Efficient transformation of 7,14-dihydroxy-ent-kaurenes to novel ent-abietanes having cis-fused α-methylene γ-lactones under Mitsunobu reaction conditions and their cytotoxicities

Transformation of plant-origin 7,14-dihydroxy-ent-kaurenes to ent-abietanes having a cis-fused α-methylene γ-lactones was accomplished efficiently under the Mitsunobu reaction conditions. The yields of the desired products were apparently influenced by the steric hindrance at C-1. The cytotoxic activity on P388 murine leukemia cells of the ent-abietanes having cis-fused α-methylene γ-lactones produced were assayed.     

Recovery of palladium using chemically modified cedar wood powder

Japanese cedar wood powder (CWP) was chemically modified to a tertiary-amine-type adsorbent and studied for the selective recovery of Pd(II) from various industrial waters. Batch adsorption tests performed from 0.1 M to 5 M HCl and HNO₃ systems reveal stable performance with better results in HNO₃ medium. The maximum loading capacity for Pd(II) was studied in HCl as well as in HNO₃. A continuous-flow experiment taking a real industrial solution revealed the feasibility of using modified CWP for the selective uptake and preconcentration of traces of palladium contained in acidic effluents. In addition, stable adsorption performance even on long exposure to γ-irradiation and selective recovery of palladium from simulated high-level liquid waste (HLW) are important outcomes of the study.     

Synthesis of [carbonyl-C]acetophenone via the Stille cross-coupling reaction of [1-C]acetyl chloride with tributylphenylstannane mediated by Pd2(dba)3/P(MeNCH2CH2)3N·HCl

The Stille cross-coupling reaction of [1-¹¹C]acetyl chloride with tributylphenylstannane leading to [carbonyl-¹¹C]acetophenone was studied with the goal of developing a new ¹¹C-labeling method for positron emission tomography tracer synthesis. The coupled product [carbonyl-¹¹C]acetophenone was synthesized using the Pd₂(dba)₃/P(MeNCH₂CH₂)₃N·HCl system with a 60-61% radiochemical conversion from [1-¹¹C]acetyl chloride (decay-corrected, n = 3).     

A B3LYP study on counterpoise-corrected geometry optimizations for hydrated complexes of [K(H2O)n] and [Na(H2O)n]

We report the basis set dependencies and the basis set superposition errors for the hydrated complexes of K⁺ and Na⁺ ions in relation to the recent studies of the KcsA potassium channel. The basis set superposition errors are estimated by the geometry optimizations at the counterpoise-corrected B3LYP level. The counterpoise optimizations alter the hydration distances by about 0.02–0.03 Å. The enthalpies and free energies for K⁺ + n(H₂O) → [K(H₂O)_n]⁺ and Na⁺ + n(H₂O) → [Na(H₂O)_n]⁺ (n = 1–6) are compared between the theoretical and experimental values. The results show that the addition of diffuse functions to K, Na, and O species are effective. However, it is also found that the counterpoise corrections using diffuse functions work so as to underestimate the free energies for the complexes with increasing the hydration number. The stabilization energies in aqueous solution are larger for a Na⁺ ion than for a K⁺ ion, suggesting the contributions of their dehydration processes to the ion selectivity of the KcsA potassium channel. The changes in coordination distance between the isolated [K(H₂O)₈]⁺ and the [K(H₂O)₈]⁺ in the KcsA potassium channel indicate the importance of hydrogen bondings between the first hydration shell and the outer hydration shells.     

Kinetics of the dehydrochlorination of poly(vinyl chloride) in the presence of NaOH and various diols as solvents

The dehydrochlorination of PVC in the presence of NaOH was investigated in different diols. Diethylene glycol (DEG), triethylene glycol (TEG), and propylene glycol (PG) were found to be effective in accelerating the dechlorination of PVC. The dehydrochlorination was promoted in the order TEG > DEG > PG, which was in agreement with the compatibility between PET and the diol. Compatibility resulted in an improved penetration of the PVC particle by the solvent, leading to the acceleration of the dehydrochlorination. The dehydrochlorination of PVC in NaOH/diol followed first-order kinetics, confirming the progress of the reaction under chemical reaction control. The apparent activation energies were 82 kJ mol⁻¹, 109 kJ mol⁻¹, and 151 kJ mol⁻¹ for TEG, DEG, and PG, respectively. The lower the activation energy became the faster the dehydrochlorination of PVC proceeded.     

Automated on-line in-tube solid-phase microextraction coupled with HPLC/MS/MS for the determination of butyrophenone derivatives in human plasma

This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide, haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm × 0.32 mm i.d., film thickness 0.25 μm). The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL). The limits of detection and quantification in plasma for each drug were 0.03–0.2 and 0.1–0.5 ng/mL, respectively. The intra- and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%.     

100-femtosecond MeV electron source for ultrafast electron diffraction

A near-relativistic 100-fs MeV electron beam is developed by using a photocathode rf gun for revealing the hidden ultrafast dynamics of intricate molecular and atomic processes in materials through experimentation of ultrafast time-resolved electron diffraction (UED). The transverse and longitudinal dynamics of femtosecond electron beam in the rf gun were studied theoretically by particle simulation. The growths of the emittance, bunch length and energy spread due to the rf and space charge effects were investigated by changing the laser parameters, field gradient and electron charge. The theoretical studies indicate that a 100-fs MeV electron beam with the transverse emittance of 0.1 mm mrad and the relative energy spread of 10⁻³–10⁻⁴ at bunch charge of 0.1–2 pC (10⁶–10⁷ electrons per pulse) is achievable for UED, in which the intensity is three orders of magnitude higher than that produced by the conventional dc or pulsed guns.     

Transient absorption measurement system using pulsed energetic ion

This article reports a highly sensitive transient absorbance measurement system using pulsed energetic ions. The ions were pulsed by a beam chopper, which was synchronized with the cyclotron, and accelerated to the desired energy around 18 MeV/u. H, He, C and Ne ions can be used for the transient absorption measurement. The optical system can measure an absorbance smaller than 1.0×10⁻⁴ in the wavelength range of 400–740 nm.     

High-Field and Multifrequency ESR Studies at KYOKUGEN in Osaka University

We have developed high-field and multifrequency (HFMF) electron spin resonance (ESR) apparatus for the magnetic fields up to 65 T at frequencies up to about 6 THz. In addition to this pulsed field ESR apparatus, we are making a multifrequency ESR apparatus with very high sensitivity in a static field. We report the results of ESR studies on BaCoV₂O₈ and NiGa₂S₄, followed by recent developments and future plans of our HFMF ESR apparatus.     

A study on the role of gelatin in methacrylic-acid-based gel dosimeters

In radiotherapy treatment, polymer gel dosimetry can be used for verifying three-dimensional (3D) dose distributions. Gelatin is generally used as a gelling agent in the dosimeters. In this paper, another role of gelatin in a methacrylic-acid-based gel dosimeter (MAGAT) is investigated. Temperature increases due to exothermic polymerization in the irradiated gel are measured directly. Dose–R₂ responses are also obtained using MRI. It is shown that no appreciable increases in either temperature or R₂ are observed in MAGAT dosimeters made without gelatin, and that significant temperature and R₂ increases are observed when very low gelatin concentrations are used. These results indicate that gelatin is an important enabler for radiation-induced free-radical polymerization in methacrylic-acid-based gels. When gelatin is replaced by amino acids, changes in temperature are observed, along with small changes in R₂. The resulting dosimeter solutions remain transparent because the polymer does not precipitate as it does in regular MAGAT dosimeters containing gelatin. When the amino acids are replaced by acids without amino groups, no temperature or R₂ changes are observed, indicating that no polymer forms. These results show that amino groups (and possibly other functional groups) on the gelatin catalyze the radiation-induced free-radical polymerization that occurs in MAGAT dosimeters.