Phase diagram of growth mode for the SiGe/Si heterostructure system with misfit dislocations

The strain, surface and interface energies of the SiGe/Si (SiGe grown on Si) heterostructure system with and without misfit dislocations were calculated for the Frank–van der Merwe (FM), Stranski–Krastanov (SK) and Volmer–Weber (VW) growth modes essentially based on the three kinds of fundamental and simple structures. The free energies for each growth mode were derived from these energies, and it was determined as a function of the composition and layer thickness of SiGe on Si. By comparison of the free energies, the phase diagrams of the FM, SK and VW growth modes for the SiGe/Si system were determined. The (1 1 1) and (1 0 0) reconstructed surfaces were selected for this calculation. From the phase diagrams, it was found for the growth of SiGe on Si that the layer-by-layer growth such as the FM mode was easy to be obtained when the Ge composition is small, and the island growth on a wetting layer such as the SK mode was easy to be obtained when the Ge composition is large. The VW mode is energetically stable in the Ge-rich compositional range, but it is difficult for the VW mode to appear in the actual growth of SiGe on Si because the VW region is right above the SK region. The regions of the SK and VW modes for the (1 1 1) heterostructure are larger than those for the (1 0 0) one because the strain energy of the (1 1 1) face is larger than that of the (1 0 0) face. The regions of the SK and VW modes for the heterostructure with misfit dislocations are narrower than those for the one without misfit dislocations because the strain energy is much released by misfit dislocations. The phase diagrams roughly explain the behavior of the FM and SK growth modes of SiGe on Si.     

Synthesis and pharmacological evaluation in mice of halogenated cannabidiol derivatives

Six halogenated derivatives of cannabidiol (CBD, 1) substituted on the aromatic ring at the 3' and/or 5' position, 3'-chloro- (2), 3',5'-dichloro- (3), 3'-bromo- (4), 3',5'-dibromo- (5), 3'-iodo- (6) and 3',5'-diiodo-CBD (7) were synthesized and their pharmacological effects of barbiturate-induced sleep prolongation, anticonvulsant effects and locomotor activity were evaluated by intravenous (i.v.) injection in mice. 2 (10 mg/kg, i.v., 69 +/- 10 min) significantly prolonged pentobarbital-induced sleeping time by 3.1-fold, compared to control (22 +/- 2 min), although other 1 derivatives used did not significantly affect the sleeping time. 2, 4 and 6 (10 mg/kg, i.v.) significantly prolonged hexobarbital-induced sleeping time by 2.0-, 2.0- and 2.3-fold, respectively, compared with control (52 +/- 5 min). On the other hand, 1 and all halogenated derivatives did not significantly prolong barbital-induced sleeping time. The monohalogenated derivatives, 2, 4 and 6 were able to prolong pentobarbital and hexobarbital-induced sleeping time, although the dihalogenated derivatives, 3, 5 and 7 did not exhibit a prolongation of the sleeping time. All halogenated derivatives of 1 except for brominated derivatives (2, 3, 6, 7) tended to prolong tonic seizure latency induced by pentylenetetrazol. 1 and its halogenated derivatives did not exhibit any prolongation of seizure latency induced by picrotoxin or strychnine. Maximal electroshock test demonstrated that 1 and 4 exhibited almost the same potency in their anticonvulsant effects, although other 1 derivatives 2, 3, 5, 6 and 7 did not show significant effect up to a dose of 63 mg/kg, i.v. The ED50 values (mg/kg, i.v.) of 1 and 4 were 38 and 44, respectively. 1 and 4 also showed anticonvulsant effect in minimal and maximal electroshock-threshold tests. 2, 4 and 6 tended to decrease the total distance (horizontal activity) and number of rearings (vertical activity) of mice, whereas 3, 5 and 7 tended to increase the number of rearings. However, the effects of all derivatives were not statistically significant from the control. 2 and 4 were the most potent derivatives on pharmacological activities among the synthetic cannabinoids examined in the present study. These results indicate that monohalogenation of 1 leads to some modification of the pharmacological profile of CBD.     

Phase diagram calculation for epitaxial growth of GaInAs on InP considering the surface, interfacial and strain energies

In order to know the effects of the surface, interfacial and strain energies on the calculation of the phase diagram, these energies were calculated for the Ga_xIn_1−xAs/InP structure and the Ga–In–As ternary phase diagram for the epitaxial growth of GaInAs on (1 1 1) InP was determined. The layer-thickness dependence of the liquidus temperature and solidus composition was determined. It was found that the liquidus and solidus phases were strongly influenced by these energies when the layer thickness was thinner than about 0.06 μm. The consideration of the effects of the surface, interfacial and strain energies is effective to explain the peculiar behavior of the experimental results near the lattice-matched composition (x=0.47), which is called the latching effect.     

Observation of a topological and parity-dependent phase of m = 0 spin states

A Ramsey interrogation scheme was used to measure the phase shift of laser-cooled 87Rb clock-transition pseudospins arising as a result of a reversal of a bias-magnetic field, i.e., B--> -B, during the interrogation. While no phase shift occurred when the reversal was sudden, the Ramsey fringes were shifted by a factor of pi when the reversal was adiabatic. We thus verified the prediction that the spin states |F,m=0 acquire a purely topological and parity-dependent phase factor of (-1)F as a result of B--> -B.     

Minimum number of edges in graphs that are both P2- and Pi-connected

A simple graph with n vertices is called P_i-connected if any two distinct vertices are connected by an elementary path of length i. In this paper, lower bounds of the number of edges in graphs that are both P₂- and P_i-connected are obtained. Namely if $\text{i?}\text{1}\text{2}\text{(n+1)}$, then |E(G)|?((4i?5)/(2i?2))(n?1), and if $\text{i >}\text{1}\text{2}\text{(n+ 1)}$, then |E(G)|?2(n?1) apart from one exeptional graph. Furthermore, extremal graphs are determined in the former.     

Some oscillation theorems for a class of quasilinear elliptic equations

Oscillation criteria are obtained for quasilinear elliptic equations of the form (E)below. We are mainly interested in the case where the coefficient function oscillates near infinity. Generalized Riccati inequalities are employed to establish our results.     

Quenching of photoluminescence from GaAs/AlGaAs single quantum well by an electric field at high temperature

Photoluminescence measurements at room temperature and at liquid nitrogen temperature on a GaAs/AlGaAs single quantum well structure subject to an electric field are performed to study (i) the photoluminescence quenching and (ii) the shift in the photoluminescence energy induced by the field. The observed shifts in the luminescence energies are explained successfully in terms of the field induced electron-hole separation model. For the quenching of the luminescence intensities, more work, particularly on nonradiative processes, is required to clarify the mechanism.     

Infrared absorption spectra and compositions of evaporated silicon oxides (SiOx)

Clear and simple relationships among oxygen content, peak position in the 9–10 μm region and intensity of infrared absorption were obtained for a wide range of x value in evaporated silicon oxides (SiO_x). Using these relationships, the origin of 875 cm⁻¹ peak was proposed to be due to a vibrational mode from a structural combination of Si---(O_ySi_4-y) (y = 2, 3 and 4).     

Inorganic chemical approaches to pharmacognosy. VII. X-ray fluorescence spectrometric studies on the inorganic constituents of crude drugs. (5). The relationship between inorganic constituents of plants and the soils on which they are grown

Inorganic constituents of the leaves of several kinds of plants growing on different soil types were investigated using energy-dispersive X-ray fluorescence spectrometry. The results can be summarized as follows: (1) Each plant exhibited a characteristic metals profile, even if they were grown on similar soil types. (2) As we would expect, the metals profile of the plant leaves depends on the inorganic constitution of the soil on which it is grown. However, the degree of the influence of the soil types on the metals profile of the plant differs according to the kind of inorganic element: Ca and Cu are almost independent of the soil types, but the Ti and Fe content is dependent upon the soil types. (3) Sr content of plant leaves is closely related to the ratio of Sr to Ca of the soil on which the plants are grown. (4) This information should be helpful in identifying the producing district or original plant of a crude drug by its metals profile.     

Fabrication of dialkyldimethylammonium/vanadium oxide gel hybrid Langmuir-Blodgett membranes

A hybrid Langmuir-Blodgett (LB) membrane of dialkyldimethylammonium (DCnA, n=12?18) and vanadium oxide gel was fabricated by compressing a DC _n A monolayer on an aqueous vanadium oxide solution. The vanadium oxide gel effectively aggregated in situ as a monolayer on the LB trough and stabilized the ammonium monolayer by electrostatic interaction. The hybrid LB monolayer, transferred onto a silicon wafer, had a smooth surface, with less than 1-nm roughness over a 1 μm × 1 μm square area. Multilayered membranes, prepared by repeated transfer of monolayers, showed sharp XRD patterns, assigned as an ordered bilayer-type structure with 2.9–4.8 nm thickness.