Current transport property in GdBCO coated conductor with artificial pinning centers in a wide range of temperature,magnetic field up to 27 T,and field angle

We have investigated current transport property in Gd₁Ba₂Cu₃O_7−δ coated conductor with artificial pinning centers in a wide range of temperature, magnetic field, B up to 27 T, and field angle. Due to the additional c-axis correlated pins, critical current density, J_c in B//c was enhanced and the improvement was observed in wide range of B. On the other hand, around B⊥c below 65 K, the angular dependence of n-value showed a valley-like behavior, although the J_c was increasing. In addition, the temperature dependence of the pinning force density defined as J_c × B was not scaled on an expected master curve. These results indicate the pinning in B⊥c is governed by different mechanism below 65 K and high magnetic field.     

Self-compensation of third-order dispersion for ultrashort pulse generation demonstrated in an Yb fiber oscillator

Compensation of the intracavity dispersion in the mode-locked oscillator is known to be one of the most important factors for ultrashort pulse generation. However, recent investigations of a Yb-doped fiber mode-locked oscillator revealed that precise third-order dispersion (TOD) compensation is not always necessary for ultrashort pulse generation, owing to the strong nonlinearity that compensates residual TOD without reducing its spectral bandwidth. The origin of the nonlinear TOD compensation has remained unclear. To investigate the process in detail, we studied the pulse evolution inside a 30 fs Yb-doped fiber mode-locked oscillator both experimentally and numerically, and we found that the nonlinear phase shift with a temporally asymmetric pulse shape introduces an appropriate amount of TOD that exactly cancels the residual cavity dispersion.     

Five cases of beta-ureidopropionase deficiency detected by GC/MS analysis of urine metabolome

The clinical presentation of inborn errors of pyrimidine degradation varies considerably from asymptomatic to severe neurological illness. We have reported a method to screen for and make a chemical diagnosis of beta-ureidopropionase deficiency, leading to the discovery of the first asymptomatic case of this disease. In this method, the recovery of beta-ureidopropionate and beta-ureidoisobutyrate, the key biomarkers, was very high,and the adoption of GC/MS and targeted analysis enabled us to simultaneously obtain information related and unrelated to pyrimidine metabolism. The present study reports the results of a large-scale screening of 24,000 newborns using dried urine on filter paper. Identification of a total of four asymptomatic patients among newborns suggests the high incidence (1/6000) of this disease in Japan. While these newborns were asymptomatic, two additional cases detected at the age of 5 years as well as 3 months with this method for high-risk screening had autism and West syndrome, respectively.The key biomarkers and alpha-ureidobutyrate used as an internal standard were found to give not only their di-trimethylsilyl derivatives but also tri-trimethylsilyl derivatives, upon derivatization. The mass spectra and retention times of their tri-trimethylsilyl derivatives and data handling for quantification of the markers are presented.Identification of individuals with defects in pyrimidine metabolism would realize personalized medication in cancer chemotherapy with pyrimidine analogs such as 5-fluorouracil.     

Asymmetric Suzuki–Miyaura Coupling in Water with a Chiral Palladium Catalyst Supported on an Amphiphilic Resin

You oughta use water : Broad functional‐group (FG) tolerance was observed for the title coupling of aryl halides (X=Cl, Br, I) and aryl boronic acids to give biaryl compounds with up to 94 % ee. The chiral imidazoindole phosphine–palladium catalyst supported on an amphiphilic polystyrene–poly(ethylene glycol) (PS–PEG) resin could be recycled readily.

     

Uracil as Nucleating Agent for Bacterial Poly[(3‐Hydroxybutyrate)‐co‐(3‐hydroxyhexanoate)] Copolymers

In this study, uracil has been introduced as the nucleating agent (NA) for bacterially synthesized poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyhexanoate)] (PHBHHx) copolymers with HHx content of 5, 10, 18 mol‐%, and poly(3‐hydroxybutyrate) (PHB) homopolymer for the first time. Its effect was compared with the conventional NA of PHB, that is, boron nitride (BN), and two other naturally occurring pyrimidine derivatives, i.e., thymine and cytosine. The effects of uracil on the crystallization kinetics, melting behavior, spherulite morphology, and crystalline structure of PHBHHx and PHB were investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide‐angle X‐ray diffraction (WAXD). Uracil and BN exhibit the comparable nucleation efficiency on the crystallization of PHB, whereas uracil shows much more effective nucleation ability than BN for PHBHHx copolymers. With incorporation of 1 wt.‐% uracil, PHBHHx with 0–10 mol‐% HHx units can finish crystallization upon cooling at 10 °C · min^?1. The crystallization half‐times (t_1/2) of all the PHB and PHBHHx samples decrease significantly with presence of uracil. The crystallization rate of polymers further enhances with increase in uracil concentration. With addition of 1 wt.‐% uracil, the t_1/2 value of PHBHHx with 10 mol‐% HHx units melt‐crystallizing at 80 °C decreases to ≈4.0% of the neat polymer, and the nucleation density increases by 3–4 orders of magnitude. The incorporation of uracil has no discernable effect on the crystalline structure of PHBHHx, as evidenced by WAXD results. It was proposed that the nucleation mechanism of the uracil/PHBHHx (or PHB) system might be the epitaxial nucleation.

     

On waiting time distributions associated with compound patterns in a sequence of multi-state trials

In this article, waiting time distributions of compound patterns are considered in terms of the generating function of the numbers of occurrences of the compound patterns. Formulae for the evaluation of the generating functions of waiting time are given, which are very effective computational tools. We provide several viewpoints on waiting time problems associated with compound patterns and develop a general workable framework for the study of the corresponding distributions. The general theory is employed for the investigation of some examples in order to illustrate how the distributions of waiting time can be derived through our theoretical results. This research was partially supported by the ISM Cooperative Research Program (2006-ISM·CRP-2007).     

Enantiocontrolled synthesis of the epoxycyclohexenone moieties of scyphostatin, a potent and specific inhibitor of neutral sphingomyelinase

The epoxycyclohexenone moieties 2 and 3b of scyphostatin (1), a potent and specific inhibitor of neutral sphingomyelinase, were synthesized in enantiomerically pure forms starting from (−)-quinic acid (11). The synthetic method features (i) the preparation of the olefin masked enones 25 and 29, the precursors for the key aldol-type coupling reaction, (ii) the efficient and stereocontrolled aldol-type coupling reactions between 25 (or 29) and benzaldehyde (8) and Garner's aldehyde analogue 9 to deliver alcohols 23 and 24, respectively, both of which possess the requisite asymmetric quaternary carbon center at the C6 position, and (iii) the stereospecific S_N2-type epoxide ring formation of the mesylates 35 and 47 under mild basic conditions to produce the targeted compounds 2 and 3b, respectively.     

Characterization of host-guest complexes of cucurbit[n]uril (n = 6, 7) by electrospray ionization mass spectrometry

When an intramolecular cavity exists in a molecule, it can trap another chemical species to form a host-guest complex. We examine the formation of such an inclusion complex with cucurbit[n]uril (CBn, n = 6, 7) as the host to trap alkali metal or ammonium ions as the guest, by electrospray ionization mass spectrometry (ESI-MS). The results show that the inclusion complexes are formed between the three-dimensional cylinder of CBn hosts and the guest cations. Selectivity of the complex formation is dependent both on (1) ion-dipole interactions between the cylindrical portal of the CBn hosts and the guest cations and (2) the hydrophobic interactions at the inner cavity of CBn.     

Development of septum-free injector for gas chromatography and its application to the samples with a high boiling point

A novel apparatus with a simple structure has been developed for introducing samples into the vaporizing chamber of a gas chromatograph. It requires no septum due to the gas sealing structure over the carrier gas supply line. The septum-free injector made it possible to use injection port temperatures as high as 450 degrees C. Repetitive injection of samples with boiling points below 300 degrees C resulted in peak areas with relative standard deviations between 1.25 and 3.28% (n=5) and good linearity (r(2)>0.9942) for the calibration curve. In the analysis of polycyclic aromatic hydrocarbons and a base oil, the peak areas of components with high boiling points increased as the injection port temperature was increased to 450 degrees C.