Subpicosecond photon echoes by using nanosecond laser pulses

Subpicosecond time resolutions have been obtained in photon echoes when a sample was excited by two nanosecond dye laser pulses with a smooth and broad spectrum. The dye laser was pumped by second harmonics of a Q-switched Nd:YAG laser, and the pulse width was 10 ns. The sample was 3% Nd³⁺-doped silicate glass, and the center frequency of the dye laser was tuned at 5910 Å on resonance with the ⁴I_{$\text{9}\text{2}$} ? ²G_{$\text{7}\text{2}$}, ⁴G_{$\text{5}\text{2}$} transition of Nd³⁺. The homogeneous transverse relaxation time T₂ was measured to be 91 ps at 10 K in agreement with the previous measurements by picosecond pulses.     

A new synthesis of olefins. Conversion of nitroolefins into olefins by reductive elimination

A nitro group in nitroolefins is displaced by hydrogen giving the corresponding olefins in good yields by the reaction of nitroolefins with sodium sulfide in the presence of benzenethiol. It proceeds rapidly at room temperature.     

Microwave spectroscopy of the CCl radical

The CCl radical was generated by a dc glow discharge in CCl₄, and rotational transitions of C³⁵Cl in both ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ were observed in the mm-wave region by using a source modulation microwave spectrometer. From an analysis of the observed spectra the magnetic and electric quadrupole hyperfine coupling constants of the ³⁵Cl nucleus were determined precisely. The Λ-doubling constant p₀ was determined to be positive, indicating that unknown ²Σ^? excited electronic states are making dominant contributions to the Λ doubling in the ground state. The previous diode-laser result [J. Mol. Spectrosc.85, 416–426 (1981)] was reanalyzed by using improved wavelength standards and by fixing the ground-state parameters to the present microwave values including the B₀ rotational constant 20 797.1725(38) MHz. The vibration-rotation constant α^B and the equilibrium bond length r_e were thus determined to be 0.006 768 2(48) cm^?1 and 1.645 218(16) Å, respectively, with 2.5 times standard deviations in parentheses. The spin density on the chlorine atom was estimated to be about 0.20 from the observed hyperfine coupling constants.     

Synthesis of lipid A analogues containing glucose instead of glucosamine and their LPS-antagonistic activities

Lipid A analogues containing glucose in substitution for glucosamine on the reducing end were synthesized, and the inhibitory activities on LPS-induced TNFα production (LPS-antagonistic activity) in vitro using human whole blood cells were measured. The IC₅₀ values (nM) of these ten compounds, 8, 14, 21, 31, 40, 51, 57, 62, 67 and 72, were 11.2, 15.4, 2.7, 0.1, 0.4, 1.3, 3.2, 3.2, 1.4 and 14.4, respectively. And also inhibitory activities (ID₅₀) on TNFα production toward galactosamine loaded C3H/HeN mice in vivo of compounds 21, 31, 57, 62 and 67 were measured. The values of these compounds were 0.29, 0.50, 0.61, not dose-dependent and 0.33 mg/kg, respectively.     

Ferrielectric dielectric behaviour and the nature of phase transition of ammonium sulphate

Phenomenological treatments of ferrielectrics are made in terms of two non-equivalent sublattice polarizations in the paraelectric phase. Unlike the Curie-Weiss behaviour of usual proper ferro- and antiferro-electrics, the dielectric susceptibility does not depend linearly on temperature. Particularly in the case of a first order phase transition, the Curie-Weiss constant seems to be unusually small. As an example, the dielectric properties of (NH₄)₂SO₄, which was known to be a peculiar ferroelectric, is discussed from the ferrielectric point of view. The true Curie-Weiss constant is of a comparable order of magnitude to that of the order-disorder ferroelectric.