Radiological characterization of commercially available “radon spa sources”

Nowadays, artificial “radon spa sources” for home baths are commercially available. Although these sources could give a potential radiation exposure to the users, few studies have been reported on their radiological measurements. In the present study, five types of radon spa sources were collected and their radiological characterization was investigated. The followings were estimated for these samples: (1) radon emanation coefficients (dry and water-saturated conditions), (2) surface γ-ray dose rate, (3) surface count rates for α- and β-rays, (4) activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K, and (5) concentrations of radon and thoron generated from the sources located in an air flow system. The activity concentrations were very high (except for one sample (named “sample B”), although radon emanation coefficient was low compared with soil. This leads to high concentrations of radon/thoron generated from the sample. The maximum surface γ-ray dose rate was observed for sample A (2.7 μGy h⁻¹). If people stay very close to the sample for a long time, the exposure might be significant.     

Effective chemoselective deprotection of 3,4-dimethoxybenzyl (DMB) ethers in the presence of benzyl and p-methoxybenzyl (PMB) ethers by phenyliodine(III) bis(trifluoroacetate) (PIFA)

In this Letter, a selective deprotection of the alcohol protecting 3,4-dimethoxybenzyl (^3,4DMB) group is described. The hypervalent iodine(III) reagent phenyliodine bis(trifluoroacetate) (PIFA) is found to be an efficient reagent for the chemoselective deprotection of ^3,4DMB ethers in the presence of benzyl, p-methoxybenzyl, methoxymethyl, tert-butyldimethylsilyl, and tert-butyldiphenylsilyl ethers under mild conditions. This is the first example of the selective deprotection of the ^3,4DMB group from a hydroxy group with PIFA.     

A novel hybrid mode of sample injection to enhance CZE sensitivity for simultaneous determination of a pyridine-triphenylborane anti-fouling agent and its degradation products

We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electrokinetic injection and vacuum injection to enhance detection sensitivity in CZE. Samples were introduced using both vacuum and electrokinetic injections simultaneously, with a water plug injected into the capillary prior to sample introduction (i.e. similarly to field-amplified sample injection, FASI). Using a sample mixture containing an anti-fouling agent applied to ship hulls, pyridine-triphenylborane and its degradation products (diphenylborinic acid, phenylboronic acid, and phenol) dissolved in ACN, the length of water plug, time, and voltage for sample introduction were optimized. The signal intensity (peak height) was found to be up to a 30-fold increased using HSIM by applying 4 kV for 4 s at the inlet end of the capillary as the cathode with supplementary vacuum in comparison with only vacuum injection for 4 s. The LODs (at a S/N of 3) for pyridine-triphenylborane, diphenylborinic acid, phenylboronic acid, and phenol were 0.88, 1.0, 21, and 23 μg/L, respectively. At the level of 0.04 mg/L, the RSDs (n=4, intra-day) for the above analytes were in the ranges of 1.9-11, 4.3-9.2, and 0.34-0.66% for peak area, peak height, and migration time, respectively. The HSIM is a simple and promising procedure useful for enhancing the sensitivity for both low-and high-mobility ions in CZE.     

“Triple Observation Method (TOM)” to Discriminate Optically Autofluorescence from Porphyrins Versus that from Copper-Metallothioneins

We propose a conclusive difference observed between the excitation conditions required to observe porphyrins and copper-metallothioneins in cells and/or tissues using an ordinary fluorescence microscope. We have emphasized the importance of examining the spectral properties of the emissions to avoid any serious mistakes such as confusing porphyrins with copper-metallothioneins in the liver and kidneys. However, microspectrophotometry is not a conventional method for either histochemical, cytochemical, or pathological studies because microspectrophotometers are both expensive and difficult to operate. Therefore, we demonstrate a simple comparative method using ordinary excitation filter arrangements. When using our technique, it becomes possible to optically discriminate more accurately between the autofluorescence properties arising from porphyrins and those arising from copper-metallothioneins. We would like to name our simple technique “Triple Observation Method (TOM)”.     

Very simple,carbuncle-free,boundary-layer-resolving,rotated-hybrid Riemann solvers

In this paper, we propose new Euler flux functions for use in a finite-volume Euler/Navier–Stokes code, which are very simple, carbuncle-free, yet have an excellent boundary-layer-resolving capability, by combining two different Riemann solvers into one based on a rotated Riemann solver approach. We show that very economical Euler flux functions can be devised by combining the Roe solver (a full-wave solver) and the Rusanov/HLL solver (a fewer-wave solver), based on a rotated Riemann solver approach: a fewer-wave solver automatically applied in the direction normal to shocks to suppress carbuncles and a full-wave solver applied, again automatically, across shear layers to avoid an excessive amount of dissipation. The resulting flux functions can be implemented in a very simple and economical manner, in the form of the Roe solver with modified wave speeds, so that converting an existing Roe flux code into the new fluxes is an extremely simple task. They require only 7–14% extra CPU time and no problem-dependent tuning parameters. These new rotated fluxes are not only robust for shock-capturing, but also accurate for resolving shear layers. This is demonstrated by an extensive series of numerical experiments with standard finite-volume Euler and Navier–Stokes codes, including various shock instability problems and also an unstructured grid case.     

Time-resolved infrared diode laser spectroscopy of the ν1 (C-O stretch) band of the CoCO radical

Infrared spectrum of the cobalt carbonyl radical CoCO produced by the 193 nm excimer laser photolysis of cobalt tricarbonyl nitrosyl Co(CO)₃NO was observed by time-resolved diode laser spectroscopy. More than 600 lines were identified as belonging to the ν₁ (C-O stretch) fundamental band, consisting of the Ω=5/2 and 3/2 subbands, and the associated hot bands , , , and . The ²Δ_i electronic ground state of CoCO was experimentally confirmed. The ν₁ band origins are 1974.172582(93) cm⁻¹ and 1973.53178(14) cm⁻¹ for the Ω=5/2 and 3/2 subbands, respectively. The rotational constant in the ground state was determined as B₀=4427.146(50) MHz. The centrifugal distortion constant D₀=1.1243(68) kHz was obtained for the Ω=5/2 substate of the ground state. The equilibrium rotational constant B_e=4435.44(14) MHz was derived, together with the vibration-rotation interaction constants.     

Remarkable emissions in diprotonated 2,2′:6′,2″‐terpyridine derivatives

A series of new metal‐free blue emission compounds, i.e., diprotonated terpyH₂ClPF₆ ( 1 ), tterpyH₂ClPF₆ ( 2 ), ClterpyH₂ClPF₆ ( 3 ), and BterpyH₂(PF₆)₂ ( 4 ), were prepared and characterized by electrospray ionization mass spectrometry, UV–vis spectroscopy, and cyclic voltammetry (CV). Abbreviations used are terpy = 2,2′:6′,2″‐terpyridine, tterpy = 4′‐(4‐tolyl)‐2,2′:6′,2″‐terpyridine, Clterpy = 4′‐chloro‐2,2′:6′,2″‐terpyridine, and Bterpy = 4,4′,4″‐tert‐butyl‐2,2′:6′,2″‐terpyridine. The X‐ray crystal structures of the three new compounds 1, 2, and 4 were determined. Both protonated pyridine rings of the terpyridine derivatives are hydrogen bonded intermolecularly to the adjacent Cl^? ion in compounds 1 , 2, and 3 . The π–π* absorption bands in the UV region for 1, 2, 3, and 4 in acetonitrile were red‐shifted relative to those of the corresponding neutral compounds. All the compounds exhibited stronger emissions (around 400 nm) than their neutral counterparts. All the CVs for the diprotonated species, terpyH, tterpyH, ClterpyH, and BterpyH, showed the first reduction waves around ?0.6 V, which were more positive than those of the neutral ones. Density functional theory was applied to interpret the remarkable differences in the interaction of the Cl^? ion. The attachment of two protons to the two terminal Bterpy nitrogens in 4 elicits remarkable characteristics. Both positive charges on the nitrogens are delocalized over the conjugated pyridine systems and the tertiary carbonium ions are stabilized to lead to stronger emission (Φ = 0.35) than the corresponding neutral Bterpy (Φ = 0.045). CCDC 732045–732047 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal neutron cross section and resonance integral of the reaction of135Cs(n,γ)136Cs: Fundamental data for the transmutation of nuclear waste

To determine the cross sections of the¹³⁵Cs(n,γ)¹³⁶Cs reaction, a sample of¹³⁵Cs included in a “standardized solution” of¹³⁷Cs was used as a target and irradiated in a reactor. The ratio of the atom number of¹³⁵Cs to that of¹³⁷Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.     

Ab initio calculations for the N(2D) + CH4 reaction: Does the N(2D) atom really insert into CH bonds of alkane molecules?

The geometry of the transition state for the N(²D) + CH₄ reaction has been reoptimized at the complete‐active‐space self‐consistent field theory with a large active space and we have confirmed that the N(²D) atom initially inserts into a CH bond to form adiabatically an intermediate radical, CH₃NH(²A″). Extensive single‐point calculations at the multireference configuration interaction level of theory have also been carried out to understand the feature of the potential energy surface for the C–H insertion reaction. In addition, we have found that the N(²D)+CH₄ reaction dynamics on the second lowest doublet state (²A′) is dominated by C–H insertion although the barrier height is somewhat larger in energy than the corresponding insertion barrier associated with the lowest doublet state. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 190–197, 2000