhibition on the corrosion of zinc and it was also found that the inhibition efficiency increased synergistically in the presence of halide ions. The synergistic effect of halide ions was found to follow the order: KI > KBr > KCl. The inhibitor reduced the corrosion rate through adsorption process and obeyed the Freundlich adsorption isotherm.

Protein-Modified CuS Nanotriangles: A Potential Multimodal Nanoplatform for In Vivo Tumor Photoacoustic/Magnetic Resonance Dual-Modal Imaging.

Controllable preparation of water-soluble multifunctional nanoprobes is of great significance for cancer early diagnosis. In this study, protein-modified hydrophilic copper sufide (CuS) nanotriangles with tunable absorption in the second near-infrared region are developed in the presence of halide ions. Further, gadolinium ions chelated diethylenetriaminepentaacetic acid is conjugated on it by using the unique characteristics of the protein-protected nanotriangles. Specifically, the as-obtained nanostructures are investigated as contrast agents for enhanced in vivo photoacoustic/magnetic resonance dual-modal tumor imaging. More importantly, in vitro and in vivo toxicity analysis are also performed, which show that the dual-modal nanoprobes are biocompatible for most of the cases. It is demonstrated that the novel as-prepared protein-modified nanotriangles are able to work as a nanoplatform to construct dual-modal nanoprobes, which paves a new avenue for improving the photoacoustic/magnetic resonance imaging contrast in cancer detection. It should be pointed out that other functional blocks may also be linked on it, which makes it a general method to design multifunctional nanoprobes.

Aqueous secondary formation of brominated, chlorinated, and mixed halogenated pyrene in presence of halide ions

We examined the secondary production of halogenated derivatives of polycyclic aromatic hydrocarbons (PAHs) in surface seawater. Pyrene was selected as the model compound and exposed to UV irradiation in synthetic seawater for various irradiation times. Pyrene underwent rapid photochemical reactions that produced various halogenated derivatives including 1-chloropyrene, 1-bromopyrene, three unidentified dichloropyrenes, and three unidentified bromochloropyrenes. The production of 1-chloropyrene (220–360 nM) was higher than that of 1-bromopyrene (7.3–12 nM), reflecting the high chlorine content of seawater. A pilot field survey was conducted to test the environmental implications of these results, and fresh, brackish, and seawater samples were collected in southwestern Japan. The variation in the concentration ratios between 1-chloropyrene and pyrene implied the presence of a specific source of 1-chloropyrene in coastal water, which can be partly explained by the secondary production observed in our photolysis experiments. In sum, the photochemical reactions of PAHs are a potential secondary source of halogenated PAHs, especially in marine environments heavily contaminated with PAHs.

Electrochemical dissolution of gold in presence of chloride and bromide traces studied by on-line electrochemical inductively coupled plasma mass spectrometry

Electrochemical dissolution of gold in the presence of halide ions is traditionally considered as a model case in metal corrosion and passivation studies. Due to a relatively low sensitivity of the conventional techniques, such studies were predominantly limited to electrolytes with high concentrations of halides. The current work employs a special electrochemical scanning flow cell with online inductively coupled plasma mass spectrometry (SFC-ICP-MS) that allows overcoming those limitations, enabling the quantification of gold dissolution in the presence of chloride and bromide traces (1μM≤[Cl−/Br−]≤100μM). Moreover, time- and potential-resolved gold dissolution profiles under different potential programs are provided. Based on the experimental results, a tentative mechanism of gold dissolution based on the catalyzing role of hydroxyl and halide anions is discussed.

A halogen-free synthesis of gold nanoparticles using gold(III) oxide.

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-016-3576-x) contains supplementary material, which is available to authorized users.

Influence of Halide Ions on Anodic Oxidation of Ethanol on Palladium

Ethanol oxidation on polycrystalline palladium electrodes in alkaline media was studied in the presence of halide ions. Addition of halide ions decreased the ethanol oxidation peak current monotonically as a function of increasing halide concentration. The extent of poisoning was found to be in the order I− > Br− > Cl−. Thus, Cl− ions show appreciable inhibition of ethanol oxidation peak current at [Cl−] ~ 10−3 M, whereas Br− and I− inhibit ethanol oxidation even at [Br−] or [I−] ~ 10−6 M. The potential of the ethanol oxidation peak shifted positive with increasing halide ion concentration. The extent of the shift was found to be in the order I− > Br− > Cl−. This study is relevant due to the widespread use of palladium halide complexes in the production of Pd electrocatalysts for ethanol oxidation and other electrocatalytic reactions.

Mechanistic study on the facet etching effect of silver nanoprisms in the presence of halide ions and their application in the colorimetric sensing of metformin hydrochloride

The driving force of halide ions etching on Ag nanoprisms is the formation of a precipitant with Ag+ at the [110] facet.

Comparison of UV/hydrogen peroxide and UV/peroxydisulfate processes for the degradation of humic acid in the presence of halide ions.

This study compared the behaviors of two classic advanced oxidation processes (AOPs), hydroxyl radical-based AOPs ((•)OH-based AOPs) and sulfate radical-based AOPs (SO4 (•-)-based AOPs), represented by UV/ hydrogen peroxide (H2O2) and UV/peroxydisulfate (PDS) systems, respectively, to degrade humic acid (HA) in the presence of halide ions (Cl(-) and Br(-)). The effects of different operational parameters, such as oxidant dosages, halide ions concentration, and pH on HA degradation were investigated in UV/H2O2/Cl(-), UV/PDS/Cl(-), UV/H2O2/Br(-), and UV/PDS/Br(-) processes. It was found that the oxidation capacity of H2O2 and PDS to HA degradation in the presence of halides was nearly in the same order. High dosage of peroxides would lead to an increase in HA removal while excess dosage would slightly inhibit the efficiency. Both Cl(-) and Br(-) would have depressing impact on the two AOPs, but the inhibiting effect of Br(-) was more obvious than that of Cl(-), even the concentration of Cl(-) was far above that of Br(-). The increasing pH would have an adverse effect on HA decomposition in UV/H2O2 system, whereas there was no significant impact of pH in UV/PDS process. Furthermore, infrared spectrometer was used to provide the information of degraded HA in UV/H2O2/Cl(-), UV/PDS/Cl(-), UV/H2O2/Br(-), and UV/PDS/Br(-) processes, and halogenated byproducts were identified in using GC-MS analysis in the four processes. The present research might have significant technical implications on water treatment using advanced oxidation technologies.

Synthesis of [188ReX(CO)5] (X = Cl, Br, and I)

Radiochemically pure [188ReX(CO)5] (X = Cl, Br, and I) were prepared for the first time by high-pressure carbonylation of 188ReO4 − with carbon monoxide in an aqueous solution in the presence of halide ions at 210 °C. The complexes were isolated at the n.c.a. level from the reaction mixture by gas-phase transport with carbon monoxide at a high pressure. The procedure allows obtaining the target compounds in any appropriate solvent (aqueous and nonaqueous), which may open new synthetic prospects for the development of novel therapeutic radiopharmaceuticals.

Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions

The catalytic reaction of copper amine oxidase proceeds through a ping-pong mechanism comprising two half-reactions. In the initial half-reaction, the substrate amine reduces the Tyr-derived cofactor, topa quinone (TPQ), to an aminoresorcinol form (TPQamr) that is in equilibrium with a semiquinone radical (TPQsq) via an intramolecular electron transfer to the active-site copper. We have analyzed this reductive half-reaction in crystals of the copper amine oxidase from Arthrobacter globiformis. Anerobic soaking of the crystals with an amine substrate shifted the equilibrium toward TPQsq in an "on-copper" conformation, in which the 4-OH group ligated axially to the copper center, which was probably reduced to Cu(I). When the crystals were soaked with substrate in the presence of halide ions, which act as uncompetitive and noncompetitive inhibitors with respect to the amine substrate and dioxygen, respectively, the equilibrium in the crystals shifted toward the "off-copper" conformation of TPQamr. The halide ion was bound to the axial position of the copper center, thereby preventing TPQamr from adopting the on-copper conformation. Furthermore, transient kinetic analyses in the presence of viscogen (glycerol) revealed that only the rate constant in the step of TPQamr/TPQsq interconversion is markedly affected by the viscogen, which probably perturbs the conformational change. These findings unequivocally demonstrate that TPQ undergoes large conformational changes during the reductive half-reaction.

Crystal Structures of the L1, L2, N, and O States of pharaonis Halorhodopsin

Halorhodopsin from Natronomonas pharaonis (pHR) functions as a light-driven halide ion pump. In the presence of halide ions, the photochemical reaction of pHR is described by the scheme: K→ L1 → L2 → N → O → pHR′ → pHR. Here, we report light-induced structural changes of the pHR-bromide complex observed in the C2 crystal. In the L1-to-L2 transition, the bromide ion that initially exists in the extracellular vicinity of retinal moves across the retinal Schiff base. Upon the formation of the N state with a bromide ion bound to the cytoplasmic vicinity of the retinal Schiff base, the cytoplasmic half of helix F moves outward to create a water channel in the cytoplasmic interhelical space, whereas the extracellular half of helix C moves inward. During the transition from N to an N-like reaction state with retinal assuming the 13-cis/15-syn configuration, the translocated bromide ion is released into the cytoplasmic medium. Subsequently, helix F relaxes into its original conformation, generating the O state. Anion uptake from the extracellular side occurs when helix C relaxes into its original conformation. These structural data provide insight into the structural basis of unidirectional anion transport.

Base-free non-noble-metal-catalyzed hydrogen generation from formic acid: scope and mechanistic insights.

The iron-catalyzed dehydrogenation of formic acid has been studied both experimentally and mechanistically. The most active catalysts were generated in situ from cationic Fe(II) /Fe(III) precursors and tris[2-(diphenylphosphino)ethyl]phosphine (1, PP3 ). In contrast to most known noble-metal catalysts used for this transformation, no additional base was necessary. The activity of the iron catalyst depended highly on the solvent used, the presence of halide ions, the water content, and the ligand-to-metal ratio. The optimal catalytic performance was achieved by using [FeH(PP3 )]BF4 /PP3 in propylene carbonate in the presence of traces of water. With the exception of fluoride, the presence of halide ions in solution inhibited the catalytic activity. IR, Raman, UV/Vis, and EXAFS/XANES analyses gave detailed insights into the mechanism of hydrogen generation from formic acid at low temperature, supported by DFT calculations. In situ transmission FTIR measurements revealed the formation of an active iron formate species by the band observed at 1543 cm(-1) , which could be correlated with the evolution of gas. This active species was deactivated in the presence of chloride ions due to the formation of a chloro species (UV/Vis, Raman, IR, and XAS). In addition, XAS measurements demonstrated the importance of the solvent for the coordination of the PP3 ligand.

Acceleration of Electroless Silver Deposition from Solutions Containing Cobalt(II) as Reducing Agent

By using cobalt(II) complexes with ammonia or organic amines as reducing agents electroless silver plating solutions of high stability were developed; the deposition of high quality Ag layers with plating rate 1 – 3 μm/h are known [1-3].In this work, the possibilities to increase silver plating rate without changing of concentration of reactants and temperature were studied. The additives enhancing the partial electrochemical reactions of the electroless plating process – anodic Co(II) oxidation and cathodic Ag(I) reduction – were applied. The effect of chloride and bromide ions was studied by electrochemical and chemical kinetics methods, including electrochemical quartz crystal microgravimetry (EQCM).Electrochemical measurements showed that the Co(II) anodic oxidation on silver electrode is enhanced by the presence of halide ions. At 1 mM level, KCl additive change the rate of Co(II) oxidation only little, while KBr and KI increase the rate considerably. Accelerating effect of halides corresponds to the increase in adsorption ability of halides in the sequence Cl-<Br-<I-, the adsorbed halide ions could facilitate the electron transfer through the halide bridge. The electroless silver deposition was shown to increase by factor of 2-3 at chloride concentrations 20 – 50 mM at satisfactory solution stability. The enhancing effect is related to anodic cobalt(II) oxidation reaction. AFM images of the silver surface showed absence of considerable changes of real surface area, and the rate increase is obviously not caused by development of catalytic surface.

Роль оксида азота в эмбриогенезе кур с разным типом продуктивности

It is known that nitric oxide (NO) mediates the regulation of smooth muscle tone in the blood vessels and the gastrointestinal tract, the central and autonomic nervous systems activity, differentiation and apoptosis in tissues, immune response, and gene expression in animals and humans. This is a short-lived substance oxidized rapidly to nitrate and nitrite. Embryogenesis is associated with the synthesis of nitric oxide (NO) and accumulation of its metabolites in embryo. Nevertheless, the mechanism of this relationship is unknown. In this paper we reported the results of comparing dynamics of the NO metabolite levels in the parts of and a whole embryo in the layers and broiler chicks. Incubated eggs were examined in the breeds (Andalusian Blue, Yurlovskaya Golosistaya, Golubaya Myasoyaichnaya, Cochin White, Brahma Dark, Brahma Pale, P-11, Cornish, Plymouth Rock, Malay fighting hens, Uzbek fighting hens), some lines (Х1, Х2, Х12, Х34 of Hysex White cross, B5, B6 and B56 of Cornish, B7, B9, and B79 of Plymouth Rock), and four crosses (SP 789, Hysex White, Smena 8, Cobb 500). The NO metabolites were detected using developed enzymatic sensor. The test is based on catalase inhibition by nitrite, nitrosothiols (RSNO), Fe-dinitrosyl complex and nitro derivatives of high-molecular compounds (RNO 2) in the presence of halide ions, repressed by the factors different for each class of compounds. The close correlation was observed between meat productivity of adult poultry and NO metabolites accumulation in different embryo parts. The NO metabolite accumulation differed up to 100 times in meatand egg-hen embryos, and in meat-egg hens and mini-hens the intermediate parameters were indicated. It was shown that nitrate as a final metabolic product was accumulated in the muscle of embryo. Due to time when the most intensive accumulation occurs in ontogenesis (3 days), some factor rather than the muscle itself, but influencing muscle histogenesis could be considered as the main agent involved in NO metabolism. Nitric oxide as a mediator can either activate this agent, or affect its synthesis.

Computational Insights on the Geometrical Arrangements of Cu(II) with a Mixed-Donor N3S3 Macrobicyclic Ligand

The macrobicyclic mixed-donor N3S3 cage ligand AMME-N3S3sar (1-methyl-8-amino-3,13,16-trithia-6,10,19-triazabicyclo[6.6.6]eicosane) can form complexes with Cu(II) in which it acts as hexadentate (N3S3) or tetradentate (N2S2) donor. These two complexes are in equilibrium that is strongly influenced by the presence of halide ions (Br(-) and Cl(-)) and the nature of the solvent (DMSO, MeCN, and H2O). In the absence of halides the hexadentate coordination mode of the ligand is preferred and the encapsulated complex ("Cu-in(2+)") is formed. Addition of halide ions in organic solvents (DMSO or MeCN) leads to the tetradentate complex ("Cu-out(+)") in a polyphasic kinetic process, but no Cu-out(+) complex is formed when the reaction is performed in water. Here we applied density functional theory calculations to study the mechanism of this interconversion as well as to understand the changes in the reactivity associated with the presence of water. Calculations were performed at the B3LYP/(SDD,6-31G**) level, in combination with continuum (MeCN) or discrete-continuum (H2O) solvent models. Our results show that formation of Cu-out(+) in organic media is exergonic and involves sequential halide-catalyzed inversion of the configuration of a N-donor of the macrocycle, rapid halide coordination, and inversion of the configuration of a S-donor. In aqueous solution the solvent is found to have an effect on both the thermodynamics and the kinetics of the reaction. Thermodynamically, the process becomes endergonic mainly due to the preferential solvation of halide ions by water, while the kinetics is influenced by formation of a network of H-bonded water molecules that surrounds the complex.

Au@Ag Nanoparticles: Halides Stabilize {100} Facets

Seed-mediated growth is the most efficient methodology to control the size and shape of colloidal metal nanoparticles. In this process, the final nanocrystal shape is defined by the crystalline structure of the initial seed as well as by the presence of ligands and other additives that help to stabilize certain crystallographic facets. We analyze here the growth mechanism in aqueous solution of silver shells on presynthesized gold nanoparticles displaying various well-defined crystalline structures and morphologies. A thorough three-dimensional electron microscopy characterization of the morphology and internal structure of the resulting core–shell nanocrystals indicates that {100} facets are preferred for the outer silver shell, regardless of the morphology and crystallinity of the gold cores. These results are in agreement with theoretical analysis based on the relative surface energies of the exposed facets in the presence of halide ions.

Effect of halides ions on H2 production during aluminum corrosion in formic acid and using some inorganic inhibitors to control hydrogen evolution

This study reports on the systematic assessment of H2 production by corrosion of aluminum in formic acid solution in the absence and presence of halide ions and some inorganic inhibitors using hydrogen evolution measurements and complemented by scan electron microscope (SEM) and energy dispersive X-ray (EDX). It is shown that the rate of H2 production and in turn the dissolution of aluminum increases with increasing acid concentration and solution temperature. Addition of halides ions enhances the active dissolution of aluminum and tends to breakdown the passive film and increases H2 production. The addition of tungstate, molybdate and nitrite anions to (1.0 M formic acid + 0.2 M Cl−) solution retard the rate of H2 production, where the H2 production process decreases in the following in the order: tungstate > molybdate > nitrite.