Paraneoplastic neurologic syndromes. 2. Lambert-Eaton myasthenic syndrome. 1) The molecular structure of calcium channel and immunology

The effect of divalent cations on the inactivation of Escherichia coli by high hydrostatic pressure was investigated. The presence of 0.5 mmol l-1 of CaCl2, MgCl2, MnCl2 and FeCl2 reduced pressure inactivation of E. coli MG1655, while 0.5 mmol l-1 of ZnCl2, NiCl2, CuCl2 and CoCl2 increased inactivation. Baroprotection by Ca2+ was found to be dose-dependent up to at least 80 mmol l-1 and was studied in more detail in terms of inactivation kinetics. Logarithmic survivor plots against time deviated from first order kinetics, suggesting that MG1655 cultures were heterogeneous with regard to pressure resistance. All cultures were shown to contain a small proportion of cells that were only slowly inactivated. Addition of Ca2+ increased the proportion of these tolerant cells in the cultures up to 1000-fold at 80 mmol l-1, but did not affect their inactivation rate. The addition of EDTA resulted in the opposite effect, lowering the proportion of pressure-tolerant cells in the cultures. Three pressure-resistant mutants of E. coli MG1655 were found to be more resistant to EDTA under pressure compared with MG1655, and were unaffected by Ca2+ under pressure. In addition, these mutants had a 30-40% lower Ca2+ content than MG1655. Based on these results, it is postulated that pressure killing of E. coli MG1655 is mediated primarily by the destabilization of Ca(2+)-binding components, and that the mutations underlying pressure resistance have resulted in pressure-stable targets with reduced Ca(2+)-binding affinity.     

New catalytic functions of Pd–Zn, Pd–Ga, Pd–In, Pt–Zn, Pt–Ga and Pt–In alloys in the conversions of methanol

Pd and Pt supported on ZnO, Ga₂O₃ and In₂O₃ exhibit high catalytic performance for the steam reforming of methanol, CH₃OH+H₂OCO₂+3HH₂, and the dehydrogenation of methanol to HCOOCH₃, 2CH₃OHHCOOCH₃+2HH₂. Combined results with temperature-programmed reduction (TPR) and XRD method revealed that Pd–Zn, Pd–Ga, Pd–In, Pt–Zn, Pt–Ga and Pt–In alloys were produced upon reduction. Over the catalysts having the alloy phase, the reactions proceeded selectively, whereas the catalysts having metallic phase exhibited poor selectivities.     

Dispersion of SiC in Aqueous Media with Al2O3 and Y2O3 as Sintering Additives

It has been well accepted that polyethylene imine (PEI) is an effective dispersant for silicon carbide (SiC) in aqueous media. However, after the addition of sintering additives (Al₂O₃ and Y₂O₃), this dispersing effect is reduced significantly. In this work, a second dispersant, citric acid, was used to resolve this problem. It was found that citric acid could decrease the slurry viscosity (without sintering additives) and enhance the PEI adsorption on SiC particle surface. The optimal amount of citric acid required to achieve a minimum viscosity for 55 vol% SiC suspensions was equal to ∼0.87 wt% (at pH ∼6.8). With the aid of citric acid, well-stabilized SiC suspensions (containing sintering additives) were realized, which exhibited slight shear thinning rheologies. After tape casting and SPS sintering, dense SiC samples were obtained with a homogeneous fine-crystalline microstructure. Results showed that citric acid was an effective dispersant for improving the dispersion of SiC particles containing sintering additives.     

Magnetic Correlation in BETS2(Cl2TCNQ)

We carried out⁷⁷Se NMR measurements on BETS₂(Cl₂TCNQ) under pressure in order to investigate the magnetic properties of the insulating state which appears above 0.6 GPa. The relaxation rate 1/T₁ at 0.7 GPa shows small peak-like anomaly at 20 K, indicating a spin density wave transition as observed in BETS₂(Br₂TCNQ).     

11B NMR Study of Pure and Lightly Carbon-Doped MgB2 Superconductors

We report a¹¹B NMR line shape and spin-lattice relaxation rate (1/(T ₁ T)) study of pure and lightly carbon-doped MgB_2−x C _x forx=0, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB₂ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase ofH _c ^2/c with carbon doping with respect to pure MgB₂. The spin-lattice relaxation rate 1/(T ₁ T) demonstrates clearly the presence of a coherence peak right belowT _c in pure MgB₂, followed by a typical BCS decrease on cooling. However, at temperatures lower than ≈10 K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon-doped systems both the coherence peak and the BCS temperature dependence of 1/(T ₁ T) weaken, an effect attributed to the gradual shrinking of the σ hole cylinders of the Fermi surface with electron doping.     

11B NMR Study of Pure and Lightly Carbon-Doped MgB2 Superconductors

We report a ¹¹B NMR line shape and spin-lattice relaxation rate (1/(T₁T))(1/(T_1T)) study of pure and lightly carbon-doped MgB_2-xC_x_{2-x}{\rm C}_x for x = 0,0.02x = 0,0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB₂_2 exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of H^c_c2H^c_{c2} with carbon doping with respect to pure MgB₂_2. The spin-lattice relaxation rate 1/(T₁T)1/(T_1T) demonstrates clearly the presence of a coherence peak right below T_cT_{\rm c} in pure MgB₂_2, followed by a typical BCS decrease on cooling. However, at temperatures lower than ?\approx 10 K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon-doped systems both the coherence peak and the BCS temperature dependence of 1/(T₁T)1/(T_1T) weaken, an effect attributed to the gradual shrinking of the σ hole cylinders of the Fermi surface with electron doping.