Synthesis, chemical properties and mutagenicity of 1,6- and 3,6-dinitrobenzo[a]pyrenes

Nitration of benzo[a]pyrene (BaP) with HNO3 (d = 1.38) produced a mixture of dinitroBaPs (1,6- and 3,6-isomers) and mononitroBaPs (1-, 3- and 6-isomers). Pure 1,6-dinitroBaP and 3,6-dinitroBaP were obtained by the reduction of the dinitroBaPs mixture with NaSH to yield the separable products 1-amino-6-nitroBaP and 3-amino-6-nitroBaP, followed by conversion to dinitroBaPs via the the diazonium salts. The half-wave potentials (E1/2) corresponding to the one-electron reduction of dinitroBaPs were measured and the relationship of these values to the mutagenicity is discussed.     

Liquid scintillation radioassay for multiple radionuclide mixtures by the most probable value theory

Multiple radionuclide mixtures which have similar scintillation pulse height distributions can be accurately radioassayed by the most probable value theory. This liquid scintillation technique is based on the construction of more observation equations than the number of nuclides to be analyzed. The technique has been applied to³H–¹⁴C–¹²⁵I and³H–¹⁴C–⁵¹Cr mixture samples, and found to be very practicable with the aid of computerized data processing for mixture samples having a wide range (ca. 10 times) of activity ratios.     

Properties of androsterone-sulfating sulfotransferase in female rat liver

Some properties of androsterone (AD)-sulfating sulfotransferase (ST) present in female rat livers were characterized. Based on the substrate specificities of the enzyme preparation obtained by anion exchange chromatography and 3'-phosphoadenosine 5'-phosphate (PAP)-agarose affinity chromatography, AD-ST was supposed to be among isoenzymes of hydroxysteroid STs. The identity of the AD-ST with the isoenzymes of hydroxysteroid ST, however, remains unclear at present. The enzyme preparation revealed a wide range of native molecular weight with a major Mr of some 600000. The AD-ST did not appear to have a homogeneous isoelectric point, because the enzymatic activity was spread over a wide range of the pH gradient, centering around pH 6.6 on chromatofocusing. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the AD-ST showed a subunit with Mr of 30000, which was similar to the hydroxysteroid STs purified previously. Under denaturing conditions the subunit was demonstrated to be composed of three protein species containing distinct pI values (pI 6.1, 6.7 and 7.2). The AD-ST was thus supposed to be an oligomer with high molecular weight, in which the subunits of different pI values are assembled in various association numbers.     

Anomalous momentum dependence of the superconducting coherence peak and its relation to the pseudogap of La1.85Sr0.15CuO4

We performed high-resolution angle-resolved photoemission spectroscopy on La1.85Sr0.15CuO4 to study the nature of the single-particle excitation gap. We found that there is a well-defined superconducting coherence peak in the off-nodal region while it is strongly suppressed around the antinode. The momentum dependence of the single-particle excitation gap shows a striking deviation from the dx-y2--wave symmetry with anomalous enhancement around the antinode in both the superconducting and the pseudogap state. The observed close correlation between the superconducting coherence peak and the pseudogap suggests a substantial contribution of the pseudogap to the anomalous behavior of the gap in the superconducting state.     

Parallel distributed block coordinate descent methods based on pairwise comparison oracle

The aim of this paper is to find the global solutions of uncertain optimization problems having a quadratic objective function and quadratic inequality constraints. The bounded epistemic uncertainties in the constraint coefficients are represented using either universal or existential quantified parameters and interval parameter domains. This approach allows to model non-controlled uncertainties by using universally quantified parameters and controlled uncertainties by using existentially quantified ones. While existentially quantified parameters could be equivalently considered as additional variables, keeping them as parameters allows maintaining the quadratic problem structure, which is essential for the proposed algorithm. The branch and bound algorithm presented in the paper handles both universally and existentially quantified parameters in a homogeneous way, without branching on their domains, and uses some dedicated numerical constraint programming techniques for finding a robust, global solution. Several examples clarify the theoretical parts and the tests demonstrate the usefulness of the proposed method.     

Rotating Navier-Stokes Equations in $${\mathbb R}^{3}_{+}$$ with Initial Data Nondecreasing at Infinity: The Ekman Boundary Layer Problem

We prove time local existence and uniqueness of solutions to a boundary layer problem in a rotating frame around the stationary solution called the Ekman spiral. We choose initial data in the vector-valued homogeneous Besov space for 2 <  p <  ∞. Here the L ^p -integrability is imposed in the normal direction, while we may have no decay in tangential components, since the Besov space contains nondecaying functions such as almost periodic functions. A crucial ingredient is theory for vector-valued homogeneous Besov spaces. For instance we provide and apply an operator-valued bounded H ^∞-calculus for the Laplacian in for a general Banach space .     

Proton transport properties of poly(aspartic acid) with different average molecular weights

We synthesized seven partially protonated poly(aspartic acids)/sodium polyaspartates (P-Asp) with different average molecular weights to study their proton transport properties. The number-average degree of polymerization (DP) for each P-Asp was 30 (P-Asp30), 115 (P-Asp115), 140 (P-Asp140), 160 (P-Asp160), 185 (P-Asp185), 205 (P-Asp205), and 250 (P-Asp250). The proton conductivity depended on the number-average DP. The maximum and minimum proton conductivities under a relative humidity of 70% and 298 K were 1.7 · 10^?3 S cm^?1 (P-Asp140) and 4.6 · 10^?4 S cm^?1 (P-Asp250), respectively. Differential thermogravimetric analysis (TG-DTA) was carried out for each P-Asp. The results were classified into two categories. One exhibited two endothermic peaks between t = (270 and 300) °C, the other exhibited only one peak. The P-Asp group with two endothermic peaks exhibited high proton conductivity. The high proton conductivity is related to the stability of the polymer. The number-average molecular weight also contributed to the stability of the polymer.     

Stereoselective vinylogous Mukaiyama aldol reaction of α-haloenals

We have developed a high-yielding and stereoselective vinylogous Mukaiyama aldol reaction (VMAR) of α-haloenals. Contrary to the simple α,β-unsaturated aldehyde, α-haloenals were found to be reactive affording the corresponding VMAR adducts in excellent yields. Some transformations of VMAR adducts by Pd-mediated cross-coupling were also examined in order to demonstrate the synthetic utility of VMAR of α-haloenals.     

A probable hydrogen-bonded Meisenheimer complex: an unusually high S(N)Ar reactivity of nitroaniline derivatives with hydroxide ion in aqueous media

Observations show that nitroanilines exhibit an unusually high S(N)Ar reactivity with OH(-) in aqueous media in reactions that produce nitrophenols. S(N)Ar reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH(2) group far surpasses that of Cl under these conditions. An essential feature of S(N)Ar reactions of nitroanilines is probably that the NH(2) leaving group participates in a hydrogen-bonding interaction with H(2)O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH(-), and H(2)O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S(N)Ar reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.