Measuring instrument of carbon dioxide concentration in seawater

The Measuring instrument of carbon dioxide concentration in seawater (pCO(2)) is developed. The instrument consists of an equilibrator, a non-dispersive infrared gas analyzer (NDIR), a carrier gas generator and a processing signal generator. The equilibrator has a cross section of 3 c㎡ and is 15 cm tall. The principle of pCO(2) measurement is based on the equilibration of a carrier gas phase with a seawater sample and subsequent determination of the carbon dioxide concentration in the carrier gas. The carrier gas circuit of the NDIR is opened to the atmosphere to maintain the carrier gas line at a barometric pressure. The present instrument can measure pCO(2) within the measuring error of about 2 ppm with sample water of about 180ml every 20 min

Cellular adverse actions of dibromoacetonitrile, a by-product in water bacterial control, at sublethal levels in rat thymocytes

The aim of this study was to investigate the effects of dibromoacetonitrile (DBAN), a by-product in water bacterial control, at sublethal concentrations on rat thymocytes, by using a cytometric technique with appropriate fluorescent dyes. By using this method, the possibility that DBAN induces cellular actions related to oxidative stress was assessed. DBAN reduced the content of cellular nonprotein thiols under Zn2+-free conditions. It elevated the intracellular level of Zn2+, being independent from external Zn2+. DBAN increased cell vulnerability to the cytotoxic action of hydrogen peroxide. These actions of DBAN were likely related to oxidative stress. DBAN is formed by the reaction of bromides and chlorinated oxidants during water disinfection. Hydrolysis of 2,2-dibromo-3-nitrilopropionamide, an antimicrobial used in hydraulic fracturing fluids for production of shale gas and oil, produces DBAN. Therefore, the concern regarding the levels of DBAN in industrial water systems is necessary to avoid the environmental risk to humans and wild mammals

Conflicting actions of 4-vinylcatechol in rat lymphocytes under oxidative stress induced by hydrogen peroxide

4-Vinylcatechol (4VC) has been identified as an aroma compound in roasted foods, especially coffee. It is also a component in traditional herbal medicines. This compound may be subconsciously ingested through foods and herbs. Recent experimental evidence has shown that 4VC possesses an antioxidative action. However, the antioxidative action of 4VC at cellular levels is not well characterized. The effects of 4VC (0.1–100 μM) were examined on rat thymic lymphocytes without and with oxidative stress induced by 300 μM hydrogen peroxide (H2O2). Cell treatment with 100 μM 4VC alone for 4 hr significantly increased the population of dead cells. Thus, 4VC at 100 μM or above elicits cytotoxicity. However, 4VC at sublethal concentrations (1–10 μM) significantly attenuated the H2O2-induced increase in cell lethality in a concentration-dependent manner. While application of 10 μM 4VC slowed the process of cell death induced by H2O2, 4VC did not antagonize the H2O2-induced reduction of cellular nonprotein thiols. Although 4VC at 10 μM did not affect intracellular Ca2+ and Zn2+ levels, the agent potentiated the H2O2-induced increases in these levels. These actions of 10 μM 4VC are adverse to the cells under the oxidative stress. However, 10 μM 4VC partly attenuated the cell death induced by 100 nM A23187, a calcium ionophore. There are conflicting actions of 4VC at 1–100 μM on the cells under oxidative stress although the agent is used for an antioxidant. Thus, caution is required when using 4VC as a therapeutic agent

Regular-Triangle Trimer and Charge Order Preserving the Anderson Condition in the Pyrochlore Structure of CsW2_2O6_6

Since the discovery of the Verwey transition in magnetite, transition metal compounds with pyrochlore structures have been intensively studied as a platform for realizing remarkable electronic phase transitions. We report the discovery of a unique phase transition that preserves the cubic symmetry of the beta-pyrochlore oxide CsW$_2$O$_6$, where each of W 5d electrons are confined in regular-triangle W3 trimers. This trimer formation is an unprecedented self-organization of d electrons, which can be resolved into a charge order satisfying the Anderson condition in a nontrivial way, orbital order caused by the distortion of WO6 octahedra, and the formation of a spin-singlet pair in a regular-triangle trimer. Electronic instability due to the unusual three-dimensional nesting of Fermi surfaces and the localized nature of the 5d electrons characteristic of the pyrochlore oxides were found to play important roles in this unique charge-orbital-spin coupled phenomenon.Comment: 7 pages, 3 figure