Journal articles: 'Irradiation par ion'

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Han, X. G., J. F. Lv, Y. Z. Chen, Y. C. Shan, and J. J. Xu. "Influence of irradiation intensity on corrosion properties of microarc oxidation film on AZ31 magnesium alloy with HIPIB." Anti-Corrosion Methods and Materials 66, no. 4 (July 1, 2019): 418–24. http://dx.doi.org/10.1108/acmm-10-2018-2007.

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Purpose The purpose of this paper is to investigate the effect of high-intensity pulsed ion beam (HIPIB) intensity on the structure and corrosive properties of microarc oxidation (MAO) films on AZ31 magnesium alloy and explore the mechanism for modified anti-corrosion properties of irradiated films. Design/methodology/approach The energy deposited on the coating surface influences the remelting process of the MAO coatings significantly, which was closely related to the intensity of HIPIB; therefore, HIPIB with various intensities of 100-350 A/cm2, was selected to modify the MAO films on AZ31 magnesium alloy. The changes in film structure and phase structure of modified films were characterized by scanning electron microscopy and X-ray diffractometry (XRD) with CuKα, respectively. The corrosive behavior of the MAO films was featured with polarization curves and electrochemical impedance spectrum in 3.5 per cent NaCl solution on a PAR 2273 electrochemical workstation. Findings The results clearly show that a dense, continual and remelted layer with a few micrometers in thickness was obtained on the irradiated surface at 200 A/cm2, which are mainly responsible for the modified and optimal anti-corrosion property of MAO films by suppressing/retarding the process of the corrosive electrolyte infiltration into magnesium substrate surface. Originality/value The paper reveals that HIPIB irradiation could modify the corrosion resistance by producing a remelted compact layer on the MAO film surface at a suitable irradiation parameter and explored the modified mechanism of MAO films.

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Gnaser, Hubert. "Nanostructures on surfaces by ion irradiation." Pure and Applied Chemistry 83, no. 11 (July 17, 2011): 2003–25. http://dx.doi.org/10.1351/pac-con-11-03-05.

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The bombardment of the surface of a solid by energetic ions often results in pronounced surface modifications, leading to characteristic topographical features. In this report, the development of specific morphological nanostructures on surfaces under ion irradiation is discussed. The following aspects will be emphasized: (i) on an atomic scale, the generation of isolated defects such as adatoms and surface vacancies due to single-ion impacts, and their possible clustering; (ii) the transition from such individual defects toward extended morphological features on the surface and suitable scaling relations to describe them; (iii) the formation of highly periodic structures with nanoscale dimensions such as nanodots and “ripple”-like features, and the dependence of these nanostructcures on various ion-irradiation parameters and substrate materials; (iv) the theoretical concepts proposed to model the observed patterns which are thought to be related to (and caused by) the interplay between ion erosion and diffusion of adatoms (vacancies), thus inducing a surface reorganization.

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Milosavljević, Srdjan, Djordje Lazarević, Koviljka Stanković, Milić Pejović, and Miloš Vujisić. "Effects of Ion Beam Irradiation on NanoscaleInOxCooper-Pair Insulators." International Journal of Photoenergy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/236823.

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This paper examines the effects of irradiating indium oxide films of nanoscale thickness by ion beams, when these films are in the Cooper-pair insulator state. Radiation effects are predicted on the basis of Monte Carlo simulations of ion transport. Results of numerical experiments are interpreted within the theoretical model of a Cooper-pair insulator. The study suggests that radiation-induced changes inInOxfilms exposed to ion beams could significantly alter their current-voltage characteristics and that a transition to a metallic state is possible, due to radiation-induced perturbation of the fine-tuned granular structure. Furthermore, incident and displaced ions can break up enough Cooper pairs inInOxfilms to cause dissolution of this specific insulating state.

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Jung, Chan-Hee, In-Tae Hwang, Ho-Je Kwon, Young-Chang Nho, and Jae-Hak Choi. "Patterning of cells on a PVC film surface functionalized by ion irradiation." Polymers for Advanced Technologies 21, no. 2 (April 12, 2009): 135–38. http://dx.doi.org/10.1002/pat.1437.

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Sharma, Swati, Mausumi Mukhopadhyay, and Zagabathuni Venkata Panchakshari Murthy. "Photolytic degradation of chlorophenols from industrial wastewaters by organic oxidants peroxy acetic acid, para nitro benzoic acid and methyl ethyl ketone peroxide: identification of reaction products." Water Science and Technology 69, no. 6 (January 2, 2014): 1259–66. http://dx.doi.org/10.2166/wst.2014.001.

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In this investigation, chlorophenol (CP) containing industrial wastewater was remediated by ultraviolet irradiation in conjunction with organic oxidants, peroxy acetic acid (PAA); para nitro benzoic acid (PNBA); and methyl ethyl ketone peroxide (MEKP). CP mineralization was studied with regard to chemical oxygen demand (COD) and chloride ion release under identical test conditions. COD depletion to the extent of 81% by PAA, 66% by PNBA, and 67% by MEKP was noted along with an upwardly mobile trend of chloride ion release upon irradiation of samples at 254 nm. A 90–99% decrease in CP concentration (as per high pressure liquid chromatography (HPLC) analysis) was achieved with an additional 15.0 ml of organic oxidant in all cases. Gas chromatography high resolution mass spectroscopy (GC-HRMS) results also indicated the formation of such reaction products as are free from chlorine substitutions. This treatment also leads to total decolorization of the collected samples.

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KUKSENOVA, L. I., and D. A. KOZLOV. "ALLOYING THE SURFACE OF STEEL 30KHGSN2A TO INCREASE ITS TRIBOLOGICAL CHARACTERISTICS." Fundamental and Applied Problems of Engineering and Technology 4, no. 2 (2020): 55–60. http://dx.doi.org/10.33979/2073-7408-2020-342-4-2-55-60.

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The results of evaluating the wear of samples of the model of the same name pair of friction from alloy steel 30KhGSN2A after ion beam treatment and dry friction under conditions of heavy contact are presented. It was shown that in the steady state friction, the wear resistance of steel as a result of implantation of copper ions at an irradiation dose of 1017 ion / cm2 and 5.1017 ion / cm2 increases by 2 and 1.5 times, respectively. The mechanism of the «long-range effect» in ion-doped structural materials under conditions of contact deformation is discussed.

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Chen, Tao, Junfeng Zhen, Ying Wang, Harold Linnartz, and Alexander G. G. M. Tielens. "Photodissociation processes of Bisanthenquinone cation." Proceedings of the International Astronomical Union 13, S332 (March 2017): 353–59. http://dx.doi.org/10.1017/s1743921317007864.

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AbstractA systematic study, using ion trap time-of-flight mass spectrometry, is presented for the photo-dissociation processes of Bisanthenquinone (Bq) cations, C28H12O2+, a ketone substituted Polycyclic Aromatic Hydrocarbon (PAH). The Bq cation fragments through sequential loss of the two neutral carbonyl (CO) units upon laser (626nm) irradiation, resulting in a PAH-like derivative C26H12+. Upon further irradiation, C26H12+ exhibits both stepwise dehydrogenation and C2/C2H2 loss fragmentation channels. Quantum chemistry calculations reveal a detailed picture for the first CO-loss, which involves a transition state with a barrier of ∼ 3.4 eV, which is lower than the energy required for the lowest H-loss pathway (∼ 5.0 eV). The barrier for the second CO-loss is higher (∼ 4.9 eV). The subsequent loss of this unit changes the Bq geometry from a planar to a bent one. It is concluded that the photodissociation mechanism of the substituted PAH cations studied here is site selective in the substituted subunit. This work also shows that an acetone substituted PAH cation is not photo-stable upon irradiation.

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Feng, Xin, Xinwei Li, Wen Cui, Fan Dong, and Tierui Zhang. "An ion-exchange strategy for I-doped BiOCOOH nanoplates with enhanced visible light photocatalytic NOx removal." Pure and Applied Chemistry 90, no. 2 (February 23, 2018): 353–61. http://dx.doi.org/10.1515/pac-2017-0509.

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Abstract A simple ion-exchange method was developed for I-doped BiOCOOH nanoplates from the replacement of COOH− ions with I− ions in the interlayers of BiOCOOH. The as-prepared catalysts were characterized by XRD, SEM, TEM, XPS, UV-vis DRS PL and photocurrent generation. The photocatalytic activity of the as-prepared catalysts was evaluated by removal of NO in air at ppb level under visible light irradiation. As expected, the I-doped BiOCOOH (IHB-X, the X represents the molar ratio of KI to BiOCOOH) displayed increased visible light absorption and enhanced charge separation due to I-doping. At a saturate I-doping content, the IHB-1.00 catalyst with optimized electronic structure demonstrated the highest NO removal of 49.7% and excellent photochemical stability. This present work has demonstrated a new strategy for modification of layered photocatalyst via ion exchange.

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Hiruma, Hitomi, Shoichiro Asayama, and Hiroyoshi Kawakami. "Control of cell morphology on the polyimide surface patterned by rubbing and ion-irradiation." Polymers for Advanced Technologies 22, no. 8 (April 25, 2011): 1311–14. http://dx.doi.org/10.1002/pat.1949.

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Holdsworth, Eccles, Rowbotham, Bond, Kavi, and Edge. "The Effect of Gamma Irradiation on the Ion Exchange Properties of Caesium-Selective Ammonium Phosphomolybdate-Polyacrylonitrile (AMP-PAN) Composites under Spent Fuel Recycling Conditions." Separations 6, no. 2 (April 24, 2019): 23. http://dx.doi.org/10.3390/separations6020023.

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The caesium radioisotopes 134Cs, 135Cs, and 137Cs are highly problematic medium-lived species produced during nuclear fission, due to their high radioactivity and environmental mobility. While many ion exchange materials can readily isolate Cs+ ions from neutral or basic aqueous solutions, only ammonium phosphomolybdate (AMP) functions effectively in acidic conditions, removing caesium even down to trace levels. Composites of AMP in a porous polymeric support such as polyacrylonitrile (PAN) can be used to selectively remove Cs+ ions from acidic aqueous decontamination liquors as well as other liquid wastes, and are promising for the isolation of Cs+ isotopes in spent fuel reprocessing. While both AMP and PAN have demonstrable acid stability, and PAN has known resistance to gamma radiation, AMP-PAN composites have received only a limited analysis of their physiochemical and ion exchange performance following irradiation. In this publication, we explore the effect of high levels of gamma irradiation on the ion exchange properties of AMP and AMP-PAN as a Cs+-selective adsorbent under spent fuel dissolver liquor concentrations and acidity. We demonstrate no significant reduction in performance with respect to uptake kinetics or capacity upon irradiation, abiding by the same absorption mechanism observed in the established literature.

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Mukhopadhyay, Mausumi, and Dhiraj P. Daswat. "Photochemical degradation of 4-chlorophenol in the aqueous phase using peroxyacetic acid (PAA)." Water Science and Technology 67, no. 2 (January 1, 2013): 440–45. http://dx.doi.org/10.2166/wst.2012.591.

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The photochemical degradation of 4-chlorophenol (4-CP) using ultraviolet irradiation (UV) of 6, 12 and 18 W with peroxyacetic acid (PAA) was studied in a batch reactor. The objective of this work was to investigate degradation and mineralization of 4-CP by PAA. The degradation efficiency increased with increasing UV input. The degradation process was also pH and initial PAA concentration dependent. The optimum conditions for the photochemical degradation of 4-CP as UV input, pH and PAA concentration was found to be 18 W, 9.5 and 3,040 ppm. The reaction efficiency decreased with increasing initial 4-CP concentrations. More than 95% mineralization of 4-CP was achieved with the UV/PAA process. The chloride ion concentration and chemical oxygen demand (COD) was evaluated. The chloride ion concentration and COD were decreased gradually with increasing UV input. Samples were analyzed by high pressure liquid chromatography (HPLC), UV spectrophotometry and gas chromatography–mass spectrometry (GC-MS) for residual concentration and identification of final degraded products.

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Protti, Stefano, Davide Ravelli, Maurizio Fagnoni, and Angelo Albini. "Smooth photogeneration of α,n-didehydrotoluenes (DHTs)." Pure and Applied Chemistry 85, no. 7 (April 25, 2013): 1479–86. http://dx.doi.org/10.1351/pac-con-12-10-03.

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Irradiation of the three isomeric (chlorobenzyl)trimethylsilanes in methanol–water generates the corresponding didehydrotoluenes (DHTs). The process involves expulsion of a chloride ion to give the triplet phenyl cation and ensuing elimination of the trimethylsilyl cation. This straightforward generation of DHT intermediates overcomes a shortcoming of previous methodology (cycloaromatization of enyne-allenes), which is limited to the meta-isomer, and opens the path for understanding the chemistry (and possibly the biological action) of these unusual intermediates.

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Andrianova, N. N., A. M. Borisov, E. S. Mashkova, M. A. Ovchinnikov, M. A. Timofyev, and E. A. Vysotina. "Surface patterns formation by ion irradiation of PAN based сarbon fibers." Vacuum 188 (June 2021): 110177. http://dx.doi.org/10.1016/j.vacuum.2021.110177.

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Borisov, Anatoly M., Valentina A. Gorina, Eugenia S. Mashkova, Mikchail A. Ovchinnikov, Elena G. Cheblakova, Dmitry N. Chernenko, and Nikolay M. Chernenko. "Sorption properties of PAN-based carbon fiber corrugated by ion irradiation." Materials Today: Proceedings 5, no. 12 (2018): 26058–61. http://dx.doi.org/10.1016/j.matpr.2018.08.029.

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Peaker, Anthony R., Vladimir P. Markevich, J. Slotte, K. Kuitunen, F. Tuomisto, A. Satta, Eddy Simoen, I. Capan, B. Pivac, and R. Jačimović. "Vacancy Clusters in Germanium." Solid State Phenomena 131-133 (October 2007): 125–30. http://dx.doi.org/10.4028/www.scientific.net/ssp.131-133.125.

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Fast neutron irradiation of germanium has been used to study vacancy reactions and vacancy clustering in germanium as a model system to understand ion implantation and the vacancy reactions which are responsible for the apparently low n-type doping ceiling in implanted germanium. It is found that at low neutron doses (~1011cm-2) the damage produced is very similar to that resulting from electron or gamma irradiation whereas at higher doses (> 1013cm-2) the damage is similar to that resulting from ion implantation as observed in the region near the peak of a doping implant. Electrical measurements including CV profiling, spreading resistance, Deep- Level Transient-Spectroscopy and high resolution Laplace Deep-Level Transient-Spectroscopy have been used in conjunction with positron annihilation and annealing studies. In germanium most radiation and implantation defects are acceptor like and in n-type material the vacancy is negatively charged. In consequence the coulombic repulsion between two vacancies and between vacancies and other radiation-induced defects mitigates against the formation of complexes so that simple defects such as the vacancy donor pair predominate. However in the case of ion implantation and neutron irradiation it is postulated that localized high concentrations of acceptor like defects produce regions of type inversion in which the vacancy is neutral and can combine with itself or with other radiation induced acceptor like defects. In this paper the progression from simple damage to complex damage with increasing neutron dose is examined.

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Kim, Young-Ah, Jin-Oh Jeong, and Jong-Seok Park. "Preparation and Characterization of Ionic Conductive Poly(acrylic Acid)-Based Silicone Hydrogels for Smart Drug Delivery System." Polymers 13, no. 3 (January 27, 2021): 406. http://dx.doi.org/10.3390/polym13030406.

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In this study, we developed a smart drug delivery system that can efficiently deliver the required amounts of drugs using the excellent ion conductivity of poly(acrylic acid) (PAA) and an electrical stimulus. As a result of its having carboxyl groups, PAA hydrogel can be used in drug delivery patches to release drugs by ionic conductivity. However, PAA hydrogel has low durability and poor mechanical properties. The carboxyl group of PAA was combined with a siloxane group of silicone using electron-beam irradiation to easily form a crosslinked structure. The PAA–silicone hydrogel has excellent mechanical properties. Specifically, the tensile strength increased more than 3.5 times. In addition, we observed its cell compatibility using fluorescence staining and CCK-8 assays and found good cell viability. Finally, it was possible to control the drug delivery rate efficiently using the voltage applied to the ion-conductive hydrogel. As the voltage was increased to 3, 5, and 7 V, the amount of drug released was 53, 88, and 96%, respectively. These excellent properties of the PAA–silicone hydrogel can be used not only for whitening or anti-wrinkling cosmetics but also in medical drug-delivery systems.

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Holdsworth, Eccles, Rowbotham, Brookfield, Collison, Bond, Kavi, and Edge. "The Effect of Gamma Irradiation on the Physiochemical Properties of Caesium-Selective Ammonium Phosphomolybdate–Polyacrylonitrile (AMP–PAN) Composites." Clean Technologies 1, no. 1 (September 19, 2019): 294–310. http://dx.doi.org/10.3390/cleantechnol1010020.

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Managing certain by-products of the nuclear fuel cycle, such as the radioactive isotopes of caesium: 134Cs, 135Cs and 137Cs is challenging due to their environmental mobility and radioactivity. While a great many materials can isolate Cs+ ions from neutral or basic aqueous solutions via ion exchange, few of these, with the exception of ammonium phosphomolybdate (AMP), function effectively in acidic media. The use of AMP, and its porous composite in polyacrylonitrile (PAN) for management of Cs radioisotopes in various nuclear wastes have been known for decades and are well studied, yet the effects of radiation on the physiochemical properties of such composites have only received limited attention to date. In a previous publication, we demonstrated that a 100 kGy gamma irradiation dose has negligible effect on the ion exchange performance of AMP and AMP–PAN with respect to capacity or kinetics under the Cs+ concentrations and acidity found in spent nuclear fuel (SNF) recycling. As a continuation of this prior study, in this publication we explore the effects of gamma irradiation on the physiochemical properties of AMP and AMP–PAN using a range of characterisation methods. The effects of the same gamma dose on the oxidation state of Mo in AMP and AMP–PAN, the thermal degradation of both AMP and AMP–PAN, combined with a first study into the high-temperature degradation AMP, are reported. The implications of irradiation, its possible mechanism, the conditions present in SNF recycling, and for the end-of-life disposal or recycling of these materials are also discussed.

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Masugata, Katsumi, Hironobu Isobe, Keigo Aga, Masami Matsumoto, Shigeo Kawata, Weihua Jiang, and Kiyoshi Yatsui. "Two-dimensional focusing of self-magnetically insulated “Plasma Focus Diode”." Laser and Particle Beams 7, no. 2 (May 1989): 287–303. http://dx.doi.org/10.1017/s0263034600006054.

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A new and simple type of self-magnetically insulated, vacuum ion diode named “Plasma Focus Diode” has been successfully developed with a large solid angle of irradiation and low divergence angle. The diode has a pair of coaxial cylindrical electrodes similar to a Mather-type plasma focus device. Ion-current density of 1·9 kA/cm2 has been obtained on the anode surface under the experimental conditions of diode voltage ∼1·4 MV, diode current ∼180 kA, and pulse width ∼75 ns. The generated ion beam has been two-dimensionally focused (line focusing) with a focusing radius of ∼0·18 mm, giving a maximum ion current density and beam power density at the axis of ∼0·14 MA/cm2 and ∼0·18 TW/cm2, respectively. The motion of electrons in the gap has been numerically simulated by use of a newly developed particle-in-cell computer simulation code, and good agreement has been obtained between the simulation and the experiment.

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Oliveira, P. R. B., R. Martinez, D. Fulvio, and E. F. da Silveira. "Energetic ion irradiation of N2O ices relevant for Solar system surfaces." Monthly Notices of the Royal Astronomical Society 502, no. 1 (January 14, 2021): 1423–32. http://dx.doi.org/10.1093/mnras/stab083.

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ABSTRACT Ices are the dominant surface material of many Solar system objects, such as comets and trans-Neptunian objects. They are continuously exposed to ion bombardment by solar wind ions and cosmic rays, which trigger secondary ion emission, contributing to the exosphere formation. Laboratory studies demonstrated the effects of energetic processing of ices at low temperature, showing the production of molecules and free radicals of astrophysical interest. Nitrous oxide (N2O) is one of the molecular species observed in star-forming sites, reason why it may be present in the ices covering some minor bodies in the outer Solar system. In the current work, N2O ice at 10 K was irradiated by energetic (MeV/u) multicharged heavy ions (e.g. 105Rh and 140Ba); the sputtered species were detected and analysed by the TOF-PDMS technique (time-of-flight plasma desorption mass spectrometry). Small positive and negative secondary ions were identified: N+, N2+, NO+, O+, and O−. The bombardment also induces production of ion cluster series: (N2)nR$_{m}^+$, (NO)nR$_{m}^+$, (N2O)nR$_{m}^+$, where R = N+, N2+, NO+, N2O+, Om+ (n up to ∼ 10, m = 1−3). Their yield distributions follow the sum of two decreasing exponentials, one fast -F and another slow -S, suggesting a two-regime formation. Most of the yield distributions have the same pair of exponential decay constants, around kF ∼ 1.4 and kS ∼ 0.15 u−1. Based on this behavior, an emission description for aggregates is proposed, useful to understand the processes by which neutral and ionized molecular species are delivery to the gas phase in space.

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Milosavljević, Srdjan, Djordje Lazarević, Koviljka Stanković, Milić Pejović, and Miloš Vujisić. "Corrigendum to “Effects of Ion Beam Irradiation on Nanoscale InOx Cooper-Pair Insulators”." International Journal of Photoenergy 2017 (2017): 1. http://dx.doi.org/10.1155/2017/3029101.

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Sailer, Christian F., and Eberhard Riedle. "Photogeneration and reactions of benzhydryl cations and radicals: A complex sequence of mechanisms from femtoseconds to microseconds." Pure and Applied Chemistry 85, no. 7 (June 30, 2013): 1487–98. http://dx.doi.org/10.1351/pac-con-13-04-01.

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Benzhydryl radicals and cations are reactive intermediates central to the understanding of organic reactivity. They can be generated from benzhydryl halides by UV irradiation. We performed transient absorption (TA) measurements over the range from femtoseconds to microseconds to unravel the complete reaction scheme. The 290–720-nm probe range allows the unambiguous monitoring of all fragments. The appearance of the radical is delayed to the optical excitation, the onset of the cation signal is found even later. Ab initio calculations show that this non-rate behavior in the 100 fs range is due to wavepacket motion from the Franck–Condon region to two distinct conical intersections. The rise of the optical signal with a quasi-exponential time of 300 fs is assigned to the planarization and solvation of the photoproducts. The bond cleavage predominantly generates radical pairs. A subsequent electron transfer (ET) transforms radical pairs into ion pairs. Due to the broad interradical distance distribution and the distance dependence, the ET is strongly non-exponential. Part of the ion pairs recombine geminately. The ET and the recombination are terminated by the depletion of close pairs and diffusional separation. The remaining free radicals and cations undergo further reactions in the nanosecond to microsecond regime.

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Melnikov, Anatoly R., Evgeny V. Kalneus, Valeri V. Korolev, Igor G. Dranov, Alexander I. Kruppa, and Dmitri V. Stass. "Highly efficient exciplex formation via radical ion pair recombination in X-irradiated alkane solutions for luminophores with short fluorescence lifetimes." Photochem. Photobiol. Sci. 13, no. 8 (2014): 1169–79. http://dx.doi.org/10.1039/c3pp50432h.

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Virych, P., O. Nadtoka, and N. Kutsevol. "Combination of hydrogel-toluidine blue and light 600 nm for inactivation of Staphylococcus aureus in vitro." Bulletin of Taras Shevchenko National University of Kyiv. Series: Biology 86, no. 3 (2021): 23–27. http://dx.doi.org/10.17721/1728_2748.2021.86.23-27.

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Skin damage is accompanied by bacterial infection of the wound. Different materials are used for accelerate tissue regeneration and minimize bacterial contamination. Also it is prevent the penetration of bacteria to damaged tissues. After the emergence of antibiotic-resistant strains of microorganisms began the search for alternative means of their inactivation. Photosensitizers are used for this purpose. Their maxima of optical absorbance are in the red and infrared regions. The use of such substances provides powerful bactericidal effects, but with low toxicity to surrounding tissues. The aim of the investigation is to determine the effectiveness of combining hydrogels with toluidine blue and irradiation by light of 600 nm to inhibit the in vitro of Staphylococcus aureus growth. Equilibrium is not formed after incubation of hydrogels with toluidine blue after 3 h in aqueous solution. During this time, 57 and 43 % of the photosensitizer is desorbed from the hydrogels PAA and D-PAA, respectively. Process rate depends on the type of polymer. Desorption of TB from D-PAA is 30% faster. Irradiation of the suspension of S. aureus by light of 600 nm reduced the CFU amount by 25 % at a dose more than 4 J/ml. Short incubation (20 min) of the PAA and D-PAA hydrogels in the bacterial suspension and light irradiation (600 nm), the amount of CFU are reduced by 33% and 15 %, respectively. Increasing the incubation time of PAA does not increase the bactericidal effect. Exposure of 80 min D-PAA with TB in a suspension of S. aureus, followed by light irradiation provides inactivation of 50 % CFU. Thus, the D-PAA system with toluidine blue in combination with 600 nm light can be used to inactivate S. aureus.

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Zhen, Junfeng, Yuanyuan Yang, Weiwei Zhang, and Qingfeng Zhu. "Formation and photochemistry of covalently bonded large functional PAH clusters." Astronomy & Astrophysics 628 (August 2019): A57. http://dx.doi.org/10.1051/0004-6361/201935824.

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Polycyclic aromatic hydrocarbon (PAH) molecules belong to a large and diverse chemical family in the interstellar medium (ISM). We study the formation and photochemistry of covalently bonded large functional PAH clusters, dicoronylene (DC, C48H20)/9-vinylanthracene (C16H12) and dicoronylene/9-methylanthracene (C15H12) cluster cations, in the gas phase, and we offer an approach to the evolution of different types of large (covalently bonded) PAH clusters in the ISM. The experiments, which we combined with a quadrupole ion trap and time-of-flight mass spectrometry, show that large functional PAH cluster cations can form by gas-phase condensation through molecular-ion reactions. One group of functional PAH cluster cations contain the vinyl group (−CHCH2), that is, from C16H12DDC+ (e.g., C16H12C48H19+, m/z = 799) to (C16H12)2DDC+ (e.g., (C16H12)2C48H18+, m/z = 1002). The other group of functional PAH cluster cations contain the methyl group (−CH3), that is, from C15H12DDC+ (e.g., C15H12C48H19+, m/z = 787) to (C15H12)2DDC+ (e.g., (C15H12)2C48H18+, m/z = 990). With laser irradiation, the DC/9-vinylanthracene and DC/9-methylanthracene cluster cations show a very complicated dissociation process (e.g., dehydrogenation, −CH3 or −CHCH2 unit losses). We investigate the structure of newly formed PAH cluster cations, the bond energy, and the photodissociation energy for these reaction pathways with quantumchemical calculations. The obtained results provide a general molecular growth route toward large PAH cluster cations (e.g., functional PAH clusters) in a bottom-up formation process and the insight of the functional group (e.g., vinyl, −C2H3 and methyl, −CH3) effect on their evolutionary behavior. In addition, the studies of DC/9-vinylanthracene and DC/9-methylanthracene clusters (94–123 atoms, ∼2 nm in size) also provide a possible way of interpreting the formation processes of nanometer-sized grains in the ISM, especially when functional PAHs are included.

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Ludwig, Jannis, Julian Helberg, Hendrik Zipse, and Rainer Herges. "Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst." Beilstein Journal of Organic Chemistry 16 (August 31, 2020): 2119–26. http://dx.doi.org/10.3762/bjoc.16.179.

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We present the synthesis and the photochemical and catalytic switching properties of an azopyridine as a photoswitchable ligand, covalently attached to a Ni(II)-porphyrin. Upon irradiation with 530 nm (green light), the azopyridine switches to the cis configuration and coordinates with the Ni2+ ion. Light of 435 nm (violet) isomerizes the ligand back to the trans configuration, which decoordinates for steric reasons. This so-called record player design has been used previously to switch the spin state of Ni2+ between singlet and triplet. We now use the coordination/decoordination process to switch the catalytic activity of the dimethylaminopyridine (DMAP) unit. DMAP is a known catalyst in the nitroaldol (Henry) reaction. Upon coordination to the Ni2+ ion, the basicity of the pyridine lone pair is attenuated and hence the catalytic activity is reduced. Decoordination restores the catalytic activity. The rate constants in the two switching states differ by a factor of 2.2, and the catalytic switching is reversible.

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Zhen, Junfeng, Weiwei Zhang, Yuanyuan Yang, and Qingfeng Zhu. "Laboratory study on the fullerene–PAH-derived cluster cations in the gas phase." Monthly Notices of the Royal Astronomical Society 490, no. 3 (October 3, 2019): 3498–507. http://dx.doi.org/10.1093/mnras/stz2680.

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ABSTRACT It is possible that fullerene–polycyclic aromatic hydrocarbon (PAH) clusters or associations of fullerenes with PAHs contain a large fraction of interstellar fullerenes in the interstellar medium. Herein, we report the formation and photofragmentation behaviour of fullerene–PAH derivatives, fullerene/9-vinylanthracene (C16H12) and fullerene/9-methylanthracene (C15H12) cluster cations. Experiments are carried out using a quadrupole ion trap in combination with time-of-flight mass spectrometry in the gas phase. The results show that fullerene (C60)/9-vinylanthracene (e.g. [(C16H12)3C60]+), fullerene (C56 and C58)/9-vinylanthracene (e.g. [(C16H12)4C56]+ and [(C16H12)4C58]+), fullerene (C60)/9-methylanthracene (e.g. [(C15H12)3C60]+), and fullerene (C56 and C58)/9-methylanthracene (e.g. [(C15H12)4C56]+ and [(C15H12)4C58]+) cluster cations, i.e. large fullerene-derived molecules, are formed in the gas phase through the ion–molecule reaction pathway. With irradiation, all fullerene–PAH-derived cluster cations lose their monomolecular groups without other fragmentation channels (e.g. dehydrogenation). The structure of newly formed fullerene–PAH-derived cluster cations and the bond energy for these adduction formation pathways are investigated with theoretical calculations. The obtained results provide a general molecular growth route towards large fullerene–PAH derivatives (e.g. large fullerene-derived molecules) with functional PAHs in a bottom-up formation process and insights into the effect of functional groups (e.g. vinyl, –C2H3, and methyl, –CH3) on their formation and photoevolution behaviours. In addition, the fullerene–PAH-derived clusters (from 83 to 170 atoms in total, or ∼2 nm in size) offer a good model of carbon dust grains, and the relevance to the nanometre-sized carbon dust grain in space is briefly discussed.

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Zhen, Junfeng. "Laboratory formation of large molecules in the gas phase." Astronomy & Astrophysics 623 (March 2019): A102. http://dx.doi.org/10.1051/0004-6361/201834847.

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We report the experimental study on the formation process of large molecules (e.g. a family group of molecular clusters and graphene) in the gas phase. The experiment was carried out using a quadrupole ion trap in combination with time-of-flight mass spectrometry. As the initial molecular precursor, dicoronylene (DC, C48H20)/anthracene (C14H10) cluster cations, the results show that large PAH cluster cations (e.g., (C14H10)C48Hn+, n = [1–19] and (C14H10)C62Hm+, m = [1–25]) and PAH-graphene cluster cations (e.g., (C14H10)nC48+, n = 0, 1, 2, 3 and (C14H10)mC62+, m = 0, 1, 2) are formed by gas-phase condensation under laser irradiation conditions. We infer that these results present in here provide a formation route for interstellar large molecules under the influence of a strong radiation field in the ISM. The relevance of newly formed species to the nanometer-sized dust grain in space is briefly discussed.

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Andrianova, N. N., A. M. Borisov, E. S. Mashkova, M. A. Ovchinnikov, A. V. Makunin, and E. A. Vysotina. "Surface modification of PAN based carbon fibers by high fluence N+ and C+ ion irradiation." Vacuum 205 (November 2022): 111477. http://dx.doi.org/10.1016/j.vacuum.2022.111477.

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Panthi, Gopal, Md Mehedi Hassan, Yun-Su Kuk, Ji Yeon Kim, Hea-Jong Chung, Seong-Tshool Hong, and Mira Park. "Enhanced Antibacterial Property of Sulfate-Doped Ag3PO4 Nanoparticles Supported on PAN Electrospun Nanofibers." Molecules 25, no. 6 (March 19, 2020): 1411. http://dx.doi.org/10.3390/molecules25061411.

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Heterojunction nanofibers of PAN decorated with sulfate doped Ag3PO4 nanoparticles (SO42−-Ag3PO4/PAN electrospun nanofibers) were successfully fabricated by combining simple and versatile electrospinning technique with ion exchange reaction. The novel material possessing good flexibility could exhibit superior antibacterial property over sulfate undoped species (Ag3PO4/PAN electrospun nanofibers). FESEM, XRD, FTIR, XPS and DRS were applied to characterize the morphology, phase structure, bonding configuration, elemental composition, and optical properties of the as fabricated samples. FESEM characterization confirmed the successful incorporation of SO42−-Ag3PO4 nanoparticles on PAN electrospun nanofibers. The doping of SO42− ions into Ag3PO4 crystal lattice by replacing PO43− ions can provide sufficient electron-hole separation capability to the SO42−-Ag3PO4/PAN heterojunction to generate reactive oxygen species (ROS) under visible light irradiation and enhances its antibacterial performance. Finally, we hope this work may offer a new paradigm to design and fabricate other types of flexible self-supporting negative-ions-doped heterojunction nanofibers using electrospinning technique for bactericidal applications.

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Arutyunov, N. Yu, Valentin V. Emtsev, E. Sayed, and Reinhard Krause-Rehberg. "Configuration of DV Complexes In Ge: Positron Probing of Ion Cores." Solid State Phenomena 131-133 (October 2007): 89–94. http://dx.doi.org/10.4028/www.scientific.net/ssp.131-133.89.

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Angular correlation of annihilation radiation technique (ACAR) has been used for studying a microstructure of the vacancy-group-V-impurity complexes (DV) formed by irradiation with 60Co γ – rays at Tirr. ≈ 280K in oxygen-lean n-Ge doped with group-V-impurity atoms As, Sb, and Bi. The probability of annihilation of positrons with the core electrons of DV complexes to be reconstructed from ACAR spectra has been analyzed on the basis of Chapman-Kolmogorov formalism; the Coulomb repulsion is proved to regulate the penetration of a positron into Ge4+ and D5+ ion cores. In passing from AsV to SbV and BiV complexes the ion cores D5+ are found to contribute more effectively to the probability of the positron annihilation in the core region. These data correlate well with the augmentation of the entropy of ionization (4S ~ 2,9 ÷ 4,2K) observed by means of capacitance transient techniques with the use of Au-Ge Schottky barriers in the same row of a similar vacancy-impurity complexes. The results obtained by ACAR spectroscopy suggest the full-vacancy configuration of DV pair with relaxation of atoms inward towards the vacancy.

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Krivina, L., I. Tsareva, and Yu Tarasenko. "Ion beam technology for the resource enhancement of responsible parts of a high speed friction unit." Journal of Physics: Conference Series 2131, no. 4 (December 1, 2021): 042014. http://dx.doi.org/10.1088/1742-6596/2131/4/042014.

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Abstract The needles from carbon steel “U10”, a details of high speed couple of friction “needle-thrust plate” of the gas centrifuge is investigated, in the initial, post-operational state and after irradiation by C+ ions different doses on the pulse-frequency “Raduga” accelerator. The purpose of this study is to increase the operability and service life of the responsible friction unit of the gas centrifuge. This purpose is achieved by mod-ification of the working sliding surface of the needle (which is a responsible part of the high-speed friction pair “needle-thrust plate”) by the pulse-frequency implantation with carbon ions. The dose of implantation (1018 cm−2 of C+ ions), was established, at which an optimal combination of mechanical and tribological properties of the working surface is achieved, which provides wear resistance increase during the operation of the friction pair. This method of surface treatment is recommended to use in case of operation of couple of friction “needle-thrust plate” for the purpose of increase in working capacity and a resource of operation of high speed couple of friction of the gas centrifuge.

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McMahon, Kevin, and Donald R. Arnold. "The photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction (Part 4): methanol–olefins, methyl 4-cyanobenzoate." Canadian Journal of Chemistry 71, no. 4 (April 1, 1993): 450–68. http://dx.doi.org/10.1139/v93-066.

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Dicyanobenzene-1,4 (1) and -1,2 are known to undergo substitution upon irradiation, in the presence of an olefin, in acetonitrile–methanol (3:1) solution. The products are 1:1:1 (methanol:olefin:aromatic) adducts, substituted on the aromatic ring with loss of a cyano group. This reaction, referred to as the photo-NOCAS (nucleophile–olefin combination, aromatic substitution) reaction, has been shown to be fairly general with regard to the olefin and the nucleophile that can be incorporated. Less is known about the scope of the reaction incorporating other electron-withdrawing substituted aromatic molecules. The purpose of this study was to determine if methyl 4-cyanobenzoate (10) would also take part in this reaction, to form 4-substituted aromatic esters. Irradiation of acetonitrile–methanol solutions of 10 and olefins 2,3-dimethyl-2-butene (2) and 1-methylcyclohexene (5) gave cyclic imine esters, 11 and 13, respectively, instead of photo-NOCAS products. The photo-NOCAS products were obtained when the codonor biphenyl (4) was added to the irradiation mixture. Formation of the cyclic imine ester is attributed to excitation of the charge-transfer complex formed between 10 and the olefin. The addition of biphenyl (4) serves to generate the contact radical ion pair (CRIP) upon irradiation of the charge-transfer complex between 10 and 4. This CRIP can dissociate to the solvent-separated radical ions, the radical cation of 4 can accept an electron from the olefin, and the olefin radical cation can go on to give the photo-NOCAS products. Irradiation of a solution of 10 and 2 in nonpolar solvent (benzene) gave the oxetane, believed to arise from the exciplex. In addition to photo-NOCAS products from 10, 4-cyanophenylketones 17 and 23 are also formed by attack of the β-alkoxyalkyl radical at the carboxyl carbonyl. The differences in behaviour between 1,4-dicyanobenzene (1) and methyl 4-cyanobenzoate (10) under these reaction conditions are described and explained.

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Poddutoori, Prashanth K., Ann Dion, Songjie Yang, Melanie Pilkington, John D. Wallis, and Art van der Est. "Light-induced hole transfer in a hypervalent phosphorus(V) octaethylporphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene." Journal of Porphyrins and Phthalocyanines 14, no. 02 (February 2010): 178–87. http://dx.doi.org/10.1142/s108842461000191x.

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A phosphorus(V) porphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene, dyad 1, and its radical cation phosphorus(V) porphyrin- O-CH2 -(bis(ethylenedithio)tetrathiafulvalene)+•, dyad 2, have been synthesized and studied as an electron hole donor-acceptor system. The absorption spectrum of dyad 1 does not show evidence for electronic coupling between the porphyrin and the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) moieties. However, the steady-state fluorescence of the porphyrin chromophore is quantitatively quenched and its transient fluorescence lifetime is shortened compared to a reference compound in which the BEDT-TTF moiety is replaced by a methoxy group. Chemical oxidation of the BEDT-TTF moiety in dyad 1 to give dyad 2 results in recovery of the fluorescence intensity. This behavior suggests that the fluorescence quenching in dyad 1 is the result of intramolecular hole transfer from the the excited porphyrin to the BEDT-TTF moiety. The occurence of hole transfer in dyad 1 is confirmed by freeze-trapping and time-resolved electron paramagnetic resonance (EPR) measurements. The freeze-trapping EPR experiments show that steady-state irradiation of the complex leads to accumulation of its radical cation (dyad 2) while the transient EPR measurements at 5 °C show that flash irradiation of dyad 1 results in formation of a radical-ion pair with a lifetime of at least 300 ns. The triplet state of the porphyrin, which is formed by intersystem crossing and gives a strong transient EPR spectrum in the reference compound, is not observed for dyad 1. Together, the fluorescence quenching and the polarization pattern of the radical pair suggest that the hole transfer occurs from the excited singlet state of the porphyrin with high efficiency.

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Vujisic, Milos, Dusan Matijasevic, Edin Dolicanin, and Predrag Osmokrovic. "Simulated radiation effects in the superinsulating phase of titanium nitride films." Nuclear Technology and Radiation Protection 26, no. 3 (2011): 254–60. http://dx.doi.org/10.2298/ntrp1103254v.

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This paper investigates possible effects of alpha particle and ion beam irradiation on the properties of the superinsulating phase, recently observed in titanium nitride films, by using numerical simulation of particle transport. Unique physical properties of the superinsulating state are considered by relying on a two-dimensional Josephson junction array as a model of material structure. It is suggested that radiation-induced change of the Josephson junction charging energy would not affect the current-voltage characteristics of the superinsulating film significantly. However, it is theorized that a relapse to an insulating state with thermally activated resistance is possible, due to radiation-induced disruption of the fine-tuned granular structure. The breaking of Cooper pairs caused by incident and displaced ions may also destroy the conditions for a superinsulating phase to exist. Finally, even the energy loss to phonons can influence the superinsulating state, by increasing the effective temperature of the phonon thermostat, thereby reestablishing means for an energy exchange that can support Cooper pair tunneling.

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Plewnia, A., B. Heinz, and P. Ziemann. "Amorphization of metal films by low temperature ion irradiation. An in situ PAC-study for AuIn2 and In3Pd films." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 148, no. 1-4 (January 1999): 901–6. http://dx.doi.org/10.1016/s0168-583x(98)00663-6.

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Jao, Yu-Chen, Meng-Kai Chen, and Shu-Yi Lin. "Enhanced quantum yield of dendrimer-entrapped gold nanodots by a specific ion-pair association and microwave irradiation for bioimaging." Chemical Communications 46, no. 15 (2010): 2626. http://dx.doi.org/10.1039/b926364k.

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Zhang, Lilan, Junfeng Niu, Duo Li, Ding Gao, and Jianghong Shi. "Preparation and Photocatalytic Activity of Ag Modified Ti-Doped-Bi2O3Photocatalyst." Advances in Condensed Matter Physics 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/749354.

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Ti doped Bi2O3(TDB) and Ag ion modified Ti doped Bi2O3(Ag@TDB) photocatalysts were prepared by framework replacement synthesis method with different Ag loadings (0.05, 0.3, 0.75, and 1.0 mol/L AgNO3). The structural properties of the prepared catalysts were studied by scanning electron microscope (SEM), X-ray diffraction (XRD), BET surface area, and UV/Vis diffuse reflectance (DRS). The XRD spectra of the Ti doped Bi2O3calcined at 650°C showed the diffraction peaks of a mixture of Bi12TiO20and Bi4Ti3O12, with bits of mixed crystallite consisting of TiO2and B2O3. A high blue shift in the range 650–550 nm was detected in the DRS band. This blue shift increased with the decreasing Ag content. The photocatalytic activities of the catalysts were evaluated for the degradation of crystal violet (CV) under UV light irradiation. The results indicated that the degradation rate of CV by using 1.0 mol/L AgNO3doped bismuth titanate composite photocatalyst (1.0 Ag@TDB) was 1.9 times higher than that by using the bare Ti doped Bi2O3photocatalyst. The higher activity of Ag@TDB is due to the enhancement of electron-hole pair separation by the electron trapping of silver particles.

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Mahlambi, Mphilisi M., Ajay K. Mishra, Shivani B. Mishra, Ashok M. Raichur, Bhekie B. Mamba, and Rui W. Krause. "Layer-by-Layer Self-Assembled Metal-Ion- (Ag-, Co-, Ni-, and Pd-) DopedTiO2Nanoparticles: Synthesis, Characterisation, and Visible Light Degradation of Rhodamine B." Journal of Nanomaterials 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/302046.

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Metal-ion- (Ag, Co, Ni and Pd) doped titania nanocatalysts were successfully deposited on glass slides by layer-by-layer (LbL) self-assembly technique using a poly(styrene sulfonate sodium salt) (PSS) and poly(allylamine hydrochloride) (PAH) polyelectrolyte system. Solid diffuse reflectance (SDR) studies showed a linear increase in absorbance at 416 nm with increase in the number of m-TiO2thin films. The LbL assembled thin films were tested for their photocatalytic activity through the degradation of Rhodamine B under visible-light illumination. From the scanning electron microscope (SEM), the thin films had a porous morphology and the atomic force microscope (AFM) studies showed “rough” surfaces. The porous and rough surface morphology resulted in high surface areas hence the high photocatalytic degradation (up to 97% over a 6.5 h irradiation period) using visible-light observed. Increasing the number of multilayers deposited on the glass slides resulted in increased film thickness and an increased rate of photodegradation due to increase in the availability of more nanocatalysts (more sites for photodegradation). The LbL assembled thin films had strong adhesion properties which made them highly stable thus displaying the same efficiencies after five (5) reusability cycles.

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Bryson, K. L., F. Salama, A. Elsaesser, Z. Peeters, A. J. Ricco, B. H. Foing, and Y. Goreva. "First results of the ORGANIC experiment on EXPOSE-R on the ISS." International Journal of Astrobiology 14, no. 1 (November 25, 2014): 55–66. http://dx.doi.org/10.1017/s1473550414000597.

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AbstractThe ORGANIC experiment on EXPOSE-R spent 682 days outside the International Space Station, providing continuous exposure to the cosmic-, solar- and trapped-particle radiation background for fourteen samples: 11 polycyclic aromatic hydrocarbons (PAHs) and three fullerenes. The thin films of the ORGANIC experiment received, during space exposure, an irradiation dose of the order of 14 000 MJ m−2 over 2900 h of unshadowed solar illumination. Extensive analyses were performed on the returned samples and the results compared to ground control measurements. Analytical studies of the returned samples included spectral measurements from the vacuum ultraviolet to the infrared range and time-of-flight secondary ion mass spectrometry. Limited spectral changes were observed in most cases pointing to the stability of PAHs and fullerenes under space exposure conditions. Furthermore, the results of these experiments confirm the known trend in the stability of PAH species according to molecular structure: compact PAHs are more stable than non-compact PAHs, which are themselves more stable than PAHs containing heteroatoms, the last category being the most prone to degradation in the space environment. We estimate a depletion rate of the order of 85 ± 5% over the 17 equivalent weeks of continuous unshadowed solar exposure in the most extreme case tetracene (smallest, non-compact PAH sample). The insignificant spectral changes (below 10%) measured for solid films of large or compact PAHs and fullerenes indicate a high stability under the range of space exposure conditions investigated on EXPOSE-R.

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Yang, Yuanyuan, Xiaoyi Hu, Deping Zhang, Weiwei Zhang, Guilin Liu, and Junfeng Zhen. "Laboratory formation and photochemistry of covalently bonded polycyclic aromatic nitrogen heterocycle (PANH) clusters in the gas phase." Monthly Notices of the Royal Astronomical Society 498, no. 1 (July 29, 2020): 1–11. http://dx.doi.org/10.1093/mnras/staa2212.

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ABSTRACT To examine the evolution processes of the nitrogen-containing polycyclic aromatic hydrocarbon (PAH) molecules occurring in interstellar environments, in this work we focus on the formation of large covalently bonded N-substituted polyaromatic species and their photochemistry behaviour in the gas phase. The experimental results show large PANH (e.g. DC/acridine and DC/phenazine) cluster cations formed in a chemical reaction between large PAH (e.g. dicoronylene, DC, C48H20) cations and small PANHs (e.g. acridine, C13H9N, or phenazine, C12H8N2) by gas-phase condensation through ion–molecule reactions. With laser irradiation, PANH cluster cations are involved in a complex photofragmentation process (e.g. dehydrogenation, HCN/CN, C2 or N2 units lost) and then form large PANH/PAH or multiple dehydrogenated molecules; in particular, the dehydrogenation of PANH clusters provides a possible way to synthesize large nitrogen-containing graphene species (e.g. C59N+ and C61N+). Also, we perform quantum-theoretical calculations on the formation and photochemistry of DC/acridine and DC/phenazine cluster cations: two types of molecular cluster are considered (C–C and C–N bond type) and the formation pathway and dissociation energy for each isomer are determined. The experimental and theoretical findings obtained give a general molecular growth pathway toward all-benzenoid aromatic species with size (> 60 C atoms) in the astrophysically relevant range, during a ground-up formation process, and offer understanding of the nitrogen element effect on their chemical-evolutionary behaviour. Also, studies of DC/acridine and DC/phenazine clusters (89–112 atoms, ∼2 nm in size) offer a feasible means of explanation for the formation of nanoscale dust grains (nitrogen element included) in space.

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Fletcher, MT, G. Takken, BJ Blaney, and V. Alberts. "Isoquinoline alkaloids and keto-fatty acids of Argemone ochroleuca and A. mexicana (mexican poppy) seed. I. An assay method and factors affecting their concentration." Australian Journal of Agricultural Research 44, no. 2 (1993): 265. http://dx.doi.org/10.1071/ar9930265.

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An assay for the isoquinoline alkaloids of Argemone ochroleuca and A. mexicana seeds is described. The method consists of extraction into weakly acidified methanol and ion-pair high performance liquid chromatography with sodium lauryl sulfate and tartaric acid in acetonitri1e:water as eluent. Analysis of A. ochroleuca seed showed it to contain dihydrosanguinarine and dihydrochelerythrine (c. 3 : 2) as major alkaloid components with minor amounts of protopine, sanguinarine, berberine and chelerythrine. A single sample of authenticated A. mexicana seed contained dihydrosanguinarine as the major alkaloid with minor amounts of sanguinarine and berberine, in agreement with earlier studies. Dihydrosanguinarine and dihydrochelerythrine were measured as their oxidized products, sanguinarine and chelerythrine, after U.V. irradiation. A crystalline solid which separates from A. ochroleuca seed oil was shown to contain 11-oxo-octacosanoic acid and 11-oxo-triacontanoic acid, which are also the major components of a similar solid from A. mexicana seed oil. Mexican poppy seed (probably A. ochroleuca) collected from various regions of Queensland during 1987-89 showed that place of origin and length of storage of intact seed had little effect on alkaloid levels. Exposure of crushed seed to light, however, caused a rapid decrease in the concentration of dihydro-alkaloids. Total alkaloid content correlated with seed maturity, with immature seed containing much less than mature seed.

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Journal, Baghdad Science. "CFIA-Turbidimetric and Photometric Determination of Vitamin B9 (Folic acid) Using LEDs as a Source of Irradiation and Two Solar Cells as an Energy Transducer." Baghdad Science Journal 14, no. 4 (December 3, 2017): 773–86. http://dx.doi.org/10.21123/bsj.14.4.773-786.

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A specific, sensitive and simple method was used for the determination of: vitamin B9 (Folic acid) in pure and pharmaceutical formulations using continuous flow injection analysis. The method is based on formation of ion pair compound between folic acid and ammonium molybdate in an aqueous medium to obtain a gray precipitate complex, using homemade; Ayah-6SX1-ST-2D solar cell CFI Analyzer. Optimum parameters was studied to increase the sensitivity for developed method. The linear range for the calibration graph was 0.01-0.6 mMol.L-1 of vitamin B9 and LOD was 131.994 ng/sample with correlation coefficient ( r ) of 0.9810, RSD% was lower than 0.1%, (n=9) for the determination of vitamin B9 at concentration (0.07and 0.5) mMol.L-1 respectively. The developed method was applied successfully for the determination of vitamin B9 in pharmaceutical tablets. A comparison was made between two methods: developed method and the classical UV spectrophotometric method at ?max=255 nm, by using the standard addition method via the use of paired t-test. It showed that there was no significant difference between the developed method and the classical method for determination vitamin B9 at 95% confidence level.

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Bass, H., T. Mosmann, and S. Strober. "Evidence for mouse Th1- and Th2-like helper T cells in vivo. Selective reduction of Th1-like cells after total lymphoid irradiation." Journal of Experimental Medicine 170, no. 5 (November 1, 1989): 1495–511. http://dx.doi.org/10.1084/jem.170.5.1495.

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Purified CD4+ BALB/c spleen T cells obtained 4-6 wk after total lymphoid irradiation (TLI) helped normal syngeneic B cells to produce a vigorous antibody response to TNP keyhole limpet hemocyanin in adoptive cell transfer experiments. However, the same cells failed to transfer delayed-type hypersensitivity to the adoptive hosts as measured by a foot pad swelling assay. In addition, purified CD4+ cells from TLI-treated mice were unable to induce graft vs. host disease in lethally irradiated allogeneic C57BL/Ka recipient mice. In response to mitogen stimulation, unfractionated spleen cells obtained from TLI mice secreted normal levels of IL-4 and IL-5, but markedly reduced levels of IL-2 and INF-gamma. A total of 229 CD4+ clones from spleen cells of both normal and TLI-treated mice were established, and the cytokine secretion pattern from each clone was analyzed. The results demonstrate that the ratio of Th1- and Th2-like clones in the spleens of normal BALB/c mice is 1:0.6, whereas the ratio in TLI mice is approximately 1:7. These results suggest that Th2-like cells recover rapidly (at approximately 4-6 wk) after TLI treatment and account for the early return of antibody helper activity and secretion of IL-4 and IL-5, but Th1-like cells recover more slowly (in approximately 3 mo) after irradiation, and this accounts for the deficit in cell-mediated immunity and the reduced amount of IL-2 and IFN-gamma secretion.

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Jones, Guilford, William A. Haney, and Xuan T. Phan. "Photoaddition and photoreduction of chloranil with arenes via singlet and triplet excited complexes. Effects of irradiation wavelength and radical-ion pair spin multiplicity." Journal of the American Chemical Society 110, no. 6 (March 1988): 1922–29. http://dx.doi.org/10.1021/ja00214a043.

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Feng, Feng, Jiamei Liu, Mingxing Zhao, Lu Yu, Haixin Wang, Chunshan Lu, Qunfeng Zhang, et al. "Study of an Environmentally Friendly Method for the Dissolution of Precious Metal with Ionic Liquid and Iodoalkane." Metals 11, no. 6 (June 4, 2021): 919. http://dx.doi.org/10.3390/met11060919.

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Gold as a precious metal resource has high recycling significance. However, the current extraction methods cannot achieve the both efficiency and environmental friendliness. In this paper, we propose a new gold leaching agent, which can leach gold under light condition by mixing iodoform (CHI3) with 1-butyl-3-methylimidazolium dicyanamide (BmimN(CN)2) ionic liquid. Under 25 °C and 13 W incandescent lamp irradiation, the leaching yield of gold can achieve 100 wt%, and the average leaching rate is 945 mg Au/(h·mol·CHI3) (18.9 times of that of the cyanidation method). Through the analysis of the results of radical inhibition experiment, UV-Vis and XPS, a possible leaching mechanism is proposed: the iodine radical generated by light oxidizes Au0 to Au+, and then forms AuN(CN)2 by coordinating with N(CN)2−. Subsequently, the ionic liquid and Au N(CN)2 form a stable [Bmim]·[Au(N(CN)2)2] ion pair structure, further promoting the dissolution reaction. The leaching yield of gold can reach 81.9 wt% and 100 wt%, respectively, when applied to ore and waste electrical and electronic equipment (WEEE); the leaching yield of gold can also reach 100 wt% when applied to a waste catalyst by adding a Soxhlet extraction. The results show that this method is not only efficient, mild, and environmentally friendly, but also has strong adaptability and wide application prospects.

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Marciniak, A., C. Joblin, G. Mulas, V. Rao Mundlapati, and A. Bonnamy. "Photodissociation of aliphatic PAH derivatives under relevant astrophysical conditions." Astronomy & Astrophysics 652 (August 2021): A42. http://dx.doi.org/10.1051/0004-6361/202140737.

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Abstract:

Context. The interaction of polycyclic aromatic hydrocarbons (PAHs) with vacuum ultraviolet (VUV) photons triggers the emission of the well-known aromatic infrared bands (AIBs), but other mechanisms, such as fragmentation, can be involved in this interaction. Fragmentation leads to selection effects that favor specific sizes and structures. Aims. Our aim is to investigate the impact of aliphatic bonds on the VUV photostability of PAH cations in a cryogenic and collisionless environment with conditions applicable for photodissociation regions (PDRs). Methods. The studied species are derived from pyrene (C16H10) and coronene (C24H12) and contain aliphatic bonds either in the form of methyl or ethyl sidegroups or of superhydrogenation. Their cations are produced by laser desorption ionization and isolated in the cryogenic ion cell of the PIRENEA setup, where they are submitted to VUV photons of 10.5 eV energy over long timescales (~1000 s). The parent and fragment ions are mass-analyzed and their relative intensities are recorded as a function of the irradiation time. The fragmentation cascades are analyzed with a simple kinetics model from which we identify fragmentation pathways and derive fragmentation rates and branching ratios for both the parents and their main fragments. Results. Aliphatic PAH derivatives are found to have a higher fragmentation rate and a higher carbon to hydrogen loss compared to regular PAHs. On the other hand, the fragmentation of PAHs with alkylated sidegroups forms species with peripheral pentagonal cycles, which can be as stable as, or even more stable than, the bare PAH cations. This stability is quantified for the main ions involved in the fragmentation cascades by the comparison of the fragmentation rates with the photoabsorption rates derived from theoretical photoabsorption cross sections. The most stable species for which there is an effective competition of fragmentation with isomerization and radiative cooling are identified, providing clues on the structures favored in PDRs. Conclusions. This work supports a scenario in which the evaporation of nanograins with a mixed aliphatic and aromatic composition followed by VUV photoprocessing results in both the production of the carriers of the 3.4 μm AIB by methyl sidegroups and in an abundant source of small hydrocarbons at the border of PDRs. An additional side effect is the efficient formation of stable PAHs that contain some peripheral pentagonal rings. Our experiments also support the role of isomerization processes in PAH photofragmentation, including the H-migration process, which could lead to an additional contribution to the 3.4 μm AIB.

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Gebremendhin, Debebe, Brian Lindemer, Dorothee Weihrauch, David R. Harder, and Nicole L. Lohr. "Electromagnetic energy (670 nm) stimulates vasodilation through activation of the large conductance potassium channel (BKCa)." PLOS ONE 16, no. 10 (October 5, 2021): e0257896. http://dx.doi.org/10.1371/journal.pone.0257896.

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Abstract:

Introduction Peripheral artery disease (PAD) is a highly morbid condition in which impaired blood flow to the limbs leads to pain and tissue loss. Previously we identified 670 nm electromagnetic energy (R/NIR) to increase nitric oxide levels in cells and tissue. NO elicits relaxation of smooth muscle (SMC) by stimulating potassium efflux and membrane hyperpolarization. The actions of energy on ion channel activity have yet to be explored. Here we hypothesized R/NIR stimulates vasodilation through activation of potassium channels in SMC. Methods Femoral arteries or facial arteries from C57Bl/6 and Slo1-/- mice were isolated, pressurized to 60 mmHg, pre-constricted with U46619, and irradiated twice with energy R/NIR (10 mW/cm2 for 5 min) with a 10 min dark period between irradiations. Single-channel K+ currents were recorded at room temperature from cell-attached and excised inside-out membrane patches of freshly isolated mouse femoral arterial muscle cells using the patch-clamp technique. Results R/NIR stimulated vasodilation requires functional activation of the large conductance potassium channels. There is a voltage dependent outward current in SMC with light stimulation, which is due to increases in the open state probability of channel opening. R/NIR modulation of channel opening is eliminated pharmacologically (paxilline) and genetically (BKca α subunit knockout). There is no direct action of light to modulate channel activity as excised patches did not increase the open state probability of channel opening. Conclusion R/NIR vasodilation requires indirect activation of the BKca channel.

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Haga, Naoki, Hiroyuki Nakajima, Hiroaki Takayanagi, and Katsumi Tokumaru. "Photoinduced Electron Transfer between Acenaphthylene and Tetracyanoethylene: Effect of Irradiation Mode on Reactivity of the Charge-Transfer Complex and the Resulted Radical Ion Pair in Solution and Crystalline State." Journal of Organic Chemistry 63, no. 16 (August 1998): 5372–84. http://dx.doi.org/10.1021/jo9801824.

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HAGA, N., H. NAKAJIMA, H. TAKAYANAGI, and K. TOKUMARU. "ChemInform Abstract: Photoinduced Electron Transfer Between Acenaphthylene and Tetracyanoethylene: Effect of Irradiation Mode on Reactivity of the Charge-Transfer Complex and the Resulted Radical Ion Pair in Solution and Crystalline State." ChemInform 29, no. 48 (June 18, 2010): no. http://dx.doi.org/10.1002/chin.199848041.

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Xu, Jinqi, and Richard G. Weiss. "Analyses of In-Cage Singlet Radical-Pair Motions from Irradiations of 1-Naphthyl (R)-1-Phenylethyl Ether and 1-Naphthyl (R)-2-Phenylpropanoate inn-Alkanes." Journal of Organic Chemistry 70, no. 4 (February 2005): 1243–52. http://dx.doi.org/10.1021/jo048182t.

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Journal articles on the topic 'Irradiation par ion'

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