Articles de revues : « Radicale CN »

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Makiabadi, Batoul, Mohammad Zakarianezhad et Shahin Mohammadzamani. « Theoretical Study of CN Radicals Chemisorption on the Electronic Properties of BC₂N Nanotube ». Journal of Nano Research 48 (juillet 2017) : 38–48. http://dx.doi.org/10.4028/www.scientific.net/jnanor.48.38.

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In this work, we have investigated the adsorption behavior of the CN radicals on electronic properties of BC2N nanotube (BC2NNT) by means of the B3LYP hybrid density functional method using 6-31G(d) basis set. The results show that CN radicals can be chemically adsorbed on the nanotube. Based on the energy analysis, the most stable position of CN radical on the nanotube is C1 site. Also, the C-side complexes are more stable than the N-side complexes. We investigated the effects of CN radicals adsorption on the electronic properties of the BC2N nanotube. According to our calculations, band gap energy of the BC2NNT decreases with increasing the number of CN radicals. It is predicted that the conductivity and reactivity of nanotube increase by increasing the number of CN radicals. Based on the NBO analysis, in all complexes charge transfer occurs from nanotube to CN radical. The AIM results show that, the Xtube…YCN interaction has covalent nature. Generally, The BC2N nanotube can be used to as sensor for nanodevice applications.

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Wang, Degui, Heinz-Peter Schuchmann et Clemens von Sonntag. « Phenylalanine : Its ˙OH and SO4˙⁻-Induced Oxidation and Decarboxylation. A Pulse Radiolysis and Product Analysis Study ». Zeitschrift für Naturforschung B 48, n^o 6 (1 juin 1993) : 761–70. http://dx.doi.org/10.1515/znb-1993-0610.

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Phenylamine has been oxidized by radiolytically generated hydroxyl and sulfate radicals, the ensuing intermediates and their reactions have been studied by pulse radiolysis and product analysis in the absence and presence of oxidants such as Fe(CN)63- and O2. Upon OH radical attack, hydroxycyclohexadienyl-type radicals are mainly formed while Η-abstraction reactions can be neglected. In the presence of Fe(CN)63- these radicals are for the most part oxidized to the corresponding tyrosines (80%), except for the ipso-OH-adduct radicals (≈ 20%). It is concluded that ˙OH-addition is almost random, but with a slight avoidance of the metaposition relative to the ortho-, para- and ipso-positions. Oxygen adds reversibly to the OH-adduct radicals (kf = 1.8 × 108 dm3 mol-1 s-1, kr = 5.4 × 104 s-1). In this case, tyrosine formation occurs by HO2˙-elimination. However, due to side reactions, tyrosine formation only reaches 52% of the OH radical yield. The tyrosine yield drops to 10% in the absence of an oxidant.Upon SO4˙⁻-attack, decarboxylation becomes a major process (33% of SO4˙⁻) alongside the production of tyrosines (43%). Here, with Fe(CN)63- as the oxidant the formation of p-Tyr (18.5%) and m-Tyr (16.5%) is preferred over o-Tyr formation (8.5%). It is believed that in analogy to other systems a radical cation is formed immediately upon SO4˙⁻-attack which either reacts with water under the formation of hydroxycyclohexadienyl-type (“OH-adduct”) radicals, or decarboxylates after intramolecular electron transfer. The radical cation can also arise indirectly through H+-catalysed water elimination from the ˙OH-adduct radicals. At pH 2 and a dose rate of 0.0046 Gy s-1 CO2 formation matches the OH radical yield when ˙OH is the attacking radical. Below pH 2, G(CO2) decreases with falling pH. This indicates the occurrence of another, unimolecular, pathway under these conditions competing effectively with decarboxylation. This appears to be a relatively slow deprotonation reaction of the carboxylprotonated phenylalanine radical cation which gives rise to the benzyl-type radical.

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Hänni, Nora, Kathrin Altwegg, Boris Pestoni, Martin Rubin, Isaac Schroeder, Markus Schuhmann et Susanne Wampfler. « First in situ detection of the CN radical in comets and evidence for a distributed source ». Monthly Notices of the Royal Astronomical Society 498, n^o 2 (3 septembre 2020) : 2239–48. http://dx.doi.org/10.1093/mnras/staa2387.

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ABSTRACT Although the debate regarding the origin of the cyano (CN) radical in comets has been ongoing for many decades, it has yielded no definitive answer to date. CN could previously only be studied remotely, strongly hampering efforts to constrain its origin because of very limited spatial information. Thanks to the European Space Agency's Rosetta spacecraft, which orbited comet 67P/Churyumov–Gerasimenko for 2 yr, we can investigate, for the first time, CN around a comet at high spatial and temporal resolution. On board Rosetta's orbiter module, the high-resolution double-focusing mass spectrometer DFMS, part of the ROSINA instrument suite, analysed the neutral volatiles (including HCN and the CN radical) in the inner coma of the comet throughout that whole 2-yr phase and at variable cometocentric distances. From a thorough analysis of the full-mission data, the abundance of CN radicals in the cometary coma has been derived. Data from a close flyby event in 2015 February indicate a distributed origin for the CN radical in comet 67P/Churyumov–Gerasimenko.

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Cordes, A. Wallace, Charles M. Chamchoumis, Robin G. Hicks, Richard T. Oakley, Kelly M. Young et Robert C. Haddon. « Mono- and difunctional furan-based 1,2,3,5-dithiadiazolyl radicals ; preparation and solid state structures of 2,5-[(S2N2C)OC4H2(CN2S2)] and 2,5-[(S2N2C)OC4H2(CN)] ». Canadian Journal of Chemistry 70, n^o 3 (1 mars 1992) : 919–25. http://dx.doi.org/10.1139/v92-123.

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The preparation and solid state characterization of the bifunctional radical furan-2,5-bis(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN2S2)] and the related monofunctional radical 2-cyanofuran-5-(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN)] are described. The crystal structure of 2,5-[(S2N2C)OC4H2(CN2S2)] is orthorhombic, space group Pna21, and consists of interleaved arrays of dimers, for which the mean interannular [Formula: see text] contact is 3.137 Å. The crystal structure of the monofunctional radical 2,5-[(S2N2C)OC4H2(CN)] is monoclinic, space group P21/n, and consists of a ribbon-like network of dimers (mean interannular [Formula: see text] interconnected by close head-to-tail [Formula: see text] contacts. The dimer units form stacks parallel to z, with a mean interdimer [Formula: see text] separation of 3.956 Å. The similarities and differences between these two crystal structures and those of related benzene-substituted systems are discussed. Keywords: dithiadiazolyl radicals, furan-based diradicals, cyanofuran-based radicals, radical dimers, crystal structures.

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Xu, Jun, Tengcai Ma, Jialiang Zhang, Xinlu Deng, Wenfang Zhang et Alessio Perrone. « INVESTIGATION ON OPTICAL EMISSION SPECTRA DURING ECR PLASMA ENHANCED MAGNETRON SPUTTERING CARBON NITRIDE FILM DEPOSITION ». International Journal of Modern Physics B 16, n^o 06n07 (20 mars 2002) : 1120–26. http://dx.doi.org/10.1142/s021797920201097x.

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Emission spectra from the ECR plasma enhanced magnetron sputtering discharge used for CNx film deposition were investigated in the wavelength range 350 – 550 nm. The optical emission spectra from both the negative glow discharge zone near the target surface and the plasma zone formed by ECR discharge and magnetron discharge were studied separately. The dominant chemical species in both zone were found to be N2+, N2* , and CN radicals. But the intensity of CN radical in the plasma zone was greater than that in the negative zone, where an emission band of C2 was detected. The dependence of the intensities of CN band on the working gas pressure was investigated, and the formation of CN radicals, which could be vital in the CNx film deposition process, was discussed. It was shown that a possible mechanism could be the reaction of N2+ and N 2 with C 2 in the gas phase.

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Das, Suresh, et Clemens von Sonntag. « The Oxidation of Trimethylamine by OH Radicals in Aqueous Solution, as Studied by Pulse Radiolysis, ESR, and Product Analysis. The Reactions of the Alkylamine Radical Cation, the Aminoalkyl Radical, and the Protonated Aminoalkyl Radical ». Zeitschrift für Naturforschung B 41, n^o 4 (1 avril 1986) : 505–13. http://dx.doi.org/10.1515/znb-1986-0418.

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Hydroxyl radical reactions with trimethylamine in aqueous solution lead to the formation of the aminoalkyl radical (CH3)2NCH2 (A) and its conjugated acid (CH3)2HN+CH2 (AH+) as well as to the alkylamine radical cation (CH3)3N+(N+). These radicals are transform ed into each other by hydrolytic reactions, e.g.[xxx]Radicals AH+ are more acidic (pKa ≈ 3.6) than the radicals N+(pKa ≈ 8.0). Consequently, N+ predom inate over AH+ under quasi equilibrium conditions (e.g. in the presence of phosphate buffer) and are the only species observed by ESR in acid solutions. Reacting with the protonated amine. OH radicals abstract hydrogen at nitrogen and at carbon with comparable ease. Reaction of OH radicals with the free amine may initially also generate N+, beside H-abstraction at carbon. Radicals A’ absorb more strongly at 260 nm (ε = 3390 dm3mol-1cm-1) than the radical cation N+(ε = 950 dm3mol-1cm-1). Radical A' has reducing properties whereas radicals AH+ and N+ have oxidizing properties and hence can be monitored with p-nitroacetophenone (the reducing radicals), and Fe(CN)64- , N ,N'-tetramethyl-p-phenylenediamine and 2,2'-azinobis-(3-ethyl-benzthiazoline- 6-sulphonate) (the oxidizing radicals). These radicals mainly (≥ 85 % ) disproportionate. one of the products being formaldehyde

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Yong, Yoke Keong, Jun Jie Tan, Soek Sin Teh, Siau Hui Mah, Gwendoline Cheng Lian Ee, Hoe Siong Chiong et Zuraini Ahmad. « Clinacanthus nutansExtracts Are Antioxidant with Antiproliferative Effect on Cultured Human Cancer Cell Lines ». Evidence-Based Complementary and Alternative Medicine 2013 (2013) : 1–8. http://dx.doi.org/10.1155/2013/462751.

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Clinacanthus nutansLindau leaves (CN) have been used in traditional medicine but the therapeutic potential has not been explored for cancer prevention and treatment. Current study aimed to evaluate the antioxidant and antiproliferative effects of CN, extracted in chloroform, methanol, and water, on cancer cell lines. Antioxidant properties of CN were evaluated using DPPH, galvinoxyl, nitric oxide, and hydrogen peroxide based radical scavenging assays, whereas the tumoricidal effect was tested on HepG2, IMR32, NCL-H23, SNU-1, Hela, LS-174T, K562, Raji, and IMR32 cancer cells using MTT assay. Our data showed that CN in chloroform extract was a good antioxidant against DPPH and galvinoxyl radicals, but less effective in negating nitric oxide and hydrogen peroxide radicals. Chloroform extract exerted the highest antiproliferative effect on K-562 (91.28±0.03%) and Raji cell lines (88.97±1.07%) at 100 μg/ml and the other five cancer cell lines in a concentration-dependent manner, but not on IMR-32 cells. Fourteen known compounds were identified in chloroform extract, which was analysed by gas chromatography—mass spectra analysis. In conclusion, CN extracts possess antioxidant and antiproliferative properties against cultured cancer cell lines, suggesting an alternate adjunctive regimen for cancer prevention or treatment.

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McNavage, William, William Dailey et Hai-Lung Dai. « The ν1 and ν2 vibrational bands of the OCCN radical detected through time-resolved Fourier transform IR emission spectroscopy ». Canadian Journal of Chemistry 82, n^o 6 (1 juin 2004) : 925–33. http://dx.doi.org/10.1139/v04-041.

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Through monitoring the IR emission from vibrationally excited radicals generated by exothermic photolysis reactions, the CN stretch (ν1) and the CO stretch (ν2) vibrational bands of the cyanooxomethyl radical (OCCN) have been observed for the first time at 2093 cm1 and 1774 cm1, respectively. The OCCN radical was produced through 193 nm photolysis of methyl cyanoformate (NCC(O)OCH3), carbonyl cyanide (NCC(O)CN), and pivaloyl cyanide (NCC(O)C(CH3)3). The IR emission spectra were recorded by using nanosecond time-resolved Fourier transform IR emission spectroscopy. Assignments of the spectral peaks were made based on observed time and pressure dependences of IR emission intensities, ab initio calculations, and two-dimensional cross-spectra correlation analysis. Key words: radical, cyanooxomethyl, OCCN, time-resolved vibrational spectroscopy, FTIR, substituted carbonyl dissociation reactions, two-dimensional cross-spectra correlation analysis

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Mieden, Oliver J., et Clemens von Sonntag. « Peptide Free-Radicals : The Reactions of OH Radicals with Glycine Anhydride and its Methyl Derivatives Sarcosine and Alanine Anhydride. A Pulse Radiolysis and Product Study ». Zeitschrift für Naturforschung B 44, n^o 8 (1 août 1989) : 959–74. http://dx.doi.org/10.1515/znb-1989-0818.

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The reactions of radiolytically generated OH radicals and H atoms with the cyclic dipeptides of glycine, alanine and sarcosine in deoxygenated aqueous solutions and the subsequent reactions of the transient peptide radicals were studied in the absence and presence of K3Fe(CN)6 as oxidant by pulse radiolysis and product analysis.Hydroxyl radicals and H atoms react with glycine anhydride and alanine anhydride by abstracting an H atom bound at C-3; there is no evidence for any other site of attack at these two peptides. The resulting radicals have pKa values of 9.8 and 10.6, respectively.In the absence of an oxidant the radicals decay by second order (2k = 7.0×108 dm3 mol-1 s-1 and 2k = 4.4×108 dm3 mol-1 s-1, resp.), the main fraction (94% of the glycine anhydride-derived radicals, 90% of the alanine anhydride-derived radicals) yielding dehydrodimers (G = 0.58 μmol J-1 and 0.56 µmol J-1 (in monomer units), resp.). A small portion however disproportionates via abstraction of a C-6-bound Η atom followed by isomerization to 2,5-dihydroxypyrazines (pKa values of the parent 2,5-dihydroxypyrazine at about 7.9 and 10.1) and subsequent addition of water to 2,5-diketo-3-hydroxypiperazines, thus indicating that the transfer of a carbon-bound hydrogen atom is prefered to the transfer of a nitrogen-bound hydrogen atom.No disproportionation products but three different dehydrodimers (G = 0.36, 0.18 and 0.04 µmol J-1 (in monomer units)) were found after irradiation of sarcosine anhydride. In this case a dose rate and solute concentration dependence of dehydrodimer formation indicates a radical-solute reaction converting part of the N-methyl radicals (21% of ‘initial’ attack) into the C-3-yl radicals. A rate constant of k = 600 ± 50 dm3 mol-1 s-1 was obtained for this reaction by measuring and computing the dehydrodimer yields as a function of dose rate and solute concentration. Thus the observed transient spectrum accounts only for about 79% of the radicals from the ‘initial’ attack at C-3.The rate of oxidation of the glycine anhydride-derived radicals by Fe(CN)63- reflects the pKa of the transient radical. The rate constant for oxidation of the (protonated) radical derived from glycine anhydride is: k = 1.0x 108 dm3 mol-1, the corresponding radical anion is oxidized with k = 3.1 × 108 dm3 mol-1 s-1. No change with pH was observed in the case of the alanine anhydridederived radicals (k = 7.9x 108 dm3 mol-1 s-1). In contrast to the disproportionation, oxidation by Fe(CN)63- leads to the removal of a proton from the heteroatom, a carbocation being the intermediate. The resulting dehydropiperazines rapidly add water to yield the corresponding 2,5-diketo-3-hydroxypiperazines (G = 0.61 μmol J-1 after oxidation of the glycine anhydride-derived radicals, G = 0.58 µmol J-1 after oxidation of the alanine anhydride-derived radicals). The radicals derived from sarcosine anhydride are readily oxidized with k = 4.0×108 dm3 mol-1 s-1, independent of pH.1H and 13C{1H} NMR-spectroscopic and mass-spectroscopic data of the products are given.

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Liu, Dongping, Ina T. Martin, Jie Zhou et Ellen R. Fisher. « Radical-surface interactions during film deposition : A sticky situation ? » Pure and Applied Chemistry 78, n^o 6 (1 janvier 2006) : 1187–202. http://dx.doi.org/10.1351/pac200678061187.

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Our imaging of radicals interacting with surfaces (IRIS) method was used to investigate radical-surface reactions during low-temperature plasma-enhanced chemical vapor deposition (PECVD) processes. Special emphasis was placed on the analysis of surface reactivities for CH, SiH, CN, NH, NH2, CF2, and SiCl2 radicals during film growth. The effects of plasma parameters, such as radio frequency (rf) power and gas composition, substrate temperature, and substrate bias on radical-surface reactivity were analyzed. Different radicals exhibit different behavior at the surface of a depositing film. Specifically, CH, SiH, and CN are "sticky", with high surface reactivities. In contrast, other species such as NH, CF2, and SiCl2 do not stick to the surface of growing films and, in some cases are actually generated at the surface of the depositing film. Different plasma systems and parameters can have an effect on the stickiness of some of these species. Our IRIS measurements indicate a molecule's surface sticking probability may also be related to the molecule's electronic configuration and stability, with the most reactive species being molecules with a doublet electron configuration. In contrast, the singlet species examined here tend to be generated at the surface during film deposition. Our results also indicate that when a molecule scatters with greater than 100 % probability, it is likely to be strongly affected by energetic ion bombardment of the film surface.

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Qubbaj, Ala R., et S. R. Gollahalli. « Laser-Induced Fluorescence Measurements in Venturi-Cascaded Propane Gas Jet Flames ». Journal of Energy Resources Technology 123, n^o 2 (10 novembre 2000) : 158–66. http://dx.doi.org/10.1115/1.1368120.

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Venturi-cascading is a technique to control pollutant emissions from diffusion flames by modifying air infusion and fuel-air mixing rates through changing the flow dynamics in the combustion zone with a set of venturis surrounding the flame. A propane jet diffusion flame at a burner-exit Reynolds number of 5100 was examined with a set of venturis of specific sizes and spacing arrangement. The venturi-cascading technique resulted in a decrease of 33 percent in NO emission index along with a 24-percent decrease in soot emission from the flame, compared to the baseline condition (same flame without venturis). In order to understand the mechanism behind these results, laser-induced fluorescence (LIF) spectroscopy was employed to study the concentration field of the radicals (OH, CH, and CN) in the baseline and venturi-cascaded flames. The LIF measurements, in the near-burner region of the venturi-cascaded flame, indicated an average decrease of 18, 24 and 12 percent in the concentrations of OH, CH, and CN radicals, respectively, from their baseline values. However, in the midflame region, a 40-percent average increase in OH from its baseline value was observed. In this region, CH or CN radicals were not detected. The OH radical concentration in the downstream locations was mostly affected by soot rather than by temperature.

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Manoj, Kelath Murali, Surjith Ramasamy, Abhinav Parashar, Daniel Andrew Gideon, Vidhu Soman, Vivian David Jacob et Kannan Pakshirajan. « Acute toxicity of cyanide in aerobic respiration : Theoretical and experimental support for murburn explanation ». Biomolecular Concepts 11, n^o 1 (17 mars 2020) : 32–56. http://dx.doi.org/10.1515/bmc-2020-0004.

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AbstractThe inefficiency of cyanide/HCN (CN) binding with heme proteins (under physiological regimes) is demonstrated with an assessment of thermodynamics, kinetics, and inhibition constants. The acute onset of toxicity and CN’s mg/Kg LD50 (μM lethal concentration) suggests that the classical hemeFe binding-based inhibition rationale is untenable to account for the toxicity of CN. In vitro mechanistic probing of CN-mediated inhibition of hemeFe reductionist systems was explored as a murburn model for mitochondrial oxidative phosphorylation (mOxPhos). The effect of CN in haloperoxidase catalyzed chlorine moiety transfer to small organics was considered as an analogous probe for phosphate group transfer in mOxPhos. Similarly, inclusion of CN in peroxidase-catalase mediated one-electron oxidation of small organics was used to explore electron transfer outcomes in mOxPhos, leading to water formation. The free energy correlations from a Hammett study and IC50/Hill slopes analyses and comparison with ligands $\left( {\text{CO}}/{{{{\text{H}}_{2}}\text{S}}/{\text{N}_{3}^{\text{-}}}\;}\; \right)$ provide insights into the involvement of diffusible radicals and proton-equilibriums, explaining analogous outcomes in mOxPhos chemistry. Further, we demonstrate that superoxide (diffusible reactive oxygen species, DROS) enables in vitro ATP synthesis from ADP+phosphate, and show that this reaction is inhibited by CN. Therefore, practically instantaneous CN ion-radical interactions with DROS in matrix catalytically disrupt mOxPhos, explaining the acute lethal effect of CN.

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Milašinović, Valentina, Krešimir Molčanov, Anna Krawczuk, Nikita E. Bogdanov, Boris A. Zakharov, Elena V. Boldyreva, Christian Jelsch et Biserka Kojić-Prodić. « Charge density studies of multicentre two-electron bonding of an anion radical at non-ambient temperature and pressure ». IUCrJ 8, n^o 4 (12 juin 2021) : 644–54. http://dx.doi.org/10.1107/s2052252521005273.

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The variation of charge density of two-electron multicentre bonding (pancake bonding) between semiquinone radicals with pressure and temperature was studied on a salt of 5,6-dichloro-2,3-dicyanosemiquinone radical anion (DDQ) with 4-cyano-N-methylpyridinium cation (4-CN) using the Transferable Aspheric Atom Model (TAAM) refinement. The pancake-bonded radical dimers are stacked by non-bonding π-interactions. With rising pressure, the covalent character of interactions between radicals increases, and above 2.55 GPa, the electron density indicates multicentric covalent interactions throughout the stack. The experimental charge densities were verified and corroborated by periodic DFT computations. The TAAM approach has been tested and validated for atomic resolution data measured at ambient pressure; this work shows this approach can also be applied to diffraction data obtained at pressures up to several gigapascals.

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Sun, Jiayue, Lianying Wang, Simei Lu, Zhuoyuan Wang, Menglin Chen, Weixia Liang, Xiu Lin et Xiangfeng Lin. « Environmentally Friendly g-C3N4/Sepiolite Fiber for Enhanced Degradation of Dye under Visible Light ». Molecules 27, n^o 8 (11 avril 2022) : 2464. http://dx.doi.org/10.3390/molecules27082464.

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Herein, novel visible light active graphitic carbon nitride (g-C3N4)/sepiolite fiber (CN/SS) composites were fabricated via a facile calcination route, exploiting melamine and thiourea as precursors, and sepiolite fiber as support, for efficient degradation of organic dye methylene blue (MB). The as-prepared CN/SS composites were characterized by various characterization techniques based on structural and microstructural analyses. The effects of CN loading amount, catalyst dosage and initial concentration of dye on the removal rate of dye under visible light were systematically studied. The removal rate of MB was as high as 99.5%, 99.6% and 99.6% over the composites when the CN loading amount, catalyst dosage and initial concentration of dye were 20% (mass percent), 0.1 g, and 15 mg/L in 120 min, respectively. The active species scavenging experiments and electron paramagnetic resonance (EPR) measurement indicated that the holes (h+), hydroxyl radical (·OH) and superoxide radicals (·O2−) were the main active species. This study provides for the design of low-cost, environmentally friendly and highly efficient catalysts for the removal of organic dye.

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Li, Chunmin, Changjie Kan, Xiangtai Meng, Mengxue Liu, Qianqian Shang, Yikai Yang, Yu Wang et Xiaoxue Cui. « Self−Assembly 2D Ti3C2/g−C3N4 MXene Heterojunction for Highly Efficient Photocatalytic Degradation of Tetracycline in Visible Wavelength Range ». Nanomaterials 12, n^o 22 (15 novembre 2022) : 4015. http://dx.doi.org/10.3390/nano12224015.

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An ultrathin 2D Ti3C2/g−C3N4 MXene (2D−TC/CN) heterojunction was synthesized, using a facile self−assembly method; the perfect microscopic−morphology and the lattice structure presented in the sample with a 2 wt% content of Ti3C2 were observed by the field−emission scanning electron microscopy (SEM) and transmission electron microscope (TEM). The optimized sample (2−TC/CN) exhibited excellent performance in degrading the tetracycline (TC), and the degradation rate reached 93.93% in the conditions of 20 mg/L, 50 mL of tetracycline within 60 min. Except for the increased specific−surface area, investigated by UV−vis diffuse reflectance spectra (UV−vis DRS) and X−ray photoelectron microscopy (XPS) valence spectra, the significantly enhanced photocatalytic activity of the 2−TC/CN could also be ascribed to the formation of Ti−N bonds between Ti3C2 and g−C3N4 nanosheets, which reduced the width of the band gap through adjusting the position of the valence band, thus resulting in the broadened light−absorption. Furthermore, the facilitated electron transmission was also proved by time−resolved photoluminescence (TRPL) and electrochemical impedance spectroscopy (EIS), which is effective in improving the quantum efficiency of photo−generated electrons. In addition, the resulting radical−capture experiment suggested that superoxide radicals have the greatest influence on photodegradation performance, with the photodegradation rate of TC reducing from 93.16% to 32.08% after the capture of superoxide radicals, which can be attributed to the production of superoxide radicals only, by the 2−TC/CN composites with a high conduction−band value (−0.62 eV). These facilely designed 2D Ti3C2/g−C3N4 composites possess great application potential for the photodegradation of tetracycline and other antibiotics.

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Puzzarini, Cristina, Zoi Salta, Nicola Tasinato, Jacopo Lupi, Carlo Cavallotti et Vincenzo Barone. « A twist on the reaction of the CN radical with methylamine in the interstellar medium : new hints from a state-of-the-art quantum-chemical study ». Monthly Notices of the Royal Astronomical Society 496, n^o 4 (16 juin 2020) : 4298–310. http://dx.doi.org/10.1093/mnras/staa1652.

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ABSTRACT Despite the fact that the majority of current models assume that interstellar complex organic molecules (iCOMs) are formed on dust–grain surfaces, there is some evidence that neutral gas-phase reactions play an important role. In this paper, we investigate the reaction occurring in the gas phase between methylamine (CH3NH2) and the cyano (CN) radical, for which only fragmentary and/or inaccurate results have been reported to date. This case study allows us to point out the pivotal importance of employing quantum-chemical calculations at the state of the art. Since the two major products of the CH3NH2 + CN reaction, namely the CH3NH and CH2NH2 radicals, have not been spectroscopically characterized yet, some effort has been made for filling this gap.

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Nishimura, N., K. Takeda et Y. Furumatsu. « E.S.R. and Kinetic Studies on Radicals Produced by Photolysis of Bis(1-methylethyl)diazenes (Azoisopropanes) ». Australian Journal of Chemistry 42, n^o 6 (1989) : 823. http://dx.doi.org/10.1071/ch9890823.

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Radicals generated by photolysis of bis(1-methylethyl) diazenes (azoisopropanes) Me2C(X)-N=N-C(X)Me2, where X = -CN, -SCN, -SPh and -OAc, have been studied by means of spin trapping and radical scavenger techniques. The primarily photoproduced radicals of the type C(X)Me2 were trapped by N-t-butyl-a- phenylnitrone, except for X = -SCN. In this case, thiocyanatyl radicals were trapped by N-t-butyl-a- phenylnitrone . Radicals generated by thermoiysis were all of the type 'C(X)Me2. The diffusive separation process of a pair of photoproduced geminate radicals was investigated spectrophotometrically by following the disappearance of 2,4,6-triphenyl-3,4-dihydro-1,2,4,5-tetrazin-12H)-yl ( verdazyl ), in binary solvent systems of different viscosities. The reciprocal of the apparent zero-order rate constant with respect to verdazyl was found to be linearly related to the viscosity. This first-power relationship is briefly considered.

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Ito, Haruhiko, Hitoshi Araki et Akira Wada. « Sticking probability of CN radicals ». Diamond and Related Materials 20, n^o 3 (mars 2011) : 355–58. http://dx.doi.org/10.1016/j.diamond.2011.01.030.

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Nichols, PJ, et MW Grant. « The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes ». Australian Journal of Chemistry 42, n^o 7 (1989) : 1085. http://dx.doi.org/10.1071/ch9891085.

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The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by {Fe(CN)6}3- and 11 other substitution inert metal complexes have been investigated. Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step. A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple. For diethyldithiocarbamate, E �(edtc/edtc-) = 425 � 33 mV v.s.c.e. and the outer-sphere electron self-exchange rate constant is log kex = 7.0 � 0.3. A comparison with thiophenolate oxidation is also given.

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Kurokawa, Masashi, Judy Fe F. Jose-Larong, Hiroyuki Hasegawa, Yukihiro Takahashi, Jun Harada et Tamotsu Inabe. « Structural and transport properties of neutral radical crystals of CoIII(tmp)(CN)2 (tmp = 5,10,15,20-tetramethylporphyrinato) and the CN-bridged polymer [CoIII(tmp)(CN)]n ». Dalton Transactions 46, n^o 13 (2017) : 4422–29. http://dx.doi.org/10.1039/c6dt04418b.

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Rapoport, Abrão, Daniel Kanabben Ortellado, Ali Amar, Carlos Neutzling Lehn, Rogério Aparecido Dedivitis, Ricardo Salinas Perez et Helen Mara Rodrigues. « Esvaziamento radical versus seletivo (supraomohióideo) no tratamento do carcinoma epidermóide do andar inferior da boca ». Revista Brasileira de Otorrinolaringologia 73, n^o 5 (octobre 2007) : 641–46. http://dx.doi.org/10.1590/s0034-72992007000500009.

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O paradigma terapêutico para o CEC do andar inferior da boca sofreu modificações em decorrência da sobrevida. OBJETIVO: Estudo comparativo do esvaziamento cervical radical e seletivo. MATERIAL E MÉTODO: Análise de 460 pacientes atendidos no Depto. de CCP e ORL do Hospital Heliópolis, de 1978 a 2002. Para esvaziamento radical foram avaliados os padrões de metastatização dos níveis IV e V, para o seletivo a ocorrência e localização das recidivas. O método estatístico utilizado foi o teste do qui-quadrado. RESULTADOS: Nos esvaziamentos radicais a taxa de metastatização nos níveis IV e V foram 5,8% e 4,6%, nos pacientes cNO e de 9,9% (nível IV) e 5,9% (nível V) para cN+, enquanto o nível I isolado estava comprometido em 11,0% nos cN0 e 5,5% nos cN+. Nos esvaziamentos seletivos ocorreram 4 recidivas (4,1%) em 97 esvaziamentos nos pN0 e 2 (10,0%) em 20 esvaziamentos. Nos casos pN+, não houve vantagens na indicação de radioterapia sobre os não irradiados (5,6% e 5,7% respectivamente). CONCLUSÃO: É possível realizar esvaziamento seletivo no tratamento das metástases do andar inferior de boca.

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Higuchi, T. T., R. H. Breau, E. C. Umbreit, E. J. Bergstralh, L. J. Rangel, R. Carlson et R. J. Karnes. « Outcomes of patients with clinical lymphadenopathy treated with radical prostatectomy. » Journal of Clinical Oncology 29, n^o 7_suppl (1 mars 2011) : 106. http://dx.doi.org/10.1200/jco.2011.29.7_suppl.106.

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106 Background: Some patients with lymph node metastases experience prolonged survival following radical prostatectomy. The purpose of this study was to determine the outcome of patients with clinically suspicious lymph nodes on preoperative imaging who underwent radical prostatectomy and lymphadenectomy. Methods: Patients with lymph node metastases diagnosed during radical prostatectomy from 1988-2003 were reviewed. Patients with preoperative CT or MRI images were included in the study. Radiology reports were reviewed to determine if patients had clinically suspicious lymphadenopathy (cN+). For all analyses, patients with cN+ were compared to those with clinically negative nodes (cN−). Results: Preoperative imaging was available in 202 men with lymph node metastasis at the time of prostatectomy. Of these 17% (34/202) were cN+. None had pre-operative lymph node biopsy and none had abandoned prostatectomy. At a median follow-up of 11.1 years, PSA recurrence occurred in 50% (17/34) and 49% (82/186), local recurrence in 18% (6/34) and 13% (22/186) and systemic progression in 32% (11/34) and 24% (40/186) of patients with cN+ and cN-, respectively. On multivariate analysis, cN+ was not associated with increased risk of death (HR 1.66, p=0.1). Conclusions: cN+ patients undergoing surgical therapy for prostate cancer may experience similar outcomes to cN− patients. The presence of clinically suspicious lymph nodes on preoperative imaging should not be an absolute contraindication for surgical therapy. No significant financial relationships to disclose.

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Pérez-Molina, Álvaro, Luisa M. Pastrana-Martínez, Lorena T. Pérez-Poyatos, Sergio Morales-Torres et Francisco J. Maldonado-Hódar. « One-Pot Thermal Synthesis of g-C3N4/ZnO Composites for the Degradation of 5-Fluoruracil Cytostatic Drug under UV-LED Irradiation ». Nanomaterials 12, n^o 3 (21 janvier 2022) : 340. http://dx.doi.org/10.3390/nano12030340.

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Graphitic carbon nitride (g-C3N4) was used to enhance the photocatalytic activity of ZnO nanoparticles for the degradation of 5-fluorouracil (5-FU) cytostatic drug under UV-LED irradiation. CN/ZnO composites were synthetized by an easy one-pot thermal method, varying the g-C3N4 loading, i.e., from 10 to 67 wt% and a post-thermal exfoliation in air. The physicochemical and optical properties of the materials were analyzed by several techniques. CN/ZnO composites showed a coral-like structure of spherical ZnO wurtzite particles on the g-C3N4 structure. In general, the synergism and heterojunction interface between both phases allowed the enhancement of the mesoporosity, light absorption ability, and the aromaticity of the corresponding composites. Moreover, the photocatalytic activity of the CN/ZnO composites was increased with the addition of g-C3N4 in comparison with pristine ZnO. The highest activity was found for the composite containing 25 wt% of g-C3N4 (i.e., CN25/ZnO), reaching the total degradation of 5-FU and a mineralization of 48% at 180 min, as well as a good photostability during four reuse cycles. Experiments with different pH solutions and scavengers allowed for the assessment of the reactive oxygen species (ROS) involved in the 5-FU degradation pathway, with radicals and non-radical species as the main responsible active species. Furthermore, a tentative photocatalytic mechanism was proposed for CN/ZnO composites.

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Bock, Hans, et Ralph Dammel. « Photoelektronen-Spektren und Moleküleigenschaften, 110 [1,2] Tricyanmethan-Derivate X—C(CN)3 / Photoelectron Spectra and Molecular Properties, 110 [1, 2] Tricyanomethane Derivatives X-C(CN)3 ». Zeitschrift für Naturforschung B 42, n^o 3 (1 mars 1987) : 315–22. http://dx.doi.org/10.1515/znb-1987-0311.

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The photoelectron spectra of tricyanomethane derivatives X-C(CN)3 with substituents X = H, CH3, Br and C6H5 have been recorded and are assigned based on MNDO calculations as well as on radical cation state comparison with the iso(valence)electronic P(CN)3, within the series of cyanomethanes H4-nC(CN)n, and with each other. For HC(CN)3, no traces of the isomeric dicyano, ketimine HN = C=C(CN)2 are detected in the gas phase. Tricyanomethylbenzene, H5C6-C(CN)3, exhibiting the highest first ionization energy of any known singly acceptor substituted phenyl derivative, demonstrates the tremendous electron withdrawing effect of the -C(CN)3 group

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Yao, Hongjun, Wenfei Hu et Wei Zhang. « Difunctionalization of Alkenes and Alkynes via Intermolecular Radical and Nucleophilic Additions ». Molecules 26, n^o 1 (28 décembre 2020) : 105. http://dx.doi.org/10.3390/molecules26010105.

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Popular and readily available alkenes and alkynes are good substrates for the preparation of functionalized molecules through radical and/or ionic addition reactions. Difunctionalization is a topic of current interest due to its high efficiency, substrate versatility, and operational simplicity. Presented in this article are radical addition followed by oxidation and nucleophilic addition reactions for difunctionalization of alkenes or alkynes. The difunctionalization could be accomplished through 1,2-addition (vicinal) and 1,n-addition (distal or remote) if H-atom or group-transfer is involved in the reaction process. A wide range of moieties, such as alkyl (R), perfluoroalkyl (Rf), aryl (Ar), hydroxy (OH), alkoxy (OR), acetatic (O2CR), halogenic (X), amino (NR2), azido (N3), cyano (CN), as well as sulfur- and phosphorous-containing groups can be incorporated through the difunctionalization reactions. Radicals generated from peroxides or single electron transfer (SET) agents, under photoredox or electrochemical reactions are employed for the reactions.

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Khalil, Salim M. « A Theoretical Study of Fulvene Radical Cations ». Zeitschrift für Naturforschung A 43, n^o 5 (1 mai 1988) : 485–93. http://dx.doi.org/10.1515/zna-1988-0514.

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MINDO-Forces calculations have been performed, after complete optimization of geometry, on fulvene molecule, fulvene and X-fulvene radical cations, where X is OH, NH2, CH3, NO2, CN and F. A twisted structure with angle 5° was found for fulvene radical cation. The substituents OH, NH2, CH3, CN and F are stabilizing. NO2 is slightly stabilizing. Geometrical parameters, heats of formation, dipole moments and electron densities are reported.

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Matimba, Henri E. K., Astrid M. Crabbendam, Steen Ingemann et Nico M. M. Nibbering. « The gas-phase acidity of the phenyl radical and some C6H4X·(X = F, Cl, CN) radicals ». J. Chem. Soc., Chem. Commun., n^o 9 (1991) : 644–45. http://dx.doi.org/10.1039/c39910000644.

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Kaiser, Ralf I., et Nadia Balucani. « Astrobiology – the final frontier in chemical reaction dynamics ». International Journal of Astrobiology 1, n^o 1 (janvier 2002) : 15–23. http://dx.doi.org/10.1017/s1473550402001015.

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Crossed-beam experiments on the reactions of cyano CN(X2Σ+) and ethinyl C2H(X2Σ+) radicals with the unsaturated hydrocarbons acetylene, ethylene, methylacetylene allene and benzene have been carried out under single-collision conditions to investigate synthetic routes to form nitriles, polyynes and substituted allenes in hydrocarbon-rich atmospheres of planets and their moons. All reactions were found to proceed without an entrance barrier, to have exit barriers well below the energy of the reactant molecules and to be strongly exothermic. The predominant identification of the radical versus atomic hydrogen exchange channel makes these reactions compelling candidates for the formation of complex organic chemicals – precursors to biologically important amino acids – in Solar system environments and in the interstellar medium.

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Halpern, J. B., G. E. Miller et H. Okabe. « The reaction of CN radicals with cyanoacetylene ». Chemical Physics Letters 155, n^o 4-5 (mars 1989) : 347–50. http://dx.doi.org/10.1016/0009-2614(89)87167-2.

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Lavendy, H., J. M. Robbe et G. Gandara. « Theoretical photodissociation probability of the CN radical ». Journal of Physics B : Atomic and Molecular Physics 20, n^o 13 (14 juillet 1987) : 3067–74. http://dx.doi.org/10.1088/0022-3700/20/13/018.

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Li, Peng, et Wai Yip Fan. « The CN free radical in acetonitrile discharges ». Journal of Applied Physics 93, n^o 12 (15 juin 2003) : 9497–502. http://dx.doi.org/10.1063/1.1575928.

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Bossa, Jean-Baptiste, Fabien Borget, Fabrice Duvernay, Grégoire Danger, Patrice Theulé et Thierry Chiavassa. « Solid-State Methylamine VUV Irradiation Study Using Carbon Monoxide as an H Radical Scavenger ». Australian Journal of Chemistry 65, n^o 2 (2012) : 129. http://dx.doi.org/10.1071/ch11409.

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Solid-phase methylamine (CH3NH2) was vacuum ultraviolet (VUV) photoprocessed at low temperature (20 K) using a hydrogen flow discharge lamp, which allows irradiation down to 120 nm. Methanimine (CH2=NH), the methylammonium cation (CH3NH3+) and the counterion CN–, as well as the amino radical (NH2), methane (CH4) and ammonia (NH3), were identified as the photoproducts by using FTIR spectroscopy. So far, the branching ratios of the photodissociation pathways of methylamine in the solid phase remain unknown. The methylamine molecule holds two non-equivalent hydrogen atoms on the methyl and the amino group, so we can expect the formation of two distinct radicals via a carbon–hydrogen or a nitrogen–hydrogen bond cleavage, namely CH2NH2 and CH3NH. These radicals are highly reactive and may reform methylamine with hydrogen atom recombination. Their direct infrared spectroscopic detection is therefore tricky. To solve that problem, we use carbon monoxide (CO) as an H radical scavenger, forming the intermediate species HCO. After the irradiation of a CH3NH2 : CO binary ice mixture, formamide (NH2CHO) and N-methylformamide (CH3NHCHO) were identified as the main photoproducts using both infrared and mass spectrometry. We give a rough approximation of the branching ratios, which are in agreement with previous studies in the gas phase.

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Khalil, Salim M., et Hayfa M. Jarjis. « A Theoretical Study of Fulvene Radical Anions ». Zeitschrift für Naturforschung A 46, n^o 3 (1 mars 1991) : 247–55. http://dx.doi.org/10.1515/zna-1991-0306.

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AbstractMINDO-Forces calculations have been performed, with complete optimization of geometry on fulvene and X-fulvene radical anions, where X is OH, NH2, CH3, NO,2 CN, F, dimethyl and cyclopropyl. A twisted structure with angle 5° was found for fulvene anion. All substituents are stabilizing. The stabilization effect is more pronounced in the case of NO2, and very weak in the case of CH3. It was found that the substituents CH3 and CN show amphielectronic behaviour. Geometrical parameters, heats of formation, dipole moments, electron and spin densities are reported

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De Almeida, A. A. « Gas Production Rates in Comets ». Symposium - International Astronomical Union 150 (1992) : 443–45. http://dx.doi.org/10.1017/s0074180900090641.

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Emission fluxes of CN, C2 and C3 carbon- bearing molecular species observed in the coma of comets Bennett (1969i ≡ 1970II), West (1975n = 1976VI), P/Halley (1982i), Hartley-Good (1985l) and Bradfield (1987s) are analysed in the framework of Haser model. CN, C2 and C3 production rates are determined using recently derived fluorescence efficiencies. The dependence of CN, C2 and C3 production rates on the heliocentric distance and the possible correlations among these radicals is studied and briefly discussed.

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Sleiman, Chantal, Sergio González, Stephen J. Klippenstein, Dahbia Talbi, Gisèle El Dib et André Canosa. « Pressure dependent low temperature kinetics for CN + CH3CN : competition between chemical reaction and van der Waals complex formation ». Physical Chemistry Chemical Physics 18, n^o 22 (2016) : 15118–32. http://dx.doi.org/10.1039/c6cp01982j.

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The gas phase reaction between the CN radical and acetonitrile CH₃CN was investigated experimentally with a CRESU apparatus and a slow flow reactor as well as theoretically to explore the temperature and pressure dependence of its rate coefficient from 354 K down to 23 K.

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Yao, Zengwu, et Lixin Jiang. « How to improve the lymph node detection and staging accuracy in gastric cancer patients : A randomized controlled trial in single center. » Journal of Clinical Oncology 35, n^o 15_suppl (20 mai 2017) : e15577-e15577. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.e15577.

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e15577 Background: To evaluate the effects of carbon nanoparticles by subserosa injection and different Lymph node retrievals by surgeon or pathologist in improving the positive and total lymph node detection and staging accuracy in patients who undergone the standard D2 gastrectomy. Methods: We collected 200 gastric cancer patients who undergone the standard D2 radical lymph node resection gastrectomy from November 2013 to November 2014 in Gastrointestinal Surgery Ward of Yantai Yuhuangding Hospital. The cases were randomly devidided into 4 groups (N = 50): Pathologist group(PA), surgeon group(SU), surgeon plus carbon nanoparticles group(SU+CN), pathologist plus carbon nanoparticles group (PA+CN) . The number of lymph nodes and the proportion of TNM stages were calculated respectively. Results: In the positive and total number of lymph nodes in all cases, it is significantly higher in Group SU than Group PA (3.64±4.32 VS 2.63±3.45),( 25.46±5.24 VS 20.23±6.32),Group SU+CN than Group PA (4.56±3.86 VS 2.63±3.45 ),(30.76±8.42 VS 20.23±6.32), Group PA+CN than Group PA(3.83±2.09 VS 2.63±3.45),(24.98±6.01 VS 20.23±6.32), Group SU+CN than Group SU(4.56±3.86 VS 2.63±3.45),(30.76±8.42 VS 25.46±5.24), Group SU+CN than Group PA+CN(4.56±3.86 VS 3.83±2.09),( 30.76±8.42 VS 24.98±6.01) (P < 0.05). The proportion of each TNM stage is significantly different in Group SU VS Group PA, Group SU+CN VS Group PA, Group PA+CN VS Group PA, Group SU+CN VS Group SU, Group SU+CN VS Group PA+CN(P < 0.05), while it is similar in Group PA+CN VS Group SU(P < 0.05). The highest proportion of Stage I and II and the lowest proportion of Stage III is in Group PA, and in Group SU+CN by contrary. Multivariate analysis shows carbon nanoparticles by subserosa injection and lymph node retrievals by surgeon are independent factors. Conclusions: Carbon nanoparticles by subserosa injection and lymph node retrievals by surgeon could be used as independent factors to improve the number of positive and total lymph nodes in standard D2 radical lymph node resection gastrectomy. It may also improve the accuracy of pathological staging of gastric cancer patients. Clinical trial information: ChiCTR-TRC-14876411.

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Rosa, Angela, et Giampaolo Ricciardi. « A time-dependent density functional theory (TDDFT) interpretation of the optical spectra of zinc phthalocyanine π-cation and π-anion radicals ». Canadian Journal of Chemistry 87, n^o 7 (juillet 2009) : 994–1005. http://dx.doi.org/10.1139/v09-066.

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The UV–visible and near-IR spectra of the zinc phthalocyanine π-cation and π-anion radicals, [ZnPc(–1)]•+ and [ZnPc(–3)]•–, are investigated by time-dependent density functional theory (TDDFT) calculations using the pure, asymptotically correct, statistical average of (model) orbital potentials (SAOP) functional. The nature and intensity of the main spectral features are highlighted and interpreted on the basis of the ground-state electronic structure of the complexes. Similarities and differences with previous TDDFT/B3LYP results are discussed. TDDFT/SAOP results for the π-anion radical prove to be in excellent agreement with the solution spectra and generally in line with deconvolution analyses of solution absorption and magnetic circular dichroism (MCD) spectra. On the basis of these results a novel interpretation of the Q-band system is proposed. For the π-cation radical TDDFT/SAOP calculations provide a satisfactory description of the UV region of the spectrum. However, they do not reproduce accurately the energy and intensity of the Q band observed at 825 nm. The description of the Q-band region appears to be complicated by the presence of spurious non-Gouterman transitions. Furthermore, the calculations, either in the gas phase or in solution, do not account for the broad absorption near 500 nm that has been suggested to arise from a nondegenerate, z-polarized 2A2g excited state. Theory and experiment can be reconciled if the presence of an axial ligand such as CN– is explicitly considered in the calculations. TDDFT/SAOP results for the axially ligated [ZnPc(–1)(CN)]• species indicate that the 500 nm feature is related to the axial ligation induced symmetry lowering of the π-cation radical and this band is assigned to a z-polarized transition associated with the hole in the 2a1u.

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Paron, S., M. E. Ortega, A. Marinelli, M. B. Areal et N. C. Martinez. « Cyano radical emission at small spatial scales towards massive protostars ». Astronomy & ; Astrophysics 653 (septembre 2021) : A77. http://dx.doi.org/10.1051/0004-6361/202141424.

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Context. The cyano radical (CN), one of the first detected interstellar molecular species, is a key molecule in many astrochemical chains. In particular, it is detected towards molecular cores, the birth places of stars, and it is involved in the rich chemistry that takes place at these sites. Aims. At present, there are not many studies on the emission of this molecular species at small spatial scales towards massive young stellar objects. We therefore present a high-angular resolution CN study towards a sample of massive protostars, with the aim of unveiling the spatial distribution at the small scale of the emission of this radical in relation to star-forming processes. Methods. The interstellar CN has a strong emission line at the rest frequency 226 874.764 MHz, thus we searched for observing projects in the Atacama Large Millimeter Array (ALMA) database regarding high-mass star-forming regions observed at Band 6. The used data set was observed in ALMA Cycle 3 with angular and spectral resolutions of 0.′′7 and 1.13 MHz, respectively. A sample of ten high-mass star-forming regions located in the first Galactic quadrant were selected on the basis that they present a clear emission of CN at the mentioned frequency. Results. We found that the CN traces both molecular condensations and the diffuse and extended gas surrounding them. In general, the molecular condensations traced by the maximums of the CN emission do not spatially coincide with the peaks of the continuum emission at 1.3 mm, which trace the molecular cores where massive stars are born. Based on the presence or lack of near-IR emission associated with such cores, we suggest that our sample is composed of sources at different stages of evolution. The CN is present in all sources, suggesting that this radical may be ubiquitous along the different star formation stages, and hence it may be involved in different chemical reactions occurring during the period of star formation. Additionally, other molecules such as CH3OCHO and CH2CHCN were detected towards the continuum peaks of some of the analysed cores. We found that the missing flux coming from extended spatial scales that are filtered out by the interferometer is an important issue to take into account in the analysis of some spectral features and the spatial distribution of the emission.

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Layuno Rosas, M. Ángeles. « Arquitectura y paisaje de la industria moderna en Alcalá de Henares ». Cuaderno de Notas, n^o 18 (20 novembre 2017) : 199. http://dx.doi.org/10.20868/cn.2017.3608.

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El acelerado crecimiento industrial de municipios como Alcalá de Henares durante las décadas de los años 50 y 60 provocará radicales transformaciones en su morfología y paisaje urbanos, pero, a su vez, la identidad del municipio como ciudad industrial estimulará la aparición de una arquitectura moderna de la industria, símbolo del progreso industrial de la política económica del desarrollismo. Complejos fabriles cuya arquitectura sintetiza los debates internacionales sobre el proyecto industrial moderno en su doble vertiente formal y técnica. En este sentido, la arquitectura industrial de las décadas del desarrollismo supondrá una contribución realista y funcional a la recuperación de la arquitectura moderna en la España del momento.

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Bordwell, Frederick G., et John A. Harrelson Jr. « Acidities and homolytic bond dissociation energies of the αC—H bonds in ketones in DMSO ». Canadian Journal of Chemistry 68, n^o 10 (1 octobre 1990) : 1714–18. http://dx.doi.org/10.1139/v90-266.

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Equilibrium acidities in DMSO are reported for nine cycloalkanones, acetone, acetophenone, and 19 of their α-substituted derivatives. Oxidation potentials in DMSO for the conjugate bases of most of these ketones are also reported. Combination of these EOX(A−) and pKHA values gives estimates of the homolytic bond dissociation energies (BDEs) of the acidic C—H bonds in the ketones. The ΔBDEs, relative to the BDE of CH3-H, or a parent ketone, provide a measure of the radical stabilization energies (RSEs) of the corresponding radicals. The effects of successive α-Me and α-Ph substitutions on RSEs, relative to those of CH3COCH2-H or PhCOCH2-H, are similar to those reported in the gas phase for methane. The RSE for the MeĊHCOPh radical, relative to CH3• is 17 kcal/mol, which is smaller than the sum of the RSEs of the MeCH2• and PhCOCH2• radicals relative to CH3• (7 + 12 = 19), contrary to the prediction of the captodative postulate. When G in PhCOCH2G is PhCO, CH3CO, or CN the ΔBDEs (relative to PhCOCH2-H) are 0, 1, and 3 respectively; for MeCOCH2SO2Ph, PhCOCH2SO2Ph, and PhCOCH2NMe3+ the ΔBDEs are −5, −2, and −4, respectively. The BDEs in C5, C6, C7, C8, C10, and C12 cycloalkanones are within ±2.5 kcal/mol of that of 3-pentanone. Acetophenones bearing meta or para substituents all have BDEs of 93-94 kcal/mol. Ketone radical cations, [RCOR′]+•, appear to be superacids with estimated [Formula: see text] values below −25. Keywords: acidities, bond dissociation energies, ketones.

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Gao, Weifan, Guichang Zhang, Xiaoping Zhang, Shaoqi Zhou et Zihao Wang. « Degradation of Methylene Blue in the Photo-Fenton-Like Process with WO3-Loaded Porous Carbon Nitride Nanosheet Catalyst ». Water 14, n^o 16 (20 août 2022) : 2569. http://dx.doi.org/10.3390/w14162569.

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The catalytic capability of original carbon nitride (CN) is limited by a small specific surface area and high electron–hole recombination rate. In this study, WO3-loaded porous carbon nanosheets (MCA-CN/WO3) were synthesized by thermal treatment with melamine, cyanuric acid and WCl6. The MCA-CN/WO3 could degrade 98% of the methylene blue (MB) within 30 min in the photo-Fenton-like process, displaying better catalytic activity than the original CN (30%), pure MCA-CN (63%) and original CN/WO3 (87%). The results of photoluminescence and electrochemical impedance spectroscopy demonstrated that the Z-scheme heterojunction of MCA-CN/WO3 inhibited the recombination of electrons and holes. In addition, the porous nanosheet structure accelerated the electron transfer and provided abundant active sites for MB degradation. A radical quenching experiment indicated that the Z-scheme heterojunction facilitated the decomposition of H2O2 to produce 1O2 for MB degradation. The possible degradation pathways of MB were proposed.

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Zheng, Kai, Jianan Chen, Xue Gao, Xiaoqing Cao, Shan Wu et Jixin Su. « Synthesis of free-metal composites g-CN/GQDs with enhanced photocatalytic degradation of tetracycline ». E3S Web of Conferences 293 (2021) : 01019. http://dx.doi.org/10.1051/e3sconf/202129301019.

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Developing inexpensive and environmentally friendly no-metal photocatalyst is a promising strategy to addressing environmental issues. In this work, the metal-free catalyst g-CN/GQDs was synthesized through one-pot co-sintering method. The as-prepared photocatalysts showed enhanced photocatalytic activity for tetracycline (TC) degradation. Especially, the g-CN/GQDs-5 exhibited a nearly 30% improvement in TC degradation within 60 min of visible light irradiation compared to g-CN, and the kinetic constant was 1.8 times that of g-CN. The enhanced performance was attributed to the introduction of GQDs enhance the visible light absorption ability and suppress the recombination of photo-generated charges of g-CN. The capture experiment of active species showed that superoxide radicals played a major role in the degradation of TC in this system.

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Koyama, Daisuke, Philip Coulter, Michael P. Grubb, Gregory M. Greetham, Ian P. Clark et Andrew J. Orr-Ewing. « Reaction Dynamics of CN Radicals in Acetonitrile Solutions ». Journal of Physical Chemistry A 119, n^o 52 (17 décembre 2015) : 12924–34. http://dx.doi.org/10.1021/acs.jpca.5b10720.

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Anastasi, Christopher, et Denise U. Hancock. « Reaction of CN radicals with CH4 and O2 ». Journal of the Chemical Society, Faraday Transactions 2 84, n^o 1 (1988) : 9. http://dx.doi.org/10.1039/f29888400009.

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Chaturvedi, V., B. Wong et S. L. Newman. « Oxidative killing of Cryptococcus neoformans by human neutrophils. Evidence that fungal mannitol protects by scavenging reactive oxygen intermediates. » Journal of Immunology 156, n^o 10 (15 mai 1996) : 3836–40. http://dx.doi.org/10.4049/jimmunol.156.10.3836.

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Abstract Polymorphonuclear neutrophils (PMN) kill Cryptococcus neoformans (Cn) by oxidative mechanisms, but the roles of various reactive oxygen intermediates (ROIs) are not known. We used a mannitol low-producing Cn mutant (Cn MLP) and its wild-type parent (Cn H99) to examine the role of ROIs distal to H2O2 in PMN killing and to determine whether mannitol produced by Cn protects the fungus against ROIs. At PMN:Cn cell ratios of 1:1, 10:1, and 100:1, PMN killed significantly more Cn MLP than Cn H99 cells after 2 and 4 h (p less than 0.05). Superoxide dismutase and the hydroxyl radical (OH.) scavengers mannitol and DMSO inhibited killing of both strains (p less than 0.05), but catalase did not. Cn H99 and Cn MLP stimulated PMN to produce similar amounts of O2- and H2O2. In contrast, Cn MLP stimulated greater luminol-dependent chemiluminescence than did Cn H99 (p less than 0.05). Finally, H2O2 alone killed similar numbers of Cn H99 and Cn MLP cells, but oxidants generated by FeSO4 (1 microM), H2O2 (10 microM), and iodide (1 to 3 microM) killed significantly more Cn MLP than Cn H99 cells in 1 h (p less than 0.05). Mannitol, DMSO, and catalase completely inhibited killing of both Cn strains by this cellfree system, but superoxide dismutase did not. These results suggest that 1) distal ROIs such as OH. and HOCI are key effector molecules against Cn, and 2) mannitol produced by Cn may protect against oxidative killing by scavenging distal ROIs.

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Díez Martínez, Daniel. « Hacia Arts & ; Architecture La revolución editorial de John Entenza (1938-1945) ». Cuaderno de Notas, n^o 19 (31 juillet 2018) : 1. http://dx.doi.org/10.20868/cn.2018.3813.

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Resumen En enero de 1945 Arts & Architecture puso en marcha el programa CaseStudy House, un experimento ideado por John Entenza que les reservaríaa él y a su revista un lugar importante en la historia de la arquitectura moderna del siglo XX. Desde que asumió la dirección de Arts & Architectureen 1940, Entenza supo rodearse de creadores y artistas como Alvin Lustig,Ray y Charles Eames, Herbert Matter o Julius Shulman, que contribuyerona elevar el estándar gráfico de su publicación y le confirieron una identidadinnovadora que respaldaba visualmente el discurso intelectual vanguardista de compromiso con la arquitectura y el diseño modernos que defendía en sus páginas. Este artículo analiza los orígenes, las estrategias de trasformación y los nombres propios que hicieron realidad una revista que, cincuenta años después de su desaparición en 1967, sigue resultando tan atractiva y radical como cuando se editaba.AbstractIn January 1945 Arts & Architecture launched the Case Study House program, an experiment devised by John Entenza that would reserve for him and his magazine an important place in the history of modern architecture of the twentieth century. From the moment he took over the direction of Arts & Architecture in 1940, Entenza knew how to seduce creators and artists such as Alvin Lustig, Ray and Charles Eames, Herbert Matter and Julius Shulman, who contributed to raise the graphic standard of his publication and gave it an innovative identity that visually supported the avant-garde intellectual discourse of commitment to modern architecture and design that it defended in its pages. This article analyzesthe origins, the strategies of transformation and the proper names that made the magazine a reality that, fifty years after its disappearance in 1967, continues to be as attractive and radical as when it was published.

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Loison, Jean-Christophe, Xixi Hu, Shanyu Han, Kevin M. Hickson, Hua Guo et Daiqian Xie. « An experimental and theoretical investigation of the N(4S) + C2(1Σg+) reaction at low temperature ». Phys. Chem. Chem. Phys. 16, n^o 27 (2014) : 14212–19. http://dx.doi.org/10.1039/c4cp01801j.

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Platt, Sean P., Isaac K. Attah, M. S. El-Shall, Rifaat Hilal, Shaaban A. Elroby et Saadullah G. Aziz. « Unconventional CHδ+⋯N hydrogen bonding interactions in the stepwise solvation of the naphthalene radical cation by hydrogen cyanide and acetonitrile molecules ». Physical Chemistry Chemical Physics 18, n^o 4 (2016) : 2580–90. http://dx.doi.org/10.1039/c5cp06502j.

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Krełowski, J., G. Galazutdinov et Y. Beletsky. « Unusually high rotational temperature of the CN radical ». Astronomy & ; Astrophysics 531 (15 juin 2011) : A68. http://dx.doi.org/10.1051/0004-6361/201016290.

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Wang, De-Quan, Ji-Lai Li, Xu-Ri Huang, Cai-Yun Geng et Chia-Chung Sun. « Diatomic radical–molecule reactions CN+HONO : Mechanistic study ». Journal of Molecular Structure : THEOCHEM 857, n^o 1-3 (mai 2008) : 20–26. http://dx.doi.org/10.1016/j.theochem.2008.01.030.

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