Understanding of enhanced nitrate in fine particles at agricultural sites in summer with high ammonia level.

Nitrate is one of the major constituents of fine particles and has not been effectively alleviated in Northeast Asia. Field measurements of various gases and the chemical composition of fine particles were conducted at two agricultural sites (cropland and livestock) in ammonia-rich environments to understand the effect of ammonia on nitric acid-nitrate partitioning using a thermodynamic model and to suggest a possible strategy to control total nitrate (i.e.

Recyclable Magnetic MOF-Catalyzed Synthesis of 1-Aminoisoquinolines and 6-Aminophenanthridines from 5-(2-Bromoaryl)tetrazoles and 1,3-Diketones under Microwave Irradiation.

In this study, 5-(2-bromoaryl)tetrazoles were reacted with 1,3-diketones in DMF in the presence of a catalytic amount of magnetic Cu-MOF-74 (FeO@SiO@Cu-MOF-74) and a base under microwave irradiation to yield the corresponding 1-aminoisoquinolines. The FeO@SiO@Cu-MOF-74 catalyst could be easily recovered from the reaction mixture and reused four times without any significant loss of catalytic activity. An initial copper-catalyzed C(sp)-C(sp) bond formation accompanied by -Claisen deacylative cyclocondensation (for acyclic 1,3-diketones) and direct cyclocondensation (for cyclohexane-1,3-diones) is proposed as a key reaction pathway for this process.

Real-time monitoring of aqueous total N-nitrosamines by UV photolysis and chemiluminescence.

N-nitrosamines such as N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPIP), and N-nitrosopyrrolidine (NPYR) have been established as potent carcinogens that can induce diverse types of cancer. Several studies have extensively investigated the accurate quantification of total N-nitrosamines (TONO) and the intricate nature of the matrix in which they are detected. The potential for the formation of N-nitrosamines in post-combustion CO capture (PCCC) and water treatment has raised concerns.

Recyclable Magnetic Cu-MOF-74-Catalyzed C(sp)-N Coupling and Cyclization under Microwave Irradiation: Synthesis of Imidazo[1,2-]quinazolines and Their Analogues.

Magnetic Cu-MOF-74 (FeO@SiO@Cu-MOF-74) was synthesized for the first time by grafting MOF-74 (copper as the metal center) on the surface of core-shell magnetic carboxyl-functionalized silica gel (FeO@SiO-COOH), which was prepared by coating core FeO nanoparticles with hydrolyzed 2-(3-(triethoxysilyl)propyl)succinic anhydride and tetraethyl orthosilicate. The structure of FeO@SiO@Cu-MOF-74 nanoparticles was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared FeO@SiO@Cu-MOF-74 nanoparticles could be applied as a recyclable catalyst to the synthesis of N-fused hybrid scaffolds.

Synthesis of Imidazo[1,2-]phenanthridines by Recyclable Magnetic MOF-Catalyzed Coupling and Cyclization of 2-(2-Bromoaryl)imidazoles with Cyclohexane-1,3-diones Followed by Aromatization.

2-(2-Bromoaryl)imidazoles react with cyclohexane-1,3-diones in the presence of a catalytic amount of recyclable FeO@SiO@MOF-199 and a base to give the corresponding C-C coupled and cyclized products 6,7-dihydroimidazo[1,2-]phenanthridin-8(5)-ones in high yields. The magnetic MOF catalyst could be easily recovered and reused four times without any significant loss of catalytic activity. The coupled and cyclized scaffolds were aromatized to imidazo[1,2-]phenanthridines in high yields by a one-pot sequential procedure including reduction, dehydration, and oxidation.

Weak Base-Promoted Lactamization under Microwave Irradiation: Synthesis of Quinolin-2(1)-ones and Phenanthridin-6(5)-ones.

Quinolin-2(1)-ones and phenanthridin-6(5)-ones are synthesized in high yields by KCO-promoted cyclization of -aryl-β-bromo-α,β-unsaturated amides and -aryl-2-bromobenzamides in dimethylformamide under microwave irradiation.

Role of various factors affecting the photochemical treatment of -nitrosamines related to CO capture.

Post-combustion CO capture using amine solvents is the most feasible method of reducing anthropogenic CO emissions, which are the largest contributor to global warming. The formation of carcinogenic -nitrosamines (i.e.

Microwave-Assisted Cyclization under Mildly Basic Conditions: Synthesis of 6 H-Benzo[ c]chromen-6-ones and Their 7,8,9,10-Tetrahydro Analogues.

Aryl 2-bromobenzoates and aryl 2-bromocyclohex-1-enecarboxylates are cyclized by microwave irradiation in dimethylformamide in the presence of KCO to give the corresponding 6 H-benzo[ c]chromen-6-ones and their 7,8,9,10-tetrahydro analogues, respectively, in 50-72% yields. Aryl 3-bromoacrylates are also converted into 2 H-chromen-2-ones under the employed conditions.

Naphthalene emissions from moth repellents or toilet deodorant blocks determined using head-space and small-chamber tests.

The present study investigated the emissions of naphthalene and other compounds from several different moth repellents (MRs) and one toilet deodorant block (TDB) currently sold in Korea, using a headspace analysis. The emission factors and emission rates of naphthalene were studied using a small-scale environmental chamber. Paper-type products emitted a higher concentration of the total volatile organic compounds (VOCs) (normalized to the weight of test piece) than ball-type products, which in turn emitted higher concentration than a gel-type product.

Volatile pollutants emitted from selected liquid household products.

Background, Aim, And Scope: To identify household products that may be potential sources of indoor air pollution, the chemical composition emitted from the products should be surveyed. Although this kind of survey has been conducted by certain research groups in Western Europe and the USA, there is still limited information in scientific literature. Moreover, chemical components and their proportions of household products are suspected to be different with different manufacturers.

Pulmonary effects of inhaled limonene ozone reaction products in elderly rats.

d-Limonene is an unsaturated volatile organic chemical found in cleaning products, air fresheners and soaps. It is oxidized by ozone to secondary organic aerosols consisting of aldehydes, acids, oxidants and fine and ultra fine particles. The lung irritant effects of these limonene ozone reaction products (LOP) were investigated.

Characterization of emissions composition for selected household products available in Korea.

The present study investigated the emission composition for 59 household products currently sold in Korea, using a headspace analysis. The chemical composition and concentrations of total volatile organic compounds (VOCs) broadly varied along with products, even within the same product category. Up to 1-17 organic compounds were detected in the headspace gas phase of any one of the products.

Evidence for oligomer formation in clouds: reactions of isoprene oxidation products.

Electrospray ionization mass spectrometry (ESI-MS) was used to investigate product formation in laboratory experiments designed to study secondary organic aerosol (SOA) formation in clouds. It has been proposed that water soluble aldehydes derived from aromatics and alkenes, including isoprene, oxidize further in cloud droplets forming organic acids and, upon droplet evaporation, SOA. Pyruvic acid is an important aqueous-phase intermediate.

Isoprene forms secondary organic aerosol through cloud processing: model simulations.

Isoprene accounts for more than half of non-methane volatile organics globally. Despite extensive experimentation, homogeneous formation of secondary organic aerosol (SOA) from isoprene remains unproven. Herein, an incloud process is identified in which isoprene produces SOA.

Assessing truck driver exposure at the World Trade Center disaster site: personal and area monitoring for particulate matter and volatile organic compounds during October 2001 and April 2002.

The destruction of the World Trade Center (WTC) in New York City on September 11, 2001, created a 16-acre debris field composed of pulverized and burning material significantly impacting air quality. Site cleanup began almost immediately. Cleanup workers were potentially exposed to airborne contaminants, including particulate matter, volatile organic compounds, and asbestos, at elevated concentrations.

Origins of primary and secondary organic aerosol in Atlanta: results of time-resolved measurements during the Atlanta Supersite Experiment.

Time-resolved ambient particulate organic (OC) and elemental carbon (EC) data measured in Atlanta, GA, during the Atlanta Supersite Experiment (August3-September 1, 1999) were investigated to determine the temporal trends of atmospheric carbonaceous aerosol and to examine the relative contributions of primary and secondary OC to measured particulate OC. Mean 1-h average concentrations (ranges in parentheses) of PM2.5 OC, EC, and total carbon were 8.