LC-MS/MS and chiroptical spectroscopic analyses of multidimensional metabolic systems of chiral thalidomide and its derivatives.

Enantiomeric thalidomide undergoes various kinds of biotransformations including chiral inversion, hydrolysis, and enzymatic oxidation, which results in several metabolites, thereby adding to the complexity in the understanding of the nature of thalidomide. To decipher this complexity, we analyzed the multidimensional metabolic reaction networks of thalidomide and related molecules in vitro. Characteristic patterns in the amount of various metabolites of thalidomide and related molecules generated during a combination of chiral inversion, hydrolysis, and hydroxylation were observed using liquid chromatography-tandem mass spectrometry and chiroptical spectroscopy.

Tip characterization method using multi-feature characterizer for CD-AFM.

In atomic force microscopy (AFM) metrology, the tip is a key source of uncertainty. Images taken with an AFM show a change in feature width and shape that depends on tip geometry. This geometric dilation is more pronounced when measuring features with high aspect ratios, and makes it difficult to obtain absolute dimensions.

Spectral modulation of higher harmonic spontaneous emission from an optical klystron.

Higher harmonics of spontaneous emission from an optical klystron have been observed. The modulation factor of the spontaneous emission spectrum for the higher harmonics can be described by considering the observation system. When the dispersive gap of the optical klystron was fixed, the microstructure interval of the spontaneous emission spectrum at a certain resonant wavelength became narrower as the order of the higher harmonic became larger.

Positron annihilation in cardo-based polymer membranes.

Positron annihilation lifetime spectroscopy (PALS) is applied to a series of bis(aniline)fluorene and bis(xylidine)fluorene-based cardo polyimide and bis(phenol)fluorene-based polysulfone membranes. It was found that favorable amounts of positronium (Ps, the positron-electron bound state) form in cardo polyimides with the 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) moiety and bis(phenol)fluorene-based cardo polysulfone, but no Ps forms in most of the polyimides with pyromellitic dianhydride (PMDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BTDA) moieties. A bis(xylidine)fluorene-based polyimide membrane containing PMDA and BTDA moieties exhibits a little Ps formation but the ortho-positronium (o-Ps, the triplet state of Ps) lifetime of this membrane anomalously shortens with increasing temperature, which we attribute to chemical reaction of o-Ps.

Formation of three-way scanning electron microscope moiré on micro/nanostructures.

Three-way scanning electron microscope (SEM) moiré was first generated using a designed three-way electron beam (EB) in an SEM. The spot-type three-way SEM moiré comes from the interference between the three-way EB and the specimen grating in which the periodic cells are arranged in a triangular manner. The deformation and the structure information of the specimen grating in three directions can be simultaneously obtained from the three-way SEM moiré.

Thermal behavior of poly(lactic acid)-nanocomposite studied by near-infrared imaging based on roundtrip temperature scan.

The thermal behavior of poly(lactic acid) (PLA) was studied by near-infrared imaging to provide a molecular-level understanding of the physical improvement caused by nanoclay dispersion. A set of PLA samples, each having different nanoclay dispersion, was prepared under varying sonication time. Crystallinity variation of the polymer interacting with the nanoclay particles was analyzed by a roundtrip temperature scan below the melting temperature.

Power of isotopic fine structure for unambiguous determination of metabolite elemental compositions: in silico evaluation and metabolomic application.

In mass spectrometry (MS)-based metabolomics studies, reference-free identification of metabolites is still a challenging issue. Previously, we demonstrated that the elemental composition (EC) of metabolites could be unambiguously determined using isotopic fine structure, observed by ultrahigh resolution MS, which provided the relative isotopic abundance (RIA) of (13)C, (15)N, (18)O, and (34)S. Herein, we evaluated the efficacy of the RIA for determining ECs based on the MS peaks of 20,258 known metabolites.

Photon-induced positron annihilation lifetime spectroscopy using ultrashort laser-Compton-scattered gamma-ray pulses.

High-energy ultrashort gamma-ray pulses can be generated via laser Compton scattering with 90° collisions at the UVSOR-II electron storage ring. As an applied study of ultrashort gamma-ray pulses, a new photon-induced positron annihilation lifetime spectroscopy approach has been developed. Ultrashort gamma-ray pulses with a maximum energy of 6.

Multiple-perturbation two-dimensional near-infrared correlation study of time-dependent water absorption behavior of cellulose affected by pressure.

Transient water absorption by cellulosic samples manufactured under varying pressure was monitored by near-infrared spectroscopy to explore the absorption behavior affected by the pressure. A substantial level of variation of the spectral features was induced by the water absorption and changes in the pressure. The detail of the spectral changes was analyzed with a multiple-perturbation, two-dimensional (2D) correlation method to determine the underlying mechanism.

X-ray absorption near edge spectroscopy with a superconducting detector for nitrogen dopants in SiC.

Fluorescence-yield X-ray absorption fine structure (FY-XAFS) is extensively used for investigating atomic-scale local structures around specific elements in functional materials. However, conventional FY-XAFS instruments frequently cannot cover trace light elements, for example dopants in wide gap semiconductors, because of insufficient energy resolution of semiconductor X-ray detectors. Here we introduce a superconducting XAFS (SC-XAFS) apparatus to measure X-ray absorption near-edge structure (XANES) of n-type dopant N atoms (4 ×10(19) cm(-3)) implanted at 500°C into 4H-SiC substrates annealed subsequently.

Diffraction-enhanced X-ray imaging under low-temperature conditions: non-destructive observations of clathrate gas hydrates.

Diffraction-enhanced imaging (DEI) is a phase-contrast X-ray imaging technique suitable for visualizing light-element materials. The method also enables observations of sample-containing regions with large density gradients. In this study a cryogenic imaging technique was developed for DEI-enabled measurements at low temperature from 193 K up to room temperature with a deviation of 1 K.

Accelerated weathering-induced degradation of poly(lactic acid) fiber studied by near-infrared (NIR) hyperspectral imaging.

Hydrolysis degradation of a set of drawn poly(lactic acid) (PLA) fibers was induced by an accelerated weathering test, radiating ultraviolet (UV) light under a certain temperature and humidity. The fine features of the transient behavior of the PLA fibers were captured by near-infrared (NIR) hyperspectral imaging. The PLA fibers showed a gradual decrease in mechanical property (e.

Parallel factor (PARAFAC) kernel analysis of temperature- and composition-dependent NMR spectra of poly(lactic acid) nanocomposites.

The parallel factor (PARAFAC) kernel matrix to analyze a sample system stimulated by more than one type of perturbation is described. PARAFAC kernel is a quantitative representation of the synchronicity and asynchronicity observed within the PARAFAC score matrices generated by carrying out two-dimensional (2D) correlation analyses. Thus, kernel matrix representation provides more intuitively understandable interpretation to the conventional PARAFAC trilinear model.

Innovative Trifluoromethyl Radical from Persistent Radical as Efficient Initiator for the Radical Copolymerization of Vinylidene Fluoride with -Butyl α-Trifluoromethacrylate.

A persistent perfluoroalkyl branched radical (PPFR), perfluoro-3-ethyl-2,4-dimethyl-3-pentyl, was shown to be a good source of CF radicals able to initiate the radical copolymerization of vinylidene fluoride (VDF) with -butyl α-trifluoromethacrylate (MAF-TBE). NMR characterizations of the resulting poly(VDF--MAF-TBE) copolymers showed that copolymerization was exclusively initiated by CF radicals, as evidenced by the thermal decomposition of PPFR above 80 °C. The addition of CF radical onto VDF/MAF-TBE system was regioselective leading to CF-CH-CF radical that further cross propagated onto MAF-TBE unit and the α,ω-trifluoromethyl group acted as an efficient label to assess the molecular weights of the resulting copolymers by F NMR spectroscopy.

Operation of higher harmonic oscillations in free-electron lasers.

We report for the first time the experimental achievement of a seventh-harmonic free-electron laser (FEL) oscillation. The measured FEL gains and average FEL powers for higher harmonics were identical to those calculated by a one-dimensional FEL theory. The measured linewidths of the higher-harmonic FELs were narrower than that of the fundamental FEL owing to the narrower spectral widths of the spontaneous emissions.

Lasing of middle-infrared free-election lasers using the storage ring NIJI-IV.

We report for the first time to our knowledge the experimental realization of a storage ring free-electron laser (FEL) in the middle-infrared (MIR) region. A technique to adjust the optical cavity using higher harmonic FELs was developed for a fundamental FEL in the MIR region. The MIR FELs were oscillated in the wavelength region of 2475 to 2673 nm, and the relative linewidth was 5×10⁻⁴.

Determination of oxygen content in magnesium and its alloys by inert gas fusion-infrared absorptiometry.

A method for the determination of the oxygen content in magnesium and magnesium alloys has been developed. Inert gas fusion-infrared absorptiometry was modified by introducing a multistep heating process; a sample containing oxygen is fused with tin to form an eutectic mixture at 900°C in a graphite crucible, followed by a subsequent gradual temperature increase of up to 2000°C, which enables the evaporation of magnesium from the mixture, and subsequent solidification at the rim of the crucible. Residual tin including magnesium oxide remained at the bottom of the crucible.

Phase-contrast X-ray imaging of the gas diffusion layer of fuel cells.

The understanding of and in situ observation of the transport and distribution of water in carbon-paper gas diffusion layers (GDLs) using non-destructive imaging techniques is critical for achieving high performance in polymer electrolyte fuel cells (PEFCs). To investigate the behavior of water in GDLs of PEFCs, phase-contrast X-ray imaging via X-ray interferometric imaging (XII) and diffraction-enhanced imaging (DEI) were performed using 35 keV X-rays. The XII technique is useful for the radiographic imaging of GDLs and in situ observations of water evolution processes in operating PEFCs.

Charge-state-derivation ion detection using a super-conducting nanostructure device for mass spectrometry.

Mass spectrometry (MS) is a method of analyzing ions based on their mass/charge (m/z) ratios. The m/z peak identification requires speculation on the ionic unit-charge states. This problem can be solved by using superconducting junction devices to measure the kinetic energies of single molecules.

Chiroptical study of α-aliphatic amino acid films in the vacuum ultraviolet region.

A series of natural circular dichroism (CD) and absorption spectra for films of α-aliphatic amino acids--such as alanine, aminobutyric acid, norvaline, norleucine, valine, leucine, and isoleucine--in the vacuum ultraviolet (VUV) region were observed with the absolute values of optical constants at the undulator-based CD beamline TERAS BL5. Preliminary predictions of some CD spectra were also performed, based on quantum-chemical calculations using the crystal structure. Although the absorption spectra show similar features to each other, significant differences between the CD spectra were found, especially in the 7-8 eV region.

Phase transition analysis of 5-aminotetrazole from room temperature to the melting point.

The phase transition behavior of the 5-aminotetrazole (5-ATZ) crystal was studied in the range of room temperature to the melting point by the differential scanning calorimetry and powder X-ray diffraction techniques to investigate the dehydration phenomenon and to obtain the physical state of the high temperature phase. We found that 5-ATZ has one monohydrate crystal phase and three anhydrous crystal phases (I, II, and III) up to its melting point. The dehydration reaction of the monohydrate crystal occurred at about 50 °C.

Fiber Bragg grating vibration-sensing system, insensitive to Bragg wavelength and employing fiber ring laser.

A fiber Bragg grating (FBG) vibration-sensing system employing a fiber ring laser utilizing an FBG sensor as the ring cavity mirror was designed and developed herein. The fiber ring laser emitted lasing light at the Bragg wavelength of the FBG sensor, and the intensity of the lasing light varied with vibrations applied to the FBG sensor. Experiments demonstrated that this system could detect, with good sensitivity, vibrations over a broad band, ranging from just a few hertz up to ultrasound.

Proton diffusion in the room-temperature phase of [(NH4)1-xRbx]3H(SO4)2 as studied by 1H spin-lattice relaxation in the rotating frame.

Proton diffusion in the room-temperature phase (phase II) of [(NH4)1-xRbx]3H(SO4)2 (0 View Article and Find Full Text PDF

Determination of residual dipolar interaction from transverse 1H NMR relaxation in elastomers.

The formula expressing the proton transverse magnetization decay for elastomers is reconsidered. It is improved by incorporating the relaxation contribution. The spin-spin relaxation times T2 are estimated from spin-lattice relaxation times in the laboratory frame T1 and spin-lattice relaxation times in the rotating frame T1rho measured at the low static magnetic field.