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Chlorine reactivity

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https://www.readbyqxmd.com/read/28541663/mechanistic-insight-into-the-reactivity-of-chlorine-derived-radicals-in-the-aqueous-phase-uv-chlorine-advanced-oxidation-process-quantum-mechanical-calculations
#1
Daisuke Minakata, Divya Kamath, Shaye Maetzold
The combined ultraviolet (UV) and free chlorine (UV/chlorine) advanced oxidation process that produces highly reactive hydroxyl radicals (HO•) and chlorine radicals (Cl•) is an attractive alternative to UV alone or chlorination for disinfection because of the destruction of a wide variety of organic compounds. However, concerns about the potential formation of chlorinated transformation products require an understanding of the radical-induced elementary reaction mechanisms and their reaction rate constants...
May 25, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28537894/intratumoral-depletion-of-regulatory-t-cells-using-cd25-targeted-photodynamic-therapy-in-a-mouse-melanoma-model-induces-antitumoral-immune-responses
#2
Dong Sun Oh, Heegon Kim, Ji Eun Oh, Hi Eun Jung, Yun Soo Lee, Ji-Ho Park, Heung Kyu Lee
Tumor immunotherapy aims to overcome the immunosuppressive microenvironment within tumors, and various approaches have been developed. Tumor-associated T regulatory cells (Tregs) suppress the activation and expansion of tumor antigen-specific effector T cells, thus, providing a permissive environment for tumor growth. Therefore, optimal strategies need to be established to deplete tumor-infiltrated Tregs because systemic depletion of Tregs can result in reduced anti-tumor effector cells and autoimmunity. Here, to selectively deplete Tregs in tumors, we intratumorally injected anti-CD25 antibodies conjugated to Chlorin e6 (Ce6), a photosensitizer that absorbs light to generate reactive oxygen species...
May 7, 2017: Oncotarget
https://www.readbyqxmd.com/read/28527979/degradation-of-chloramphenicol-by-uv-chlorine-treatment-kinetics-mechanism-and-enhanced-formation-of-halonitromethanes
#3
Huiyu Dong, Zhimin Qiang, Jun Hu, Jiuhui Qu
Ultraviolet (UV)/chlorine process is considered as an emerging advanced oxidation process for the degradation of micropollutants. This study investigated the degradation of chloramphenicol (CAP) and formation of disinfection by-products (DBPs) during the UV/chlorine treatment. It was found that CAP degradation was enhanced by combined UV/chlorine treatment compared to that of UV and chlorination treatment alone. The pseudo-first-order rate constant of the UV/chlorine process at pH 7.0 reached 0.016 s(-1), which was 10...
May 17, 2017: Water Research
https://www.readbyqxmd.com/read/28527415/trace-bromide-ion-impurity-leads-to-formation-of-chlorobromoaromatic-by-products-in-peroxymonosulfate-based-oxidation-of-chlorophenols
#4
Changling Fang, Zhaohui Wang, Min Feng, Ying Huang, Fei Yang, Jianshe Liu
Trace bromide (Br(-)) released from industrial effluents or brominated compounds is able to directly react with peroxymonosulfate (PMS) to generate a series of reactive oxidants which can oxidize and also halogenate organics. We report the identification and evolution of by-products during 2,4,6-trichlorophenol (TCP) degradation in the presence of PMS and trace Br(-). The influencing factors, including Br(-) concentration and pH, were investigated. The depletion of TCP was accelerated with increasing trace Br(-) concentration (0-0...
May 15, 2017: Chemosphere
https://www.readbyqxmd.com/read/28508904/chloride-accelerated-cu-fenton-chemistry-for-biofilm-removal
#5
Li Wang, Yanni Miao, Mingsheng Lu, Zhi Shan, Shan Lu, Jiaojiao Hou, Qiumei Yang, Xinle Liang, Tao Zhou, Dennis Curry, Ken Oakes, Xu Zhang
Biofilms present challenges to numerous industries. Herein, a simple approach was developed based on chloride-accelerated Fenton chemistry, where copper oxide nanoparticles facilitate efficient generation of reactive chlorine species for biofilm removal.
May 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28503718/photodithazine-photodynamic-effect-on-viability-of-9l-lacz-gliosarcoma-cell-line
#6
Leticia C Fontana, Juliana G Pinto, André H C Pereira, Cristina P Soares, Leandro J Raniero, Juliana Ferreira-Strixino
Even with the advances of conventional treatment techniques, the nervous system cancer prognosis is still not favorable to the patient which makes alternative therapies needed to be studied. Photodynamic therapy (PDT) is presented as a promising therapy, which employs a photosensitive (PS) agent, light wavelength suitable for the PS agent, and molecular oxygen, producing reactive oxygen species in order to induce cell death. The aim of this study is to observe the PDT action in gliosarcoma cell using a chlorin (Photodithazine, PDZ)...
May 15, 2017: Lasers in Medical Science
https://www.readbyqxmd.com/read/28502228/the-toxic-effects-of-polychlorinated-biphenyl-aroclor-1242-on-tm3-leydig-cells
#7
Yasemin Aydin, Melike Erkan
Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disrupt endocrine function in biological systems, especially in the male reproductive system. Previous studies on the reproductive toxicity of PCBs have focused on the impairment of spermatogenesis, disruption of steroidogenesis, decreased sperm number, and infertility. Aroclor 1242 is a commercial mixture with an average of 42% chlorine by weight. The purpose of the present study was to elucidate the hazardous effects of Aroclor 1242 on Leydig cells through an evaluation of cell viability, lipid peroxidation, hydroxyl radicals, H2O2 production, antioxidant enzymes, and steroidogenic enzymes...
January 1, 2017: Toxicology and Industrial Health
https://www.readbyqxmd.com/read/28501147/a-fluorescent-homogeneous-assay-for-myeloperoxidase-measurement-in-biological-samples-a-positive-correlation-between-myeloperoxidase-generated-hocl-level-and-oxidative-status-in-stz-diabetic-rats
#8
Pierre Stocker, Mathieu Cassien, Nicolas Vidal, Sophie Thétiot-Laurent, Sylvia Pietri
Myeloperoxidase (MPO) is a key enzyme derived from leukocytes which is associated with the initiation and progression of many inflammatory diseases. Increased levels of MPO may contribute to cellular dysfunction and tissues injury by producing highly reactive oxidants such as hypochlorous acid (HOCl). Myeloperoxidase-generated HOCl is therefore considered as a relevant biomarker of oxidative stress-related damage and its quantitation is of great importance to the study of disease progression. In this context, the current study describes a rapid, sensitive and homogeneous fluorescence-based method for detecting the MPO chlorination activity in biological samples...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28501015/effect-of-medium-pressure-uv-lamp-treatment-on-disinfection-by-products-in-chlorinated-seawater-swimming-pool-waters
#9
Waqas A Cheema, Tarek Manasfi, Kamilla M S Kaarsholm, Henrik R Andersen, Jean-Luc Boudenne
Several brominated disinfection by-products (DBPs) are formed in chlorinated seawater pools, due to the high concentration of bromide in seawater. UV irradiation is increasingly employed in freshwater pools, because UV treatment photodegrades harmful chloramines. However, in freshwater pools it has been reported that post-UV chlorination promotes the formation of other DBPs. To date, UV-based processes have not been investigated for DBPs in seawater pools. In this study, the effects of UV, followed by chlorination, on the concentration of three groups of DBPs were investigated in laboratory batch experiments using a medium-pressure UV lamp...
May 10, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28500968/stability-and-removal-of-selected-avobenzone-s-chlorination-products
#10
Cheng Wang, Mojca Bavcon Kralj, Berta Košmrlj, Jun Yao, Suzana Košenina, Olga V Polyakova, Viatcheslav B Artaev, Albert T Lebedev, Polonca Trebše
Stability studies of two avobenzone transformation products: chloro-avobenzone [2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] and dichloro-avobenzone [2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] have been performed at different pHs values as well as under UV A light and compared with the stability of avobenzone, one of the mostly used UV A filter present in sunscreens. We have additionally investigated the possibility of application of TiO2 photocatalysis as a method for the removal of them...
May 6, 2017: Chemosphere
https://www.readbyqxmd.com/read/28499825/induction-of-cytochrome-p450-dependent-mixed-function-oxidase-activities-and-peroxisome-proliferation-by-chloramine-t-in-male-rat-liver
#11
María-Aránzazu Martínez, Irma Ares, Jose-Luís Rodríguez, Marta Martínez, María-Rosa Martínez-Larrañaga, Arturo Anadón
Chloramine-T is an antimicrobial agent recognized for its disinfectant properties widely used in food industry. As an N-chloro-compound, chloramine-T contains electrophilic chlorine and in water it hydrolyses to hypochlorite. Chlorine as hypochlorous acid or hypochlorite is a very reactive chemical which can function as both an oxidant and halogenating agent. Because chloramine-T could be involved in the metabolic activation of drugs, in the present study the effects of chloramine-T on the activities of some drug metabolizing enzymes in rat liver microsomes and peroxisome proliferation were determined in vivo...
May 9, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/28488466/the-removal-of-chlorinated-aliphatic-hydrocarbons-from-water-using-reactive-activated-carbon-the-influence-of-synthesis-factors-and-reaction-environments
#12
Zhang Wei, Xiao Ting, Liu Nuo, Ying Weichi
In this work, granular activated carbon composite incorporated with nanoscale zerovalent iron particles (reactive activated carbon, RAC) was synthesized by the liquid phase precipitation method and used to remove chlorinated aliphatic hydrocarbons (CAHs) from water. The influence of synthesis factors, such as base carbon types and annealing treatment temperature, and environmental factors, such as molecular structure of CAHs, common ionic species and natural organic matter, on the removal capacities of RAC for CAHs were investigated...
May 10, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28463731/effect-of-oxidant-demand-on-the-release-and-degradation-of-microcystin-lr-from-microcystis-aeruginosa-during-oxidation
#13
Haiting Zhang, Yongbo Dan, Craig D Adams, Honglan Shi, Yinfa Ma, Todd Eichholz
In this research, the release and degradation of intracellular microcystin-LR (MC-LR) due to oxidation of Microcystis aeruginosa (M. aeruginosa) was examined kinetically. Brief exposure to free chlorine with no measureable oxidant exposure was demonstrated to be sufficient to induce rapid release of intracellular MC-LR from M. aeruginosa. Thus, in a water treatment plant, there is currently no level of prechlorination that can be assumed to be safe, since very low preoxidation prior to filtration and no measureable free chlorine residual may still observe the release and buildup of extracellular MC-LR...
April 24, 2017: Chemosphere
https://www.readbyqxmd.com/read/28458215/transformation-of-iodide-and-formation-of-iodinated-by-products-in-heat-activated-persulfate-oxidation-process
#14
Lu Wang, Deyang Kong, Yuefei Ji, Junhe Lu, Xiaoming Yin, Quansuo Zhou
Formation of halogenated disinfection by-products (DBPs) in sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted considerable concerns recently. Previous studies have focused on the formation of chlorinated and brominated DBPs. This research examined the transformation of I(-) in heat activated PS oxidation process. Phenol was employed as a model compound to mimic the reactivity of dissolved natural organic matter (NOM) toward halogenation. It was found that I(-) was transformed to free iodine which attacked phenol subsequently leading to iodinated DBPs such as iodoform and iodoacetic acids...
April 19, 2017: Chemosphere
https://www.readbyqxmd.com/read/28451165/highly-planar-diarylamine-fused-porphyrins-and-their-remarkably-stable-radical-cations
#15
Norihito Fukui, Wonhee Cha, Daiki Shimizu, Juwon Oh, Ko Furukawa, Hideki Yorimitsu, Dongho Kim, Atsuhiro Osuka
Oxidative fusion reactions of meso-phenoxazino Ni(ii) porphyrin were found to be temperature dependent, giving rise to either a doubly phenylene-fused product at room temperature or a singly phenoxazine-fused product at 70 °C. The latter was further oxidized to a doubly phenoxazine-fused Ni(ii) porphyrin, which was subsequently converted to the corresponding free base porphyrin and Zn(ii) porphyrin. Compared to previously reported diphenylamine-fused porphyrins that displayed a molecular twist, doubly phenoxazine-fused porphyrins exhibited distinctly different properties owing to their highly planar structures, such as larger fluorescence quantum yields, formation of an offset face-to-face dimer both in solution and the solid state, and the generation of a mixed-valence π-radical cation dimer upon electrochemical oxidation...
January 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28437627/tumor-acidity-activatable-tat-targeted-nanomedicine-for-enlarged-fluorescence-magnetic-resonance-imaging-guided-photodynamic-therapy
#16
Meng Gao, Feng Fan, Dongdong Li, Yue Yu, Kuirong Mao, Tianmeng Sun, Haisheng Qian, Wei Tao, Xianzhu Yang
Nanoparticles simultaneously integrated the photosensitizers and diagnostic agents represent an emerging approach for imaging-guided photodynamic therapy (PDT). However, the diagnostic sensitivity and therapeutic efficacy of nanoparticles as well as the heterogeneity of tumors pose tremendous challenges for clinical imaging-guided PDT treatment. Herein, a polymeric nanoparticle with tumor acidity (pHe)-activatable TAT targeting ligand that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates contrast agent Gd(3+) is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT...
April 18, 2017: Biomaterials
https://www.readbyqxmd.com/read/28435466/design-of-tumor-acidity-responsive-sheddable-nanoparticles-for-fluorescence-magnetic-resonance-imaging-guided-photodynamic-therapy
#17
Feng Fan, Yue Yu, Fei Zhong, Meng Gao, Tianmeng Sun, Jiaxin Liu, Huimao Zhang, Haisheng Qian, Wei Tao, Xianzhu Yang
Imaging-guided cancer therapy, which integrates diagnostic and therapeutic functionalities into a single system, holds great promise to enhance the accuracy of diagnosis and improve the efficacy of therapy. Specifically, for photodynamic therapy (PDT), it is highly desirable to precisely focus laser light onto the tumor areas to generate reactive oxygen species (ROS) that are cytotoxic tumor cells and avoid light-associated side effects. Herein, a distinct three-layer nanostructured particle with tumor acidity-responsiveness (S-NP) that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates Gd(3+) is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT...
2017: Theranostics
https://www.readbyqxmd.com/read/28420885/oxidative-stress-protein-damage-and-repair-in-bacteria
#18
REVIEW
Benjamin Ezraty, Alexandra Gennaris, Frédéric Barras, Jean-François Collet
Oxidative damage can have a devastating effect on the structure and activity of proteins, and may even lead to cell death. The sulfur-containing amino acids cysteine and methionine are particularly susceptible to reactive oxygen species (ROS) and reactive chlorine species (RCS), which can damage proteins. In this Review, we discuss our current understanding of the reducing systems that enable bacteria to repair oxidatively damaged cysteine and methionine residues in the cytoplasm and in the bacterial cell envelope...
April 19, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28418706/radiation-driven-formation-of-reactive-oxygen-species-in-oxychlorine-containing-mars-surface-analogues
#19
Christos D Georgiou, Dimitrios Zisimopoulos, Electra Kalaitzopoulou, Richard C Quinn
The present study demonstrates that γ-radiolyzed perchlorate-containing Mars soil salt analogues (in a CO2 atmosphere) generate upon H2O wetting the reactive oxygen species (ROS) superoxide radical (O2(•-)), hydrogen peroxide (H2O2), and hydroxyl radicals ((•)OH). This study also validates that analogue radiolysis forms oxychlorine species that, in turn, can UV-photolyze to (•)OH upon UV photolysis. This investigation was made possible by the development of a new assay for inorganic-origin O2(•-) and H2O2 determination and by the modification of a previous assay for soil (•)OH...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28418689/an-official-american-thoracic-society-workshop-report-chemical-inhalational-disasters-biology-of-lung-injury-development-of-novel-therapeutics-and-medical-preparedness
#20
Eleanor M Summerhill, Gary W Hoyle, Sven-Eric Jordt, Bronwen J Jugg, James G Martin, Sadis Matalon, Steven E Patterson, David J Prezant, Alfred M Sciuto, Erik R Svendsen, Carl W White, Livia A Veress
This report is based upon the proceedings from the Inhalational Lung Injury Workshop jointly sponsored by the American Thoracic Society (ATS) and the National Institute of Health (NIH)/National Institute of Neurologic Disorders and Stroke (NINDS) Countermeasures Against Chemical Threats (CounterACT) program on May 21, 2013 in Philadelphia, PA. The CounterACT program facilitates research leading to the development of new and improved medical countermeasures for chemical threat agents. The workshop was initiated by the Terrorism and Inhalational Disasters (TID) Section of the Environmental, Occupational, and Population Health Assembly (EOPH) of the ATS...
April 18, 2017: Annals of the American Thoracic Society
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