Characterization of the monthly variation in (1 → 3)-ß-D-glucan concentrations in university laboratories.

We characterize the monthly variation in (1 → 3)-ß-D-glucan concentration measured over the course of 1 year, and we evaluate the characteristics of size selection using a two-stage cyclone sampler. The (1 → 3)-ß-D-glucan concentrations were measured in four bio-related laboratories. A total of 156 samples were collected using a new two-stage cyclone sampler. Analysis of (1 → 3)-ß-D-glucan was performed using the kinetic Limulus amebocyte lysate assay. The study showed that airborne (1 → 3)-ß-D-glucan concentrations were significantly higher in laboratory D (mean ± SD 1,105 ± 1,893 pg/m(3)) and in the spring (5,458 pg/m(3)). The highest concentration of (1 → 3)-ß-D-glucan occurred in the spring, particularly in May.

Mechanisms of norbornadiene dimerization to Binor-S using cationic Co(I), Rh(I), and Ir(I) catalysts.

We investigated the transition metal-catalyzed reaction mechanisms of NBD dimerization to Binor-S using cationic Co(I), Rh(I), and Ir(I) catalysts, using mPW1PW91, mPW1K, and B3LYP density functional methods. Our results indicate that the monomeric metal center has the ability to bind with four double bonds of two NBD molecules with a syn spatial geometry to form a penta-coordinated complex. We designed three possible pathways, but found two of them blocked. The favored pathway involves three steps from the reactant precursor to the product precursor: the first step is the formation of a single bond to connect two NBD units, the second is the alkene insertion leading to the formation of the three-membered ring structure, and the final step is the formation of the final product precursor. Orbital analysis showed metal...C-C sigma agostic interaction in the product precursor, which is in agreement with the previous experimental findings. In addition, we found that the solvent and counter-ions had significant effects on the dimerization reactions.

Effect of TiO2 particle size on the performance of viologen-anchored TiO2 electrochromic device.

The effect of TiO2 particle size on the performance of the electrochromic device (ECD) has been investigated in this work by applying the TiO2 nanoparticles in 7, 15, and 30 nm sizes. The phosphonated viologen, bis(2-phosphonoethyl)-4,4'-bipyridinium dibromide, was anchored on the TiO2 surfaces for the construction of ECD. The ECD derived from 7 nm-sized TiO2 demonstrated the highest contrast ratio with high optical transparency, whereas it showed the slowest switching response. The enhancement of coloration efficiency with decrease of TiO2 particle size is due to the increased amount of the anchored viologen on TiO2 electrode. On the other hand, the relatively slower switching response would be caused by the difficulty of diffusion for the electrolytes and counter-ions through the small pores of the nanocrystalline TiO2 electrode derived from 7 nm-sized nanoparticles.

Hydrogen fluoride (HF) substance flow analysis for safe and sustainable chemical industry.

In this study, the chemical substance flow of hydrogen fluoride (hydrofluoric acid, HF) in domestic chemical industries in 2014 was analyzed in order to provide a basic material and information for the establishment of organized management system to ensure safety during HF applications. A total of 44,751 tons of HF was made by four domestic companies (in 2014); import amount was 95,984 tons in 2014 while 21,579 tons of HF was imported in 2005. The export amount of HF was 2180 tons, of which 2074 ton (China, 1422 tons, U.S. 524 tons, and Malaysia, 128 tons) was exported for the manufacturing of semiconductors. Based on the export and import amounts, it can be inferred that HF was used for manufacturing semiconductors. The industries applications of 161,123 tons of HF were as follows: manufacturing of basic inorganic chemical substance (27,937 tons), manufacturing of other chemical products such as detergents (28,208 tons), manufacturing of flat display (24,896 tons), and manufacturing of glass container package (22,002 tons). In this study, an analysis of the chemical substance flow showed that HF was mainly used in the semiconductor industry as well as glass container manufacturing. Combined with other risk management tools and approaches in the chemical industry, the chemical substance flow analysis (CSFA) can be a useful tool and method for assessment and management. The current CSFA results provide useful information for policy making in the chemical industry and national systems. Graphical abstract Hydrogen fluoride chemical substance flows in 2014 in South Korea.

Toxicity and biodegradation of diamines.

Phytotoxicity and cytotoxicity of 2,4-diaminotoluene (2,4-D), 4,4'-methylenedianiline (4,4-D), and 1,6-hexanediamine (1,6-D) were investigated by observing the germination of young radish seeds and the viability of HeLa cells, respectively. 2,4-D showed the highest, 4,4-D intermediate, and 1,6-D lowest cytotoxicity. However, the phytotoxicity decreased in the order of 4,4-D > 2,4-D > 1,6-D. Contrary to the results previously reported, in the modified Sturm test the activated sludge degraded 2,4-D and 4,4-D as well as 1,6-D without any pre-acclimation. Ochrobacterium antropi was isolated for degradation of 2,4-D and 4,4-D and Pseudomonas citronellolis for 1,6-D degradation. Thielevia sp. was isolated as 2,4-D degrading fungus and Aspergillus sp. as 4,4-D and 1,6-D degrading fungus. The fungi degraded the diamines faster than the bacteria.