Synthetic application of 3,3-dichloro-1,1,1-trifluoroacetone (DCTFA) and 3,3,3-trichloro-1,1,1-trifluoroacetone (TCTFA) for trifluorolactic acid derivatives

Synthetic application of 3,3-dichloro-1,1,1-trifluoroacetone (DCTFA) and 3,3,3-trichloro-1,1,1-trifluoroacetone (TCTFA) for industrially important trifluorolactic acid derivatives is described. Trifluorolactic acid was obtained by hydrolysis of DCTFA under basic conditions. On the other hand, α-substituted trifluorolactic acid derivatives, such as α-methyltrifluorolactic acid and Mosher’s acid, were obtained by addition reaction between TCTFA and carbon nucleophiles, followed by subsequent transformation of trichloromethyl group.     

Generation of 0.1 THz coherent synchrotron radiation with compact S-band linac at AIST

The 0.1 THz coherent synchrotron radiation (CSR) was successfully generated in the 90° bending magnet of the compact S-band linac with the achromatic arc section using the ultra-short electron bunch which has the energy of 40 MeV, the bunch charge of about 1nc and the bunch length less than 1 ps (rms). The electron bunch compression of 1 nC electron bunch was achieved less than 1 ps (rms) by controlling the Q-magnets in the achromatic arc section as the bunch length was measured by the rms bunch length monitor.     

Determination of azaspiracids in shellfish using liquid chromatography/tandem electrospray mass spectrometry.

Azaspiracid (AZA1), a recently discovered marine toxin, is responsible for the new human toxic syndrome, azaspiracid poisoning (AZP), which is caused by the consumption of contaminated shellfish. A new, sensitive liquid chromatography/mass spectrometry (LC/MS) method has been developed for the determination of AZA1 and its analogues, 8-methylazaspiracid (AZA2) and 22-demethylazaspiracid (AZA3). Separation of these toxins was achieved using reversed-phase LC and coupled, via an electrospray ionisation (ESI) source, to an ion-trap mass spectrometer. Spectra showed the protonated molecules, [M + H]+, and their major product ions, due to the sequential loss of two water molecules, [M + H - H2O]+, [M + H - 2H2O]+, in addition to fragment ions that are characteristic of these cyclic polyethers. A highly specific and sensitive LC/MS(3) analytical method was developed and, using shellfish extracts containing AZA1, the detection limit (S/N = 3) was 4 pg on-column, corresponding to 0.8 ng/mL. Using the protocol presented here, this is equivalent to 0.37 ng/g shellfish tissue and good linear calibrations were obtained for AZA1 in shellfish extracts (average r2 = 0.9988). Good reproducibility was achieved with % RSD values (N = 5) ranging from 1.5% (0.75 microg/mL) to 4.2% (0.05 microg/mL). An efficient procedure for the extraction of toxins from shellfish aided the development of a rapid protocol for the determination of the three predominant azaspiracids.     

C5–C10 Directly Bonded Tetrodotoxin Analogues: Possible Biosynthetic Precursors of Tetrodotoxin From Newts

The identification of novel tetrodotoxin (TTX, 1 ) analogues would significantly contribute to the elucidation of its biosynthetic pathway. In this study, the first C5–C10 directly bonded TTX analogues, 4,9‐anhydro‐10‐hemiketal‐5‐deoxyTTX ( 2 ) and 4,9‐anhydro‐8‐epi‐10‐hemiketal‐5,6,11‐trideoxyTTX ( 3 ), were found in the newt Cynops ensicauda popei by using a screening method involving HILIC‐LC–MS/MS focused on the fragment ions of TTX analogues, and their structures were elucidated by spectroscopic methods. Compound 2 was detected in a wide range of newt species, and the 2 and TTX contents of 22 newt specimens were correlated (r_s=0.88). Based on these results and its structural features, 2 was predicted to serve as a precursor of TTX that would be directly converted into 4,9‐anhydroTTX ( 4 ) by Baeyer–Villiger‐like oxidation or via 4,9‐anhydro‐5‐deoxyTTX formed by cleavage of the C5–C10 bond. The bicyclic carbon skeletons of 2 and 3 suggested a possible monoterpene origin for TTX.     

Feasibility of using a surface plasmon resonance-based biosensor to detect and quantify yessotoxin

Yessotoxin (YTX) is a disulfated polyether toxin produced by marine dinoflagellates. Although there is no clear evidence that YTX is toxic to humans, it is a major cause of false positives in DSP toxin detection by mouse bioassay. We developed a new detection and quantification method for yessotoxin using a BiaCore X Surface plasmon resonance (SPR)-based biosensor. The assay is based in the interaction of YTX with phosphodiesterase enzymes (PDE), one of its cellular targets. The injection of several YTX concentrations (3-12 microM) over immobilized PDE I, showed a dose dependent binding signal, which K(obs) (observed rate constant) allowed us to obtain a calibration curve with a linear fit. The detection of yessotoxin using SPR-based biosensor allows the quantification of the toxin with an automated and repetitive method at concentrations in the range of the 1 mg kg(-1) European regulatory limit.     

Design of wavelength tunable long-period grating couplers based on asymmetric nonlinear dual-core fibers

We demonstrate a grating coupler using an asymmetric nonlinear dual-core fiber with a pair of long-period gratings (LPGs). Simple formulas for the achievement of 100% coupling efficiency and small sidelobes are derived. The passband exhibits steep band transitions. By launching high-intensity optical pumps to alter the refractive indices of the fiber cores through cross-phase modulation, a wavelength tunable LPG dual-core coupler can be realized.     

Measurement of coherent terahertz radiation for time-domain spectroscopy and imaging

A high-power terahertz (THz) source for THz time-domain spectroscopy (THz-TDS) and THz imaging has been developed based on an S-band compact electron linac at the National Institute of Advanced Industrial Science and Technology (AIST). A THz pulse was generated as coherent synchrotron radiation (CSR) from an ultra-short electron bunch and expected to have peak power of kW-order with frequency range of 0.1–2 THz. The electro-optic (EO) sampling method with a ZnTe crystal for the THz pulse measurement has been prepared for THz-TDS system. The timing measurement between the THz pulse and a probe laser was carried out. A preliminary experiment of THz transmission imaging of an integrated circuit (IC) card has been successfully demonstrated using the THz CSR pulse and a W-band rf detector. The imaging result was experimentally compared with a result of X-ray imaging. It is confirmed that its intensity and stability are enough to perform for the THz applications.     

Cover Picture: Reverse‐Selective Microporous Membrane for Gas Separation (Chem. Asian J. 7/2009)

Reverse‐selective membranes , through which bigger molecules selectively permeate, are attractive for developing chemical processes utilizing hydrogen because they can maintain the high partial pressure of hydrogen required for further downstream utilization. Although several of these chemical processes are operated above 473 K, membranes with outstanding reverse‐selective separation performance at these temperatures are still to be reported. M. Matsukata et al. propose a new adsorption‐based reverse‐selective membrane that utilizes a Na cation occluded in a zeolitic framework. The membrane developed in this work enables selective permeation and separation of bigger polar molecules, such as methanol and water, from hydrogen above 473 K. For more information, see their Full Paper on page 1070 ff.

     

Nonstandard arithmetic of iterated polynomials

LetK be an algebraic number field of finite degree andf(X,T) a polynomial overK. For eachφ(X)∈Z[X], we denote byE(φ) the set of all integersa with φ ^m (a) =φ ⁿ (a) for somem≠n. In this paper, we give a condition for a polynomialφ(X)∈Z[X] to satisfy the following; If forn∈N, there existr∈K anda∈Z−E(φ) such thatf r, φ ^m (a)=0, then there exists a rational functiong(X) overK andk∈N such thatf(g(T)), φ ^k (T))=0 .