Measurements of the line strengths,N2− and O2-broadened half-widths in the ν3, ν1+2ν2 and 2ν1 bands of 14N2 16O at room temperature

The line strengths, N₂? and O₂-broadened half-widths in the ν₃, ν₁+2ν₂ and 2ν₁ bands of ¹⁴N₂ ¹⁶O were determined from spectra obtained by a high-resolution Fourier transform spectrometer at room temperature. The squared vibrational transition dipole moments and the coefficients of the Herman–Wallis factor were also determined for these bands. The squared vibrational transition dipole moments for these bands agreed with the values of HITRAN and high-resolution experiments within 6%. The N₂? and O₂-broadened half-widths were in agreement with the results of recent high-resolution experiments. The air-broadened half-widths were calculated using the smoothed N₂? and O₂-broadened half-widths and compared with the compiled values in the HITRAN database.     

Pretreatment of water samples using UV irradiation-peroxodisulfate for the determination of total mercury

Potassium peroxodisulfate (14 g l⁻¹, 25 ml) has been observed to readily oxidize water under UV irradiation (30 W mercury arc tube), even at room temperature. The reaction is complete in 20 min, producing oxygen in stoichiometric amounts. The reaction was applied to pretreatment for the determination of total mercury by cold vapor atomic absorption spectrometry (AAS).The response of mercury(II) chloride by the UV irradiation method was higher than that by the standard permanganate method (95 °C, 2 h). The conversion efficiency of mercury by the UV irradiation method, the standard method and by non-treatment was found to be 100, 93.6 and 85.0%, respectively. The study is also applied to methylmercury, ethylmercury and phenylmercury chlorides.     

The circular bacteriocins gassericin A and circularin A

Gassericin A, a bacteriocin produced by Lactobacillus gasseri LA39, shows antibacterial activity against a number of Gram-positive food-borne pathogenic bacteria. Circularin A produced by Clostridium beijerinckii ATCC25752 is active against C. tyrobutyricum, a known cheese-spoilage bacterium. Both bacteriocins were purified to homogeneity from culture supernatants by reverse-phase chromatography and the subsequently determined amino acid sequences were used to clone the bacteriocin structural genes. Mature gassericin A and circularin A are class V circular bacteriocins comprised of 58 and 69 amino acid residues, respectively. Both bacteriocins are resistant to several peptidases and proteases, as are other cyclic bacteriocins. Heterologous expression of gassericin A in Escherichia coli was used to produce a non-cyclic mature peptide, which was shown to have a specific activity 173-fold lower than the circular molecule. The minimal region for production and secretion of active circularin A is comprised of five genes, as was deduced by heterologous gene expression in Enterococcus faecalis. Gassericin A and circularin A have limited mutual similarity in their primary sequences. Unlike most bacteriocins, including gassericin A, circularin A has a three-amino-acid-leader sequence.     

Structure of monardaein,a bis-malonylated anthocyanin isolated from golden balm, monarda didyma

Structure of monardaein was determined to be 3-0-(6-0-$\text{trans}$-p-coumaryl-β-D-glucopyranosyl)-5-O- (4,6-di-O-malonyl-β-D-glucopyranosyl) pelargonidin (1).     

Syntheses of effectively-shielded N-heterocyclic carbene ligands

A novel type of N-heterocyclic carbene ligand, with a bicyclic motif at the non-carbenic carbons of an imidazolin-2-ylidene core, has been developed. This type of ligand formed an air and moisture stable silver complex even with N,N′-dimethyl NHC. Allylic arylation with a Grignard reagent catalyzed by copper complexes of the NHC ligands proceeded preferentially at the γ-position, indicating the effective steric shielding ability of this framework.     

Systematic control of size,shape, structure,and magnetic properties of uniform magnetite and maghemite particles

As an application of the gel-sol method especially developed for the synthesis of general monodisperse particles in large quantities, uniform hematite (alpha-Fe2O3), magnetite (Fe3O4), and maghemite (gamma-Fe2O3) particles, precisely controlled in size, aspect ratio, and internal structure, have been prepared. For the synthesis of uniform ellipsoidal single-crystal particles of alpha-Fe2O3, a highly condensed suspension of fine beta-FeOOH particles doped with a prescribed amount of PO4(3-) ion in their interiors was aged at 140 degrees C for 24 h with seed particles of alpha-Fe2O3 in an acidic medium containing optimum concentrations of HCl and NaNO3. Systematic control of the aspect ratio and mean size was achieved by regulating the concentration of PO4(3-) ion incorporated into the beta-FeOOH particles and the number of seeds added. The resulting hematite particles were converted into magnetite by reduction in a H2 stream at 330 degrees C for 6 h; the magnetite was then oxidized to maghemite in an air stream at 240 degrees C for 2 h. Magnetite and maghemite thus prepared retained the original shape of the hematite. On the other hand, polycrystalline hematite particles of different sizes and aspect ratios were also prepared by aging a condensed Fe(OH)3 gel in the presence of different concentrations of SO4(2-) ion and seeds. The polycrystalline hematite particles were similarly converted into magnetite and then maghemite. The magnetic properties of these magnetite and maghemite particles were analyzed as a function of their mean particle volume, aspect ratio, and internal structure.     

Determination of absolute configuration of a metabolite (−)-hydroxyhexamide from acetohexamide, syntheses of (−)- and (+)-hydroxyhexamides and (−)- and (+)-acetoxyhexamides

Enantioselective acetylation of (±)-4-(1-hydroxyethyl)benzenesulfonamide 6 with ‘Acylase I’ (No. A 2156) from Aspergillus melleus in the presence of vinyl acetate gave (R)-4-(1-acetoxyethyl)benzenesulfonamide 7 (98% ee) and (S)-6 (98% ee). Both (S)-6 and (R)-7 were individually converted to the (S)-hydroxyhexamide 2 (>99% ee) and (R)-hydroxyhexamide 2 (>99% ee), respectively. The absolute configuration of a metabolite (−)-hydroxyhexamide 2 from acetohexamide 1 was found to be S based on unequivocal chemical methods including X-ray analysis.     

Direct coating of quantum dots with silica shell

This paper describes a method for direct coating of fluorescent semiconductor nanoparticles with silica shell. The fluorescent semiconductor nanoparticles used were CdSe _x Te_1–x nanoparticles coated with ZnS and succeedingly surface-modified with carboxyl groups, or quantum dots (Q-dots). The Q-dots were silica-coated by performing sol–gel reaction of tetraethyl orthosilicate (TEOS) using NaOH as a catalyst in the presence of the Q-dots. Quasi-perfect Q-dots/silica core-shell particles were formed at 5.0 M H₂O and 4.0 × 10⁻⁴ M NaOH. Under these concentrations of H₂O and NaOH, the particle size of Q-dots/silica particles could be varied from 20.1 to 38.1 nm as the TEOS concentration increased from 2.5 × 10⁻⁴ to 50 × 10⁻⁴ M. The Q-dots/silica particles showed fluorescence as well as the uncoated Q-dots.     

MALDI-Q-TOF mass spectrometric determination of gold and platinum in tissues using their diethyldithiocarbamate chelate complexes

A rapid determination method is presented for gold (Au³⁺) and platinum (Pt⁴⁺) in tissues using matrix-assisted laser desorption ionization quadrupole time-of-flight mass spectrometry (MALDI-Q-TOF-MS). Au and Pt ions in wet-ashed tissue solution were reacted with diethyldithiocarbamate (DDC), and the resulting chelate complex ions Au(DDC)₂ ⁺ and Pt(DDC)₃ ⁺ were detected by MALDI-Q-TOF-MS using α-cyano-4-hydroxycinnamic acid as a matrix. The limit of detection (LOD) was 0.8 ng/g tissue and the quantification range was 2–400 ng/g for Au, and the LOD was 6 ng/g tissue and the quantification range was 20–4,000 ng/g for Pt. The Pt levels detected by MALDI-Q-TOF-MS in several tissues of a patient overdosed with cisplatin were nearly the same as those detected by flow-injection electrospray ionization mass spectrometry. The LODs of Au and Pt were 0.04 pg per well (sample spot) and 0.3 pg per well, respectively. To our knowledge, this is the first attempt to quantify Au³⁺ and Pt⁴⁺ ions in tissues by MALDI-Q-TOF-MS.

Diketopyrrolopyrrole J‐Aggregates Formed by Self‐Organization with DNA

Bis(2‐thienyl)diketopyrrolopyrrole with two Zn^II‐cyclens (ZnCyc‐DPP) was designed and synthesized to evaluate the selective binding of Zn^II‐cyclen with thymine base in single‐strand DNA as a tool for the construction of a highly ordered multichromophore system on DNAs. Through UV/Vis titrations, gel filtration chromatography, and circular dichroism spectroscopy, ZnCyc‐DPP formed J‐type DPP aggregates with oligo‐dT_n DNAs. The DPP aggregates absorbed on a gold electrode exhibited good photocurrent responses. The present results show that binding Zn^II‐cyclen–chromophore conjugates and thymine bases together is a powerful tool for preparing DNA‐templated multichromophoric systems with specific functions.