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Molecules (Basel, Switzerland) Sep 2019Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous... (Review)
Review
Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.
Topics: Biodegradation, Environmental; Catalysis; Environmental Pollutants; Oxidation-Reduction; Photolysis; Ultrasonic Waves
PubMed: 31540329
DOI: 10.3390/molecules24183341 -
Molecules (Basel, Switzerland) Dec 2020Photocatalysis emerged in the last decades as a versatile technology, whose applications range from environmental remediation to hydrogen production, energy harvesting,...
Photocatalysis emerged in the last decades as a versatile technology, whose applications range from environmental remediation to hydrogen production, energy harvesting, and organic synthesis, with exciting examples also in medicine, electronics, and advanced functional materials [...].
Topics: Catalysis; Electronics; Environmental Restoration and Remediation; Photolysis; Polymers
PubMed: 33374553
DOI: 10.3390/molecules26010023 -
Molecules (Basel, Switzerland) Nov 2020Photocages have been successfully applied in cellular signaling studies for the controlled release of metabolites with high spatio-temporal resolution. Commonly,...
Photocages have been successfully applied in cellular signaling studies for the controlled release of metabolites with high spatio-temporal resolution. Commonly, coumarin photocages are activated by UV light and the quantum yields of uncaging are relatively low, which can limit their applications in vivo. Here, syntheses, the determination of the photophysical properties, and quantum chemical calculations of 7-diethylamino-4-hydroxymethyl-thiocoumarin (thio-DEACM) and caged adenine nucleotides are reported and compared to the widely used 7-diethylamino-4-hydroxymethyl-coumarin (DEACM) caging group. In this comparison, thio-DEACM stands out as a phosphate cage with improved photophysical properties, such as red-shifted absorption and significantly faster photolysis kinetics.
Topics: Adenosine Triphosphate; Coumarins; Fluorescence; Light; Nucleotides; Photolysis; Physical Phenomena
PubMed: 33203096
DOI: 10.3390/molecules25225325 -
Nature Methods Oct 2018
Topics: Fluorescence; HeLa Cells; Humans; Microscopy, Fluorescence; Oxidation-Reduction; Photochemical Processes; Photolysis
PubMed: 30275592
DOI: 10.1038/s41592-018-0145-5 -
British Journal of Pharmacology Aug 19961. We studied the effects of flash photolysis on the novel enantiomeric cardiac inotropes EMD 57033 (a calcium sensitizer) and EMD 57439 (a phosphodiesterase III...
1. We studied the effects of flash photolysis on the novel enantiomeric cardiac inotropes EMD 57033 (a calcium sensitizer) and EMD 57439 (a phosphodiesterase III inhibitor) in rat isolated ventricular trabeculae. 2. In skinned trabeculae, EMD 57439 had no effect on force production, consistent with lack of an active cyclic AMP system in this preparation. In contrast, EMD 57033 potentiated force at partial and maximal activation. A single flash of near u.v. light given at partial activation (30-70%) reduced force potentiation by 52.4 +/- 5.2%. No effect was produced by flashes in the presence of EMD 57439 or in the absence of either drug. 3. The time course of relaxation induced by EMD 57033 photolysis was indistinguishable from that obtained on deactivating the muscle by rapidly lowering Ca2+ using photolysis of the caged chelator of calcium, diazo-2. 4. In intact, twitching trabeculae, EMD 57033 increased diastolic and peak force and slowed relaxation. These effects were simultaneously reduced by a light flash. In these muscles EMD 57439 reduced force, without affecting the twitch time course. These effects were also reduced by a light flash. 5. The u.v. absorbance spectra of EMD 57033 and EMD 57439 were identical. After photolysis optical density decreased substantially and the peak shifted from 320 nm to 280 nm. 6. The proton n.m.r. spectra of these compounds were identical. The main change post-photolysis was a decrease in the proton signal associated with the enantiomeric carbon atom. 7. This novel manipulation of the molecular structure of EMD 57033 and EMD 57439 within an experiment thus provides direct evidence linking calcium sensitization to a particular molecular structure. The three main effects of the sensitizer on the twitch were simultaneously abolished and may be mechanistically linked. Flash photolysis may be a useful tool for further investigations of the actions of these compounds. In particular, flash photolysis of the sensitizer represents a novel method of rapidly deactivating cardiac muscle.
Topics: Animals; Calcium; Male; Phosphodiesterase Inhibitors; Photolysis; Quinolines; Rats; Rats, Wistar; Thiadiazines
PubMed: 8864540
DOI: 10.1111/j.1476-5381.1996.tb15641.x -
International Journal of Molecular... Apr 2021Photodegradation of the aqueous solutions of acetylsalicylic acid, in the absence (ASA) and the presence of excipients (ASE), is demonstrated by the photoluminescence...
Photodegradation of the aqueous solutions of acetylsalicylic acid, in the absence (ASA) and the presence of excipients (ASE), is demonstrated by the photoluminescence (PL). A shift of the PL bands from 342 and 338 nm to 358 and 361-397 nm for ASA and ASE in solid state and as aqueous solutions was reported. By exposure of the solution of ASA 0.3 M to UV light, a decrease in the PL band intensity was highlighted. This behavior was revealed for ASA in the presence of phosphate buffer (PB) having the pH equal to 6.4, 7, and 8 or by the interaction with NaOH 0.3 M. A different behavior was reported in the case of ASE. In the presence of PB, an increase in the intensity of the PL band of ASE simultaneously with a change of the ratio between the intensities of the bands at 361-364 and 394-397 nm was highlighted. The differences between PL spectra of ASA and ASE have their origin in the presence of salicylic acid (SAL). The interaction of ASE with NaOH induces a shift of the PL band at 405-407 nm. Arguments for the reaction of ASA with NaOH are shown by Raman scattering and FTIR spectroscopy.
Topics: Aspirin; Cadmium Compounds; Luminescence; Photolysis; Quantum Dots; Solutions; Spectrum Analysis, Raman; Ultraviolet Rays; Water
PubMed: 33919943
DOI: 10.3390/ijms22084046 -
Molecules (Basel, Switzerland) Dec 2019The APEX (aqueous photochemistry of environmentally occurring xenobiotics) software computes the phototransformation kinetics of compounds that occur in sunlit surface... (Review)
Review
A Critical View of the Application of the APEX Software (Aqueous Photochemistry of Environmentally-Occurring Xenobiotics) to Predict Photoreaction Kinetics in Surface Freshwaters.
The APEX (aqueous photochemistry of environmentally occurring xenobiotics) software computes the phototransformation kinetics of compounds that occur in sunlit surface waters. It is free software based on Octave, and was originally released in 2014. Since then, APEX has proven to be a remarkably flexible platform, allowing for the addressing of several environmental problems. However, considering APEX as a stand-alone software is not conducive to exploiting its full potentialities. Rather, it is part of a whole ecosystem that encompasses both the software and the laboratory protocols that allow for the measurement of substrate photoreactivity parameters. Coherently with this viewpoint, the present paper shows both how to use APEX, and how to experimentally derive or approximately assess the needed input data. Attention is also given to some issues that might provide obstacles to users, including the extension of APEX beyond the simple systems for which it was initially conceived. In particular, we show how to use APEX to deal with compounds that undergo acid-base equilibria, and with the photochemistry of systems such as stratified lakes, lakes undergoing evaporation, and rivers. Hopefully, this work will provide a reference for the smooth use of one of the most powerful instruments for the modeling of photochemical processes in freshwater environments.
Topics: Algorithms; Cheminformatics; Fresh Water; Models, Chemical; Photochemical Processes; Photolysis; Software; Sunlight; Xenobiotics
PubMed: 31861417
DOI: 10.3390/molecules25010009 -
Molecules (Basel, Switzerland) Dec 2018Chloro- and dichloro-methylsulfonyl nitrenes, CH₂ClS(O)₂N and CHCl₂S(O)₂N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding...
Chloro- and dichloro-methylsulfonyl nitrenes, CH₂ClS(O)₂N and CHCl₂S(O)₂N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH₂ClS(O)₂N₃ and CHCl₂S(O)₂N₃, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N₂ (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH₂ClS(O)₂N (|/| = 1.57 cm and |/| = 0.0026 cm) and CHCl₂S(O)₂N (|/| = 1.56 cm and |/| = 0.0042 cm) has been confirmed. In addition, dichloromethylnitrene CHCl₂N (|/| = 1.57 cm and |/| = 0 cm), formed from SO₂-elimination in CHCl₂S(O)₂N, has also been identified for the first time. Upon UV light irradiation (365 nm), the two sulfonyl nitrenes R⁻S(O)₂N (R = CH₂Cl and CHCl₂) undergo concomitant 1,2-R shift to -sulfonlyamines R⁻NSO₂ and 1,2-oxygen shift to -nitroso compounds R⁻S(O)NO, respectively. The identification of these new species with IR spectroscopy is supported by N labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level. In contrast, the thermally-generated sulfonyl nitrenes CH₂ClS(O)₂N (600 K) and CHCl₂S(O)₂N (700 K) dissociate completely in the gas phase, and in both cases, HCN, SO₂, HCl, HNSO, and CO form. Additionally, ClCN, OCCl₂, HNSO₂, •NSO₂, and the atmospherically relevant radical •CHCl₂ are also identified among the fragmentation products of CHCl₂S(O)₂N. The underlying mechanisms for the rearrangement and decomposition of CH₂ClS(O)₂N and CHCl₂S(O)₂N are discussed based on the experimentally-observed products and the calculated potential energy profile.
Topics: Electron Spin Resonance Spectroscopy; Isomerism; Light; Nitroso Compounds; Photolysis; Quantum Theory; Spectrophotometry, Infrared; Spectrum Analysis; Temperature
PubMed: 30551679
DOI: 10.3390/molecules23123312 -
International Journal of Environmental... Aug 2022The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters' personal protective equipment is a concern. One form of preventing from these compounds is to...
The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters' personal protective equipment is a concern. One form of preventing from these compounds is to decontaminate proximity firefighting protective clothing (PFPC). Traditional decontamination methods do not promote total removal of pollutants and alter the properties of PFPC. The objective of this work was to evaluate the effectiveness of white light-photolysis (WLP), an advanced oxidation process (AOP), for removing PAHs from PFPC, while maintaining the integrity of the fabric fibers. Experiments were carried out, varying reaction time and concentration of HO. With WLP (without HO), it was possible to remove more than 73% of the PAHs tested from the outer layer of PFPC in 3 days. The WLP provided the greatest removal of PAHs, compared with the most common mechanical decontamination techniques (laundering and wet-soap brushing). The fibers' integrity after exposure to the white light was evaluated with infrared spectroscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. In addition, a tearing strength test was performed. No remarkable fabric degradation was observed, indicating a possible, routine-compatible, simple, and inexpensive method of decontamination of PFPC, based on photolysis, which is effective in the degradation of PAHs and maintains the integrity of fabric fibers.
Topics: Air Pollutants, Occupational; Firefighters; Fires; Hydrogen Peroxide; Occupational Exposure; Photolysis; Polycyclic Aromatic Hydrocarbons; Protective Clothing
PubMed: 36011697
DOI: 10.3390/ijerph191610054 -
Proceedings of the National Academy of... Nov 1978Pheomelanin, the red-brown polymeric pigment in the skin and hair of red-headed humans, is composed of a protein fraction covalently bound to a colored chromophore....
Pheomelanin, the red-brown polymeric pigment in the skin and hair of red-headed humans, is composed of a protein fraction covalently bound to a colored chromophore. Photolysis of aerated aqueous phemelanin solutions, isolated from human red hair, results in destruction of the chromophore and liberation of the peptide fraction. The rate of photolysis depends on the pH and the concentration of both pigment and oxygen and is slightly inhibited by the enzyme superoxide dismutase (superoxide:superoxide oxidoreductase EC 1.15.1.1). Pheomelanin photolyzed in the presence of nitroblue tetrazolium results in the formation of a blue diformazan, whether or not oxygen is present. Superoxide dismutase inhibits the aerobic photoreduction of nitroblue tetrazolium whereas, in the absence of oxygen, no inhibition is observed. These experiments strongly suggest the involvement of superoxide in the aerobic photolysis of pheomelanin and point out a possible mechanism for ultraviolet-induced cell damage in redheads.
Topics: Amino Acids; Hair; Humans; Kinetics; Melanins; Oxygen Consumption; Photolysis; Superoxide Dismutase
PubMed: 281688
DOI: 10.1073/pnas.75.11.5395