The Young-Laplace (Y-L) equation describes the difference between inside pressure and outside pressure of a spherical bubble due to surface tension. The Y-L equation is simply deduced from mechanical stability of a bubble, but it is still controversial whether the Y-L equation can be used for tiny bubbles, such as a "nano bubble", because the pressure difference divergently increases as the bubble radius R decreases. We investigated a spherical vapor bubble in Lennard-Jones liquid with molecular dynamics simulation, mainly looking into its mechanical stabilities. We generated a tiny bubble of various size (R 1.7 nm-5 nm in argon unit) under equilibrium conditions by changing the simulation cell size and the number of molecules. The liquid pressure was evaluated with the virial expression, which was negative in general and was found to be strongly dependent on R. The vapor pressure was estimated from the vapor density via an empirical equation of state. The vapor pressure was found to be independent of R and very close to the vapor pressure at bulk liquid-vapor equilibrium. Then we assumed the Y-L equation to calculate the surface tension of the bubble, which turned out to be also independent of R. Thus we confirm that the Y-L equation is valid even for nano-scale bubbles.

S U M M A R YLower to Middle Cretaceous red sandstones were sampled at four localities in the LanpinSimao fold belt of the Shan-Thai Block to describe its regional deformational features. Most of the samples revealed a characteristic remanent magnetization with unblocking temperatures around 680 • C. Primary natures of magnetization are ascertained through positive fold test. A tilt-corrected formation-mean direction for the Jingdong (24.5 • N, 100.8 • E) locality, which is located at a distance of 25 km from the Ailaoshan-Red River Fault, revealed northerly declination with steep inclination (Dec./Inc. = 8.3 • /48.8 • , α 95 = 7.7 • , N = 13). However, mean directions obtained from the Zhengyuan (24.0 • N, 101.1 • E), West Zhengyuan (24.0 • N, 101.1 • E) and South Mengla (21.4 • N, 101.6 • E) localities indicate an easterly deflection in declination; such as Dec./Inc. = 61.8 • /46.1 • , α 95 = 8.1 • (N = 7), Dec./Inc. = 324.2 • /−49.4 • , α 95 = 6.4 • (N = 4) and Dec./Inc. = 51.2 • /46.4 • , α 95 = 5.6 • (N = 13), respectively. The palaeomagnetic directions obtained from these four localities are incorporated into a palaeomagnetic database for the Shan-Thai Block. When combined with geological, geochronological and GPS data, the processes of deformation in the Shan-Thai Block is described as follows: Subsequent to its rigid block clockwise rotation of about 20 • in the early stage of India-Asia collision, the Shan-Thai Block experienced a coherent but southward displacement along the Red River Fault prior to 32 Ma. This block was then subjected to a north-south compressive stresses during the 32-27 Ma period, which played a key role in shaping the structure of Chongshan-Lancang-Chiang Mai Belt. Following this some local clockwise rotational motion has occurred during the Pliocene-Quaternary time in central part of the Shan-Thai Block as a result of internal block movements along the reactivated network of faults.

Optimized geometries and total energies for the 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) molecules were calculated using the Gaussian 92 system of programs at two ab initio MO levels: RHF/6-31G and RHF/6-31G*. In addition to the above levels, the corresponding basis sets, including diffuse function, were also used. The fully-optimized geometry is given for the TCDD molecule. The results were compared and agree closely with the observed structures, which were obtained by X-ray spectrometry. Harmonic vibrational frequencies are calculated at the above-mentioned levels of theory on the basis of the optimized geometries. Comparison with experimental IR results is discussed. It is predicted from vibrational analyses that the butterfly flapping motion of two benzo-planes is a motion having a very low fundamental frequency (3.6 cm -1 ). For those modes which are IR inactive, the predicted Raman frequencies are reported. Some ambiguity concerning the dynamic behavior has also been investigated in terms of the potential energy curve (PEC) as a function of the folding angle (θ), to specify the butterfly flapping motion of the two benzo-planes. It is shown that the potential has little curvature near the minimum. The small curvature of the PEC appears to be consistent with the far-infrared 3.6 cm -1 frequency of the flapping motion.

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We report7 Li pulsed NMR measurements in polycrystalline and single crystal samples of the quasi one-dimensional S = 1 antiferromagnet LiVGe2O6, whose AF transition temperature is TN ≃ 24.5 K. The field (B0) and temperature (T ) ranges covered were 9-44.5 T and 1.7-300 K respectively. The measurements included NMR spectra, the spin-lattice relaxation rate (T −1 1 ), and the spin-phase relaxation rate (T −1 2 ), often as a function of the orientation of the field relative to the crystal axes. The spectra indicate an AF magnetic structure consistent with that obtained from neutron diffraction measurements, but with the moments aligned parallel to the c-axis. The spectra also provide the T -dependence of the AF order parameter and show that the transition is either second order or weakly first order. Both the spectra and the T −1 1 data show that B0 has at most a small effect on the alignment of the AF moment. There is no spin-flop transition up to 44.5 T. These features indicate a very large magnetic anisotropy energy in LiVGe2O6 with orbital degrees of freedom playing an important role. Below 8 K, T −1 1 varies substantially with the orientation of B0 in the plane perpendicular to the c-axis, suggesting a small energy gap for magnetic fluctuations that is very anisotropic.

The electron-density distribution in crystals of CuAIO 2 was investigated on the basis of X-ray intensity data * To whom correspondence should be addressed.0108-7681/83/050564-06501.50 collected by single-crystal diffractometry. The crystal has a delafossite CuFeO 2 structure, containing the Cu ~ ion with linear twofold coordination. Several peaks observed on the difference Fourier maps after the spherical-atom refinement were well explained by assuming aspherical scattering factors of electrons in © 1983 International Union of Crystallography IntroductionThe d ~° ions such as Cu ÷, Ag r, Au ÷ or Hg 2+ have filled d orbitals and, therefore, spherical electron-density distributions are expected for these ions. However, Orgel (1966) proposed the d-s-hybridized orbital model for d l° ions with linear twofold coordinations (e.g. Cu r in cuprite, Cu20). As the energy difference between 3d and 4s orbitals is small, the 3d? orbital whose lobes extend toward the ligands can hybridize with the empty 4s orbital to form hybridized orbitals 1/X/~(d~2-s) and 1/V/2(dz 2 + s).One of the orbitals, 1/V/2(d~2 -s), has no lobe in the direction of the ligands so that the linear coordination can be stabilized by ~e aspherical electron configuration with empty 1/V/2(dz~ + s) and filled 1/v~(d,~ -s) orbitals.Delafossite CuFeO2-type compounds with formula A+B3+O2 have a very anisotropic structure (Fig. 1). It is constructed by the alternate stacking of edge-shared {BO~}oo octahedral layers and A+-ion layers perpendicular to the c axis. Each A r ion is coordinated linearly by two 0 2-ions. The A+ ion is restricted to a d '° or a d 9 ion, while many trivalent cations can enter into the octahedral site. Rogers, Shannon, Prewitt & Gillson (1971) Martin, Rees & Mitschler (1982) studied the chargedensity distribution in Mn2(CO)~ 0 from the X-ray diffraction data and refined the electron populations in the 4s orbital of Mn by the least-squares method for the first time. They obtained the electron configuration 3dS"254s TM, but the value of the 4s population is incorrect, because it exceeds the maximum population. No trial has been reported which deals with the charge-density distributions of transition-metal compounds by taking into account hybridization schemes.The present study shows that the deformation of the electron-density distribution in crystals of CuAIO2 is well explained by assuming d-s hybridization with linear combination of the 3dz~ and 4s orbitals for the valence electrons of the Cu + ion. ExperimentalPolycrystalline CuAIO 2 was prepared by solid-state reaction of Cu20 and A1203 at 1373 K in N 2 atmosphere. The cell dimensions were determined by least-squares procedure from high-angle powder X-ray diffraction data measured at 293 K using Cu K~t radiation; these dimensions are given in the Abstract together with other crystal data, which agree well with previous values (Ishiguro, Kitazawa, Mizutani & Kato, 1981; Ishiguro, Ishizawa, Mizutani & Kato, 1982). D m was measured by a pycnometer.Single crystals of CuAIO 2 w...

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Some TSH receptors (TSHR) on the cell surface cleave into A and B subunits. Cleavage at upstream Site 1 is followed by the proteolytic excision of an intervening C peptide region terminating at a downstream Site 2. Although present evidence suggests that Site 1 lies between amino acid residues 303 and 317, the mechanism and exact amino acid(s) involved in cleavage are unknown. Previous amino acid substitutions at Site 1 failed to abrogate cleavage. We, therefore, performed deletion mutations within this region. Cleavage of cell surface TSHR, detected by 125I-TSH cross-linking to intact cells, was not prevented by deletion of four individual segments within the Site 1 cleavage region (delta305-308, delta309-312, delta313-316, delta317-320). However, deletion of the entire region (delta305-320) reduced the extent of cleavage and shifted the cleavage site upstream of the glycan at amino acid residue N302. Elimination of this glycan (N302Q substitution) reversed the effect of deleting amino acid residues 305-320 on TSHR cleavage, suggesting that reduced cleavage at the new, upstream cleavage site was caused by steric hindrance by the glycan at N302. In summary, deletion, as opposed to mutagenesis, of the TSHR cleavage Site 1 region produces a spatial shift in TSHR cleavage Site 1 from downstream to upstream of the glycan at N302. These observations provide strong evidence that TSHR cleavage at this site does not occur at a particular amino acid motif and suggests that cleavage involves a "molecular ruler" mechanism involving cleavage at a fixed distance from a protease attachment site.