Log in

Relevant bibliographies by topics / Photochemically / Journal articles

To see the other types of publications on this topic, follow the link: Photochemically.

Journal articles on the topic 'Photochemically'

Author: Grafiati

Published: 5 June 2025

Last updated: 24 June 2025

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Photochemically.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Ghosh, Tamal, Amrita Das, and Burkhard König. "Photocatalytic N-formylation of amines via a reductive quenching cycle in the presence of air." Organic & Biomolecular Chemistry 15, no. 12 (2017): 2536–40. http://dx.doi.org/10.1039/c7ob00250e.

Full text

Abstract:

Photochemical N-formylation of amines was achieved without any additional formylating agents in the presence of air. Mechanistic investigations suggest a reaction pathway proceeding via the addition of in situ formed radical cations of enamines with photochemically generated superoxide radical anions.

APA, Harvard, Vancouver, ISO, and other styles

2

Smolikova, G. N., N. V. Stepanova, A. M. Kamionskaya, and S. S. Medvedev. "Photochemical activity in developing pea (<i>Pisum sativum</i> L.) cotyledons depends on the light transmittance of covering tissues and the spectral composition of light." Vavilov Journal of Genetics and Breeding 27, no. 8 (2023): 980–87. http://dx.doi.org/10.18699/vjgb-23-113.

Full text

Abstract:

Many crops require not only leaf photosynthesis for their seed development but also the photochemical reactions that occur in the seeds. The purpose of this work was a comparative analysis of light transmittance and photochemical activity in the leaves of Pisum sativum L. and its pericarp, seed coat, and cotyledons at the early, middle, and late maturation stages. The spectral composition of light was measured using a spectroradiometer in the range of 390–760 nm. We assessed the light transmittance of plant tissues by placing the plant tissue between the light source and the spectroradiometer’s sensor. PAM fluorometry was used to quantify the photochemical activity in plant tissues: this technique is handy for evaluating the efficiency of converting light energy into chemical energy through the analysis of the kinetics of chlorophyll fluorescence excitation and quenching. On average, a photochemically active green leaf of pea transmitted 15 % of solar radiation in the 390–760 nm, blue light was delayed entirely, and the transmitted red light never exceeded 5 %. Photochemically active radiation passing through the pericarp and coat and reaching the cotyledons at the early and middle seed maturation stages manifested a high proportion of green and far-red light; there was no blue light, and the percentage of red light was about 2 %. However, the cotyledons were photochemically active regardless of low irradiance and spectral ranges untypical of leaf photosynthesis. At the early and middle maturation stages, the maximum quantum yield of photosystem II (Fv/Fm) averaged 0.5 at the periphery of cotyledons and 0.3 at their center. Since the intensity of embryonic photochemical reactions significantly affects the efficiency of reserve nutrient accumulation, this parameter is a promising marker in pea breeding for seeds with improved nutritional qualities.

APA, Harvard, Vancouver, ISO, and other styles

3

Gust, Devens. "Supramolecular photochemistry applied to artificial photosynthesis and molecular logic devices." Faraday Discussions 185 (2015): 9–35. http://dx.doi.org/10.1039/c5fd00142k.

Full text

Abstract:

Supramolecular photochemical systems consist of photochemically active components such as chromophores, electron donors or electron acceptors that are associated via non-covalent or covalent interactions and that interact in some functional way. Examples of interactions are singlet–singlet energy transfer, triplet–triplet energy transfer, photoinduced electron transfer, quantum coherence and spin–spin magnetic interactions. Supramolecular photochemical “devices” may have applications in areas such as solar energy conversion, molecular logic, computation and data storage, biomedicine, sensing, imaging, and displays. This short review illustrates supramolecular photochemistry with examples drawn from artificial photosynthesis, molecular logic, analog photochemical devices and models for avian magnetic orientation.

APA, Harvard, Vancouver, ISO, and other styles

4

M., S. PRASADA RAO, V. L. KUMARI V., SIVA RAO T, and RAMA MOHAN RAO A. "A New Photochemical Redox Method for the Estimation of Thallium(III) in the Presence of High Chloride Ion Concentrations catalysed by Iron(III)." Journal of Indian Chemical Society Vol. 72, Mar 1995 (1995): 185–88. https://doi.org/10.5281/zenodo.5901978.

Full text

Abstract:

Inorganic Chemistry Laboratories, Andhra University, Visakhapatnam-530 003 <em>Manuscript received 7 July 1993, revised 17 November 1993, accepted 23 November 1993</em> A photochemical titrimetric method is described for the determination of thallium(III) with oxalate in 0.5 <em>M</em> perchloric acid and in the presence of high chloride (6.0 mmol) and 0.001-0.002 mmol of iron(m) as catalyst. Thallium(m) is reduced to thallium(I) photochemically with oxalic acid in perchloric acid medium in the presence of excess of chloride using iron(III) as catalyst. The reduced thallium(I) is determined bromatometrically in 1.5-2.0 <em>M</em> HCI in the presence of methyl orange as indicator. The catalytic activity of iron(III) is attributed to its capacity to photochemically oxidise oxalate and the subsequent reaction between thallium(III) and iron(II) in chloride medium. A detailed mechanism is proposed for the catalytic reaction.

APA, Harvard, Vancouver, ISO, and other styles

5

Gan, Chee Yong, John N. Lambert, and Robert W. Gable. "Exploration of the Paternò - Büchi Reaction as a Potential Route to the Oxetan Ring of Taxol®." Australian Journal of Chemistry 52, no. 7 (1999): 629. http://dx.doi.org/10.1071/ch98160.

Full text

Abstract:

Two photochemical pathways to paclitaxel-like oxetan rings have been examined. In the first approach, an intramolecular Paternò–BÜchi reaction on a 6,7-enal was attempted without success. The intermolecular variation using a bicyclic alkene in the presence of either benzaldehyde or acetophenone delivered oxetans whose regiochemistry was the same as that found in paclitaxel but opposite in stereochemistry. The crystal structures of a key intermediate diol and a photochemically generated oxetan are reported.

APA, Harvard, Vancouver, ISO, and other styles

6

Rajakumar, Perumal, Beeran Senthilkumar, and Kannupal Srinivasan. "Synthesis of Azobenzenophanes with a Large Molecular Cavity." Australian Journal of Chemistry 59, no. 1 (2006): 75. http://dx.doi.org/10.1071/ch05254.

Full text

Abstract:

The design and synthesis of four large-cavity azobenzenophanes, capable of forming photochemically controllable complexes with organic guest molecules, are described. These azobenzenophanes, possessing m-terphenyl, aromatic carbonyl, and chiral BINOL spacers, were synthesized from the corresponding bisphenols and dibromides using simple O-alkylation methodology. A preliminary photochemical study was carried out on the aromatic carbonyl spacer containing azobenzenophane, and the isosbestic points for the cis–trans isomerization process appeared at 319 and 419 nm.

APA, Harvard, Vancouver, ISO, and other styles

7

Lang, Kamil, Dana M. Wagnerová, and Jiřina Brodilová. "The Role of Hydrogen Peroxide in Dioxygen Induced Hydroxylation of Salicylic Acid." Collection of Czechoslovak Chemical Communications 59, no. 11 (1994): 2447–53. http://dx.doi.org/10.1135/cccc19942447.

Full text

Abstract:

The photochemically initiated oxidation of salicylic acid by molecular oxygen in the presence of [Fe(C2O4)3]3- leads to a mixture of 2,3- and 2,5-dihydroxybenzoic acids. Iron(II) generated by the photoreduction is reoxidized by dioxygen. Hydrogen peroxide formed in this reaction takes part in the Fenton reaction in the presence of Fe(II). Experiments with OH. radical scavengers document the role of the radicals in the photochemical and thermal hydroxylation of salicylic acid.

APA, Harvard, Vancouver, ISO, and other styles

8

Herbstritt, Domenique, Pooja Tomar, and Thomas Braun. "Activation of SF5CF3 by the N-Heterocyclic Carbene SIMes." Molecules 28, no. 18 (2023): 6693. http://dx.doi.org/10.3390/molecules28186693.

Full text

Abstract:

The greenhouse gas SF5CF3 was photochemically activated with SIMes (1,3-Bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) to give 1,3-dimesityl-2,2-difluoroimidazolidine (SIMesF2), and 1,3-dimesitylimidazolidine-2-sulfide, as well as the trifluoromethylated carbene derivative 1,3-dimesityl-2-fluoro-2-trifluoromethylimidazolidine. CF3 radicals, as well as SF4, serve presumably as intermediates of the conversions. In addition, the photochemical activation of SF5CF3 was performed in the presence of triphenylphosphine. The formation of triphenyldifluorophosphorane and triphenylphosphine sulfide was observed.

APA, Harvard, Vancouver, ISO, and other styles

9

Selyutina, Olga Yu, Viktor A. Timoshnikov, Nikolay E. Polyakov, and George J. Kontoghiorghes. "Metal Complexes of Omadine (N-Hydroxypyridine-2-thione): Differences of Antioxidant and Pro-Oxidant Behavior in Light and Dark Conditions with Possible Toxicity Implications." Molecules 28, no. 10 (2023): 4210. http://dx.doi.org/10.3390/molecules28104210.

Full text

Abstract:

Omadine or N-hydroxypyridine-2-thione and its metal complexes are widely used in medicine and show bactericidal, fungicidal, anticancer, and photochemical activity. The redox activity of omadine complexes with iron, copper, and zinc on lipid peroxidation under light and dark conditions has been investigated. The monitoring of the oxidation of linoleic acid micelles, resembling a model of lipid membrane, was carried out using nuclear magnetic resonance (1H-NMR). It has been shown that the omadine–zinc complex can induce the oxidation of linoleic acid under light irradiation, whereas the complexes with iron and copper are photochemically stable. All the chelating complexes of omadine appear to be redox-inactive in the presence of hydrogen peroxide under dark conditions. These findings suggest that omadine can demonstrate antioxidant behavior in processes involving reactive oxygen species generation induced by transition metals (Fenton and photo-Fenton reactions). However, the omadine complex with zinc, which is widely used in shampoos and ointments, is photochemically active and may cause oxidative cell membrane damage when exposed to light, with possible implications to health.

APA, Harvard, Vancouver, ISO, and other styles

10

Hopf, Henning, Thomas Laue, and Maximilian Zander. "Photochemical and Photophysical Properties of 4- Acyl [2.2] paracyclophanes." Zeitschrift für Naturforschung A 46, no. 9 (1991): 815–18. http://dx.doi.org/10.1515/zna-1991-0911.

Full text

Abstract:

Abstract Photochemical and photophysical properties of 4-benzoyl[2.2]paracyclophane (3) and 4-acetyl[ 2.2]paracyclophane (5) have been studied. In contrast to benzophenone and acetophenone, respectively, the lowest triplet state of 3 and 5 is of the τ, τ*-type. 3 is photochemically reactive. Photoenolization (in solution at lower temperature) is the main reaction pathway while bond fission of an exocyclic C-C bond of the formed photoenol leading to an alkylated open-chain benzophenone derivative takes place to a minor degree. Photoenolization of 3 is the first example of this type of photochemical reaction observed with a cyclophane compound, and at the same time is a novel example of the violation of Bredt's rule. Under certain experimental conditions 3 and 5 may be usable as chiral triplet sensitizers in photochemical reactions

APA, Harvard, Vancouver, ISO, and other styles

11

Cokgor, E. U., I. Arslan-Alaton, E. Erdinc, G. Insel, and D. Orhon. "Effect of photochemical pre-treatment on COD fractionation of a non-ionic textile surfactant." Water Science and Technology 55, no. 10 (2007): 155–63. http://dx.doi.org/10.2166/wst.2007.318.

Full text

Abstract:

The work presented in this paper is focused on the effect of photochemical (H2O2/UV-C) pre-treatment on COD fractionation and degradation kinetics of a non-ionic textile surfactant. In the first part of the study, the COD of non-ionic surfactant was adjusted to 1000 mg/L in order to simulate real effluent originating from the textile preparation stage featuring desizing, scouring, washing and rinsing operations. The surfactant was subjected to H2O2/UV-C pretreatment for up to 120 min at a dose of 30 mM (980 mg/L) H2O2. The biodegradability studies for untreated and photochemically treated samples were evaluated on the basis of modeling of oxygen uptake rate (OUR) profiles. Modelling of OUR profiles conducted for untreated sample showed that single complex substrate was subjected to enzymatic breakdown and disintegrated into one readily and two types of slowly biodegradable substrates. After modelling the biodegradation of photochemically pretreated sample, the readily biodegradable COD fraction was reduced, on the other hand, more slowly biodegradable organics were generated. A higher disintegration rate was obtained for chemically pretreated samples. However, other kinetic constants of growth and hydrolysis processes were not affected considerably.

APA, Harvard, Vancouver, ISO, and other styles

12

Surinder, Berar, Jindal Pooja, Berar Urmila, Bhatia Rimpy, Chaudhary Ashu, and C. Kamboj Ramesh. "Photochemical and thermal transformations of some diallyl-1-benzoylcyclopropanes." Journal of Indian Chemical Society Vol. 91, Dec 2014 (2014): 2271–82. https://doi.org/10.5281/zenodo.5746509.

Full text

Abstract:

Department of Chemistry, Kurukshetra University, Kurukshetra-136 119, Haryana, India <em>E-mail </em>: rckamboj@rediffmail.com <em>Manuscript received online 18 April 2013, revised 12 July 2014, accepted 17 July 2014</em> Photochemical and thermal transformations of diallyl-1-benzoylcyclopropanes to the exotic isomeric alkenes have been described. The products formation is exclusively controlled by the nature of substituents on the cyclopropane ring as well as on the aromatic ring in benzoyl group. The stimulus behind this is the thermostability of the intermediate 1,4-biradical produced photochemically which, in turn, control the product formation/distribution.

APA, Harvard, Vancouver, ISO, and other styles

13

Itoh, S., та S. Onishi. "Kinetic study of the photochemical changes of (ZZ)-bilirubin IX α bound to human serum albumin. Demonstration of (EZ)-bilirubin IX α as an intermediate in photochemical changes from (ZZ)-bilirubin IX α to (EZ)-cyclobilirubin IX α". Biochemical Journal 226, № 1 (1985): 251–58. http://dx.doi.org/10.1042/bj2260251.

Full text

Abstract:

The present study was performed to elucidate why the photochemical reaction of (ZZ)-bilirubin bound to human serum albumin is singularly selective, and only one of the two (EZ)- and (ZE)-bilirubins, the (ZE)-isomer, is produced. In a kinetic study of the photochemical reaction in vitro, the sum of the relative rate constants of photochemical transformation of (EZ)-bilirubin into both (EZ)-cyclobilirubin and (ZZ)-bilirubin, with a significant preference for the former, was proved to be considerably larger than that of the transformation of (ZZ)-bilirubin into (EZ)-bilirubin. Therefore only one of the geometrical isomers, namely (ZE)-bilirubin, is apparently formed. It was concluded that (EZ)-bilirubin photochemically undergoes (EZ)-cyclization, i.e. structural photoisomerization, while bound to its high-affinity site on human serum albumin, and is an intermediate in the transformation of (ZZ)-bilirubin into (EZ)-cyclobilirubin.

APA, Harvard, Vancouver, ISO, and other styles

14

van Drooge, B. L., and J. O. Grimalt. "Particle sized-resolved source apportionment of primary and secondary organic tracer compounds at urban and rural locations in Spain." Atmospheric Chemistry and Physics Discussions 15, no. 7 (2015): 9897–939. http://dx.doi.org/10.5194/acpd-15-9897-2015.

Full text

Abstract:

Abstract. Atmospheric particulate matter (PM) was fractionated in six aerodynamic sizes, > 7.2, 7.2–3, 3–1.5, 1.5–1, 1–0.5, < 0.5 μm, using a cascade impactor. These fractions were collected at urban and rural sites during warm and cold seasons. Analysis of the organic tracer compounds by gas-chromatography coupled to mass-spectrometry showed that the composition in the smallest size fractions (< 0.5 μm) was more uniform than in the larger sizes (7.2 > PM > 0.5 μm). Thus, markers of photochemically synthesized organic compounds or combustion sources, either biomass burning or traffic emissions, were predominantly observed in the fraction < 0.5 μm whereas the larger particles were composed of mixed sources from combustion processes, vegetation emissions, soil re-suspension, road dust, urban life-style activities and photochemically synthesized organic compounds. Important seasonal differences were observed at the rural site. In the < 0.5 μm fraction these were related to strong predominance of biomass burning in the cold period and photochemically transformed biogenic organic compounds in the warm period. In the 7.2 > PM > 0.5 μm fractions the differences involved predominant soil-sourced compounds in the warm period and mixed combustion sources, photochemical products and vegetation emissions in the cold. Multivariate Curve Resolution Alternating Least Squares showed that these organic aerosols essentially originated from six source components. Four of them reflected primary emissions related with either natural products, e.g. vegetation emissions and up whirled soil dust, or anthropogenic contributions, e.g. combustion products and compounds related with urban life-style activities, mainly vehicular exhausts and tobacco smoking. Two secondary organic aerosol components were identified. They accumulated in the smallest (< 0.5 μm) or in the larger fractions (> 0.5 μm) and involved strong or mild photochemical transformations of vegetation precursor molecules, respectively. Toxicologically relevant information was also disclosed with the present approach. Thus, the strong predominance of biomass burning residues at the rural site during the cold period involved atmospheric concentrations of polycyclic aromatic hydrocarbons that were three times higher than at the urban sites and benzo[a]pyrene concentrations above legal recommendations.

APA, Harvard, Vancouver, ISO, and other styles

15

van Drooge, B. L., and J. O. Grimalt. "Particle size-resolved source apportionment of primary and secondary organic tracer compounds at urban and rural locations in Spain." Atmospheric Chemistry and Physics 15, no. 13 (2015): 7735–52. http://dx.doi.org/10.5194/acp-15-7735-2015.

Full text

Abstract:

Abstract. Atmospheric particulate matter (PM) was fractionated in six aerodynamic sizes, > 7.2, 7.2–3, 3–1.5, 1.5–1, 1–0.5 and < 0.5 μm, using a cascade impactor. These fractions were collected at urban and rural sites during warm and cold seasons. Organic tracer compounds, such as levoglucosan, isoprene, pinene oxidation products, polycyclic aromatic hydrocarbons and quinones, were analyzed by gas chromatography coupled with mass spectrometry. These analyses showed that the composition in the smallest size fractions (< 0.5 μm) was more uniform than in the larger sizes (7.2> PM > 0.5 μm). Thus, markers of photochemically synthesized organic compounds or combustion sources, either biomass burning or traffic emissions, were predominantly observed in the fraction < 0.5 μm, whereas the larger particles were composed of mixed sources from combustion processes, vegetation emissions, soil resuspension, road dust, urban lifestyle activities and photochemically synthesized organic compounds. Important seasonal differences were observed at the rural site. In the < 0.5 μm fraction these were related to a strong predominance of biomass burning in the cold period and photochemically transformed biogenic organic compounds in the warm period. In the 7.2 > PM > 0.5 μm fractions the differences involved predominantly soil-sourced compounds in the warm period and mixed combustion sources, photochemical products and vegetation emissions in the cold. Multivariate curve resolution/alternating least squares showed that these organic aerosols essentially originated from six source components. Four of them reflected primary emissions related to either natural products, e.g., vegetation emissions and upwhirled soil dust, or anthropogenic contributions, e.g., combustion products and compounds related to urban lifestyle activities like vehicular exhaust and tobacco smoking. Two secondary organic aerosol components were identified. They accumulated in the smallest (< 0.5 μm) or in the larger fractions (> 0.5 μm) and involved strong or mild photochemical transformations of vegetation precursor molecules, respectively. Toxicologically relevant information was also disclosed with the present approach. Thus, the strong predominance of biomass burning residues at the rural site during the cold period involved atmospheric concentrations of polycyclic aromatic hydrocarbons that were 3 times higher than at the urban sites and benzo[a]pyrene concentrations above legal recommendations.

APA, Harvard, Vancouver, ISO, and other styles

16

Častulík, Jakub, Jaroslav Jonas, and Ctibor Mazal. "Stereoselective 1,3-Dipolar Cycloaddition of a Nitrile Ylide Photochemically Generated from 2,3-Diphenyl-2H-azirine to Substituted Methylene Lactones." Collection of Czechoslovak Chemical Communications 65, no. 5 (2000): 708–16. http://dx.doi.org/10.1135/cccc20000708.

Full text

Abstract:

The nitrile ylide photochemically generated from 2,3-diphenyl-2H-azirine adds to both isomers of 3-(tosyloxymethylene)tetrahydrofuran-2-one with excellent regio- and stereoselectivity giving spiroheterocyclic products in moderate yields. X-Ray structure determination showed dibutolactone to have the E-configuration; the corresponding Z-isomer was prepared photochemically.

APA, Harvard, Vancouver, ISO, and other styles

17

Shinkai, Seiji, Akiko Yoshioka, Hatsumi Nakayama, and Osamu Manabe. "A photochemically activated cyclophane." Journal of the Chemical Society, Perkin Transactions 2, no. 11 (1990): 1905. http://dx.doi.org/10.1039/p29900001905.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Gu, Zhong-Ze, Akira Fujishima, and Osamu Sato. "Photochemically Tunable Colloidal Crystals." Journal of the American Chemical Society 122, no. 49 (2000): 12387–88. http://dx.doi.org/10.1021/ja005595c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Bellelli, Andrea, Maurizio Brunori, Peter Brzezinski, and Michael T. Wilson. "Photochemically Induced Electron Transfer." Methods 24, no. 2 (2001): 139–52. http://dx.doi.org/10.1006/meth.2001.1175.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Cook, Sandra N., William E. Jack, Xiaofeng Xiong, et al. "Photochemically Initiated Protein Splicing." Angewandte Chemie International Edition in English 34, no. 15 (1995): 1629–30. http://dx.doi.org/10.1002/anie.199516291.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Dietrich, W. D., B. D. Watson, R. Busto, M. D. Ginsberg, and J. R. Bethea. "Photochemically induced cerebral infarction." Acta Neuropathologica 72, no. 4 (1987): 315–25. http://dx.doi.org/10.1007/bf00687262.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Dietrich, W. D., R. Busto, B. D. Watson, P. Scheinberg, and M. D. Ginsberg. "Photochemically induced cerebral infarction." Acta Neuropathologica 72, no. 4 (1987): 326–34. http://dx.doi.org/10.1007/bf00687263.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Kamenjicki, M., I. K. Lednev, A. Mikhonin, R. Kesavamoorthy, and S. A. Asher. "Photochemically Controlled Photonic Crystals." Advanced Functional Materials 13, no. 10 (2003): 774–80. http://dx.doi.org/10.1002/adfm.200304424.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Carballosa, Alejandro, Ana I. Gomez-Varela, Carmen Bao-Varela, Maria Teresa Flores-Arias, and Alberto P. Muñuzuri. "Photosensitive Control and Network Synchronization of Chemical Oscillators." Entropy 26, no. 6 (2024): 475. http://dx.doi.org/10.3390/e26060475.

Full text

Abstract:

The Belousov–Zhabotinsky (BZ) reaction has long been a paradigmatic system for studying chemical oscillations. Here, we experimentally studied the synchronization control within photochemically coupled star networks of BZ oscillators. Experiments were carried out in wells performed in soda-lime glass constructed using novel laser technologies. Utilizing the inherent oscillatory nature of the BZ reaction, we engineered a star network of oscillators interconnected through photochemical inhibitory coupling. Furthermore, the experimental setup presented here could be extrapolated to more complex network architectures with both excitatory and inhibitory couplings, contributing to the fundamental understanding of synchronization in complex systems.

APA, Harvard, Vancouver, ISO, and other styles

25

Tian, Hong Yan, Yue Hui Wang, Chun Liu, and Kui Niu. "Preparation, Characterization and Physical Properties of Polyvinyl Alcohol-Layered Clay Nanocomposites." Advanced Materials Research 997 (August 2014): 433–37. http://dx.doi.org/10.4028/www.scientific.net/amr.997.433.

Full text

Abstract:

This work focused on the preparation of poly (vinyl alcohol) (PVA)/ layered double hydroxide (LDH) and LDHSA nanocomposites by casting method. The morphology and interlayer spacing of the composites were characterized. The mechanical properties and the photochemical stability of the film of PVA, PVA/LDH and PVA/LDHSA have been studied and compared with PVA/MMT nanocomposites reported in previously. The results indicated that the thermal stability and dynamic mechanical properties of the PVA matrix in the PVA/LDH films and PVA/MMT films was enhanced. PVA/LDH films and PVA/OMMT films were shown stable photochemically more than those of pure PVA.

APA, Harvard, Vancouver, ISO, and other styles

26

Chen, W. T., M. Shao, S. H. Lu, M. Wang, and L. M. Zeng. "Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model." Atmospheric Chemistry and Physics Discussions 13, no. 6 (2013): 15749–81. http://dx.doi.org/10.5194/acpd-13-15749-2013.

Full text

Abstract:

Abstract. Carbonyls are important intermediates in atmospheric photochemistry. To determine the relative contributions of primary and secondary carbonyl sources in Beijing, carbonyls and other trace gases were measured at Peking University in winter and summer. The Positive Matrix Factorization (PMF) model was used for source apportionment. As volatile organic compounds (VOCs) will undergo photochemical processes in the atmosphere, and such processes may interfere with factors identification, the relationships between the contributions of the resolved PMF factors to each non-methane hydrocarbon (NMHC) species and its kOH value were used to distinguish between photochemically aged factors and fresh factors. As the result of PMF, five factors were resolved in winter, and two of them were identified as sources of photochemically aged emissions. In summer, four factors were resolved, including an aged factor. Carbonyls in the aged factors were simulated by NMHCs consumption and the corresponding carbonyl production yields, and the simulated abundances agreed well with the results obtained by PMF. The source apportionment results indicated that secondary formation was the major source of carbonyls in both seasons, with the contribution of 51.2% and 46.0%. For the three major carbonyl species, primary anthropogenic sources contributed 28.9% and 32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde, 68.1% and 56.2% to acetone in winter and summer, respectively.

APA, Harvard, Vancouver, ISO, and other styles

27

Chen, W. T., M. Shao, S. H. Lu, et al. "Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model." Atmospheric Chemistry and Physics 14, no. 6 (2014): 3047–62. http://dx.doi.org/10.5194/acp-14-3047-2014.

Full text

Abstract:

Abstract. Carbonyl compounds are important intermediates in atmospheric photochemistry. To explore the relative contributions of primary and secondary carbonyl sources, carbonyls and other volatile organic compounds (VOCs) were measured at an urban site in both winter and summer in Beijing. The positive matrix factorization (PMF) model was used for source apportionment of VOCs. As VOCs undergo photochemical processes in the atmosphere, and such processes may interfere with factor identification, the relationships between the contributions of the resolved PMF factors to each non-methane hydrocarbon (NMHC) species and its kOH value were used to distinguish fresh factors and photochemically aged factors. As the result of PMF, five factors were resolved in winter, and two of them were identified as photochemically aged emissions. In summer, four factors were resolved, including one aged factor. Carbonyls abundances from aged factors were simulated by VOCs consumption and the corresponding carbonyl production yields, and the simulated abundances agreed well with the results obtained by the PMF model. The source apportionment results indicated that secondary formation was the major source of carbonyls in both winter and summer, with the respective contributions of 51.2% and 46.0%. For the three major carbonyl species, primary anthropogenic sources contributed 28.9% and 32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde, 68.1% and 56.2% to acetone in winter and summer, respectively.

APA, Harvard, Vancouver, ISO, and other styles

28

McGimpsey, W. G., та J. C. Scaiano. "Photochemistry of α-chloro- and α-bromoacetophenone. Determination of extinction coefficients for halogen–benzene complexes". Canadian Journal of Chemistry 66, № 6 (1988): 1474–78. http://dx.doi.org/10.1139/v88-237.

Full text

Abstract:

The photochemical dehalogenation of α-haloacetophenones (Cl, Br) in benzene solution has been examined under conditions of continuous and pulsed laser irradiation. Product and quantum yield studies indicate that carbon-halogen bond cleavage occurs with quantum yields of 0.88 and 0.41 for α-chloro- and α-bromoacetophenone, respectively. These values are based on trapping studies in which the PhC(O)ĊH2 radicals produced photochemically are scavenged by hydrogen donors such as benzenethiol. Laser flash photolysis studies lead to intense transient signals due to benzene–halogen complexes. Combination of transient data and quantum yields lead to extinction coefficients of 1 800 and 23 700 M−1 cm−1 for the chlorine (490 nm) and bromine (550 nm) complexes, respectively.

APA, Harvard, Vancouver, ISO, and other styles

29

OKUTSU, Tetsuo. "Photochemically Induced Crystallization of Protein." Review of Laser Engineering 43, no. 10 (2015): 694. http://dx.doi.org/10.2184/lsj.43.10_694.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Okutsu, T., K. Furuta, S. Haruta, T. Kuroiwa, and H. Hiratsuka. "Photochemically induced nucleation of protein." Acta Crystallographica Section A Foundations of Crystallography 64, a1 (2008): C48. http://dx.doi.org/10.1107/s0108767308098474.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Wilmsen, C. W. "Characterization of photochemically unpinned GaAs." Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 6, no. 4 (1988): 1180. http://dx.doi.org/10.1116/1.584275.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Marotti, R. "Photoluminescence from photochemically etched silicon." Solar Energy Materials and Solar Cells 76, no. 3 (2003): 263–79. http://dx.doi.org/10.1016/s0927-0248(02)00279-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Pirrung, Michael C., Lara Fallon, Jin Zhu, and Yong Rok Lee. "Photochemically Removable Silyl Protecting Groups." Journal of the American Chemical Society 123, no. 16 (2001): 3638–43. http://dx.doi.org/10.1021/ja002370t.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Squillacote, Michael, James De Felippis, and Ling Lai Yu. "Hydrogenation via photochemically generated diimide." Tetrahedron Letters 34, no. 26 (1993): 4137–40. http://dx.doi.org/10.1016/s0040-4039(00)60511-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Saniabadi, Abby, Kazuo Umemura, Nobuteru Matsumoto, Sadayuki Sakuma, and Mitsuvoshi Nakashima. "phg photochemically induced arterial thrombosis." Japanese Journal of Pharmacology 67 (1995): 278. http://dx.doi.org/10.1016/s0021-5198(19)47077-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Nadji, Sourena, Cheng I. Wang, and John Stephen Taylor. "Photochemically and photoenzymatically cleavable DNA." Journal of the American Chemical Society 114, no. 24 (1992): 9266–69. http://dx.doi.org/10.1021/ja00050a003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Okutsu, Tetsuo. "Photochemically-induced crystallization of protein." Journal of Photochemistry and Photobiology C: Photochemistry Reviews 8, no. 3 (2007): 143–55. http://dx.doi.org/10.1016/j.jphotochemrev.2007.06.002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Pirrung, Michael C., and Yong Rok Lee. "Photochemically-removable silyl protecting groups." Journal of Organic Chemistry 58, no. 25 (1993): 6961–63. http://dx.doi.org/10.1021/jo00077a010.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Ballardini, Roberto, Vincenzo Balzani, Maria Teresa Gandolfi, et al. "A Photochemically Driven Molecular Machine." Angewandte Chemie International Edition in English 32, no. 9 (1993): 1301–3. http://dx.doi.org/10.1002/anie.199313011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Yan, Mingdi. "Photochemically Initiated Single Polymer Immobilization." Chemistry - A European Journal 13, no. 15 (2007): 4138–44. http://dx.doi.org/10.1002/chem.200700317.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Hashem, T. M., M. Zirlewagen, and A. M. Braun. "Simultaneous photochemical generation of ozone in the gas phase and photolysis of aqueous reaction systems using one VUV light source." Water Science and Technology 35, no. 4 (1997): 41–48. http://dx.doi.org/10.2166/wst.1997.0081.

Full text

Abstract:

A more efficient use of vacuum ultraviolet (VUV) radiation produced by an immersed Xe-excimer light source (172 nm) was investigated for the oxidative degradation of organic pollutants in aqueous systems. All emitted VUV radiation from one light source was used in two simultaneous but separate photochemical reactions: (1) photochemical generation of ozone by irradiating oxygen in the gas phase and (2) photolysis of the aqueous reaction system. The gas stream containing the generated ozone is sparged into the reaction system, thus enhancing the oxidative degradation of organic pollutants. The photochemically generated ozone in the gas phase was quantitatively analyzed, and the kinetics of the degradation of 4-chlorophenol (4-CP) and of the dissolved organic carbon (DOC) were determined under different experimental conditions. The results show that the rates of degradation of the substrate and of the DOC decrease in the order of the applied processes, VUV/O3 &gt; O3 &gt; VUV.

APA, Harvard, Vancouver, ISO, and other styles

42

Huang, Y., D. Pagé, D. D. M. Wayner, and P. Mulder. "Radical-induced degradation of a lignin model compound. Decomposition of 1-phenyl-2-phenoxyethanol." Canadian Journal of Chemistry 73, no. 11 (1995): 2079–85. http://dx.doi.org/10.1139/v95-256.

Full text

Abstract:

Reaction of 1-phenyl-2-phenoxyethanol (1) with thermally or photochemically generated tert-butoxyl radicals leads, via the intermediate ketyl radical, to the formation of the corresponding ketone, α-phenoxyacetophenone (4), as the only product at low conversion under an inert atmosphere. An approximately twofold increase in the product yield is observed when the reactions are carried out under oxygen. Under the photochemical conditions it is shown that 4 is the primary product and that acetophenone and phenol are formed as a result of secondary photolysis of 4. These data suggest that the rate constant for fragmentation of the ketyl radical derived from 1 is on the order of 10 s−1 at 298 K and contradict a report in the literature that suggests a rate constant of >106 s−1. The relevance of this study to the photodegradation of lignin and consequent photoyellowing is discussed and a revised mechanism for the photoyellowing of pulp is proposed. Keywords: ketyl radical, photochemical degradation, thermal degradation, lignin.

APA, Harvard, Vancouver, ISO, and other styles

43

Deiana, Marco, Maëlle Mosser, Tangui Le Bahers, et al. "Light-induced in situ chemical activation of a fluorescent probe for monitoring intracellular G-quadruplex structures." Nanoscale 13, no. 32 (2021): 13795–808. http://dx.doi.org/10.1039/d1nr02855c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Yin, Zhen, Huilin He, Zhenming Wang, et al. "Facile In Situ Photochemical Synthesis of Silver Nanoaggregates for Surface-Enhanced Raman Scattering Applications." Nanomaterials 10, no. 4 (2020): 685. http://dx.doi.org/10.3390/nano10040685.

Full text

Abstract:

Recently, photochemical synthesis has attracted wide interest on in situ preparing the surface-enhanced Raman scattering (SERS) substrate with excellent performance, especially in a compact space and microfluidic channel. Herein, a facile, green and cost-effective approach to in situ photochemically synthesize silver nanoaggregates is demonstrated for SERS applications. By adjusting the photo-irradiation conditions, the morphologies and sizes of the silver nanoaggregates can be deliberately tailored. The synthesized silver nanoaggregates-based substrates exhibit a highly sensitive and reproducible SERS activity with a low detection limit of 10−8 M for 4-Aminothiophenol detection and relative standard deviation of 12.3%, paving an efficient and promising route for in situ SERS-based rapid detection in the environmental monitoring and food quality control.

APA, Harvard, Vancouver, ISO, and other styles

45

Ogawa, M., M. Hama, and K. Kuroda. "Photochromism of azobenzene in the hydrophobic interlayer spaces of dialkyldimethylammonium-fluor-tetrasilicic mica films." Clay Minerals 34, no. 2 (1999): 213–20. http://dx.doi.org/10.1180/000985599546127.

Full text

Abstract:

AbstractPhotochemical isomerization of azobenzene intercalated in the hydrophobic, interlayer spaces of swelling fluor-tetrasilicic micas exchanged with dialkyldimethylammonium ions, with the alkyl chain length from 10 to 18, was investigated. Thin films of the organoammonium-mica-azobenzene intercalation compounds were obtained by depositing a suspension of the organoammonium-micas (prepared using a toluene/methanol solution of azobenzene) on quartz substrates. The intercalated azobenzene showed reversible photochromic reactions induced by UV and visible light irradiation. The fraction of the photochemically formed cis-isomer in the photostationary states decreased with a decrease in temperature. The observed change in the photochemical reactions is thought to reflect changes in the states of the dialkyldimethylammonium ions in the interlayer space of the swelling fluor-tetrasilicic mica.

APA, Harvard, Vancouver, ISO, and other styles

46

Tian, Na-na, Chao Li, Na Tian, et al. "Syntheses of 7-dehydrocholesterol peroxides and their improved anticancer activity and selectivity over ergosterol peroxide." New Journal of Chemistry 41, no. 24 (2017): 14843–46. http://dx.doi.org/10.1039/c7nj04100d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Netto-Ferreira, José Carlos, Virginie Lhiaubet-Vallet, Bauer Bernardes, Aurelio Baird Buarque Ferreira та Miguel Ángel Miranda. "Photophysics and photochemistry of the β-lapachone derived diphenyldihydrodioxin: generation and characterization of its cation radical". Photochem. Photobiol. Sci. 13, № 12 (2014): 1655–60. http://dx.doi.org/10.1039/c4pp00231h.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Morris, Jason, Sofia Telitel, Kathryn E. Fairfull-Smith, et al. "Novel polymer synthesis methodologies using combinations of thermally- and photochemically-induced nitroxide mediated polymerization." Polymer Chemistry 6, no. 5 (2015): 754–63. http://dx.doi.org/10.1039/c4py01270d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Wenska, Grazyna, Bohdan Skalski, Stefan Paszyc, and Zofia Gdaniec. "Photochemistry of N-(pyrimidin-2-one-4-yl)pyridinium derivatives. The ring contraction of pyrimidinone into imidazolinone." Canadian Journal of Chemistry 73, no. 12 (1995): 2178–84. http://dx.doi.org/10.1139/v95-270.

Full text

Abstract:

Photochemical reactions (λ > 300 nm) of N-(1-methylpyrimidin-2-one)-and N-(1,5-dimethyl-pyrimidin-2-one)pyridinium chlorides were studied in deoxygenated aqueous solution at various pH's. Only the former compound was found to be reactive under these conditions to give pyrimidine ring contraction photoproducts 1-methyl-4-imidazolin-2-one and 1-methyl-4-imidazolin-2-one-5-carboxyaldehyde, with pH-dependent chemical yields. The photochemical pyrimidine ring contraction reaction does not occur for other photochemically reactive pyrimidin-2-ones bearing 3-methylimidazolium-1,1,2,4-triazol-1-yl, or imidazol-1-yl as substituents at the C-4 position. The suggested mechanism of the reaction involves the addition of water to the pyrimidinone part of the N-(1-methylpyrimidin-2-one)pyridinium salt in the excited triplet state as the primary photochemical step. Addition of alcohol to the pyridinium ring was found to be the major reaction under irradiation of N-(1-methylpyrimidin-2-one-4-yl)pyridinium chloride in methanol. Keywords: photochemistry, N-(pyrimidin-2-one-4-yl)pyridinium compounds, pyrimidine ring contraction, 1-substituted-4-imidazolin-2-ones, 4-imidazolin-2-one-5-carboxyaldehydes.

APA, Harvard, Vancouver, ISO, and other styles

50

Kaya, Kerem, Tapas Debsharma, Helmut Schlaad, and Yusuf Yagci. "Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether." Polymer Chemistry 11, no. 43 (2020): 6884–89. http://dx.doi.org/10.1039/d0py01307b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!