Growth fusion of submicron spherical boron carbide particles by repetitive pulsed laser irradiation in liquid media

We studied the fabrication of B₄C submicron particles by laser irradiation of boron nanoparticles dispersed in an organic solvent. The spherical shape of the formed particles suggests that instantaneous melt formation and solidification by quenching are involved in the particle-forming process. B₄C particles gradually became larger with irradiation time at relatively low laser fluence (1.5 J cm⁻² pulse⁻¹) by repetitive melting and fusion of the particles, and the B₄C yield increased with irradiation time to 90% for 600 min of irradiation. At higher laser fluences, the B₄C yield decreased due to the explosive ablation of boron or B₄C to form H₃BO₃, and thus only the larger B₄C particles were observed. The dielectric constant of the organic solvent also affected the generated B₄C particle size, probably due to the degree of particle aggregation. Thus, this technique can provide a new approach for fabricating spherical submicron particles of ceramic materials, such as carbides, with simple and safe processes.     

Optimization of the dopant for the trace determination of polycyclic aromatic hydrocarbons by liquid chromatography/dopant-assisted atmospheric-pressure photoionization/mass spectrometry

The composition of the dopant for the analysis of polycyclic aromatic hydrocarbons (PAHs) by liquid chromatography/dopant-assisted atmospheric-pressure photoionization/mass spectrometry under reversed-phase conditions was optimized to enhance the ionization efficiency for PAHs. The most suitable dopant was a toluene/anisole mixture (99.5:0.5, v/v) and it could improve limit of detections (LODs) to 0.79-168 ng mL(-1) (signal-to-noise (S/N)=3) for 16 common PAHs. The LODs are 3.8-40 times lower than those obtained with toluene alone and are comparable to those obtained using gas chromatography/mass spectrometry.     

A novel dual antagonist of thromboxane A2 and leukotriene D4 receptors: synthesis and structure-activity relationships of chloroquinolylvinyl derivatives

To discover an orally active thromboxane A(2) (TXA(2)) and leukotriene D(4) (LTD(4)) dual antagonist, we designed and synthesized chloroquinolylvinyl derivatives based on the structures of the TXA(2) antagonist daltroban and the LTD(4) antagonist montelukast. Among these derivatives, 4-{[(2-(4-chlorophenylsulfonylamino)-1-{3-[(E)-2-(7-chloro-2-quinolyl)vinyl]phenyl}ethyl)thio]methyl}benzoic acid (18d) showed potent inhibitory activity against U46619-induced aggregation of guinea pig platelets and LTD(4)-induced contraction in the guinea pig ileum, with IC(50) values of 340 nm and 0.40 nm, respectively. Oral administration of 18 d also inhibited both the LTD(4)-induced acceleration of plasma leakage to skin in guinea pig and the U46619-induced increase in airway resistance in guinea pig with ED(50) values of 0.47 mg/kg and 3.3 mg/kg, respectively.     

Measurement of a genotoxic hydrazine, agaritine, and its derivatives by HPLC with fluorescence derivatization in the agaricus mushroom and its products

Agaricus blazei MURRILL mushroom products are sold as so-called health foods in Japan. However, a part of Agaricus is known to contain hydrazines. A sensitive and specific method for analyzing a genotoxic hydrazine, agaritine, and its derivatives was developed to assess the safety of Agaricus products. beta-N-(gamma-L(+)-Glutamyl)-4-(hydroxymethyl)phenylhydrazine (agaritine, AGT), 4-hydrazinylbenzylalcohol (HMPH), 4-hydrazinylbenzoic acid (CPH), 4-methylphenylhydrazine (MPH) and phenylhydrazine (PH) were converted to their correspond-ing fluorescent derivatives with 3,4-dihydro-6,7 dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride (DMEQ-COCl) as the fluorescence derivatization reagent. The detection limits (S/N=3) for CPH, AGT, PH and MPH were 422, 45.3, 16.5 and 138 fmol, respectively, in a 20 mul injection volume. Recoveries, achieved by adding known AGT amounts to the Agaricus sample and Agaricus products, ranged from 92.8 to 102%. By using this method which does not require partial purification of the Agaricus sample, the amounts of AGT in several types of foods were found to be 112-1836 mug/g dry weight.     

Stereoselective conversion of anhydrovinblastine into vinblastine utilizing an anti-vinblastine monoclonal antibody as a chiral mould

Dimeric indole alkaloid, anhydrovinblastine, which can be obtained from catharanthine and vindoline in a high yield, was converted stereoselectively into vinblastine through alternating oxidation-reduction with oxygen and NaBH(3)CN in the presence of anti-vinblastine monoclonal antibody.     

On -adic Hermitian Eisenstein series

In this paper we generalize the notion of -adic modular form to the Hermitian modular case and prove a formula that shows a coincidence between certain -adic Hermitian Eisenstein series and the genus theta series associated with Hermitian matrix with determinant .

     

Strong solutions to the Keller‐Segel system with the weak Ln /2 initial data and its application to the blow‐up rate

We shall show an exact time interval for the existence of local strong solutions to the Keller‐Segel system with the initial data u₀ in L^{n /2}_w (?ⁿ), the weak L^{n /2}‐space on ?ⁿ. If ‖u₀‖ is sufficiently small, then our solution exists globally in time. Our motivation to construct solutions in L^{n /2}_w (?ⁿ) stems from obtaining a self‐similar solution which does not belong to any usual L^p(?ⁿ). Furthermore, the characterization of local existence of solutions gives us an explicit blow‐up rate of ‖u (t)‖ for n /2 < p < ∞ as t → T_max, where T_max denotes the maximal existence time (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)