Synthesis of New (Pyrimido[4,5-e][1,3,4] thiadiazin-7-yl)hydrazine Derivatives

New (pyrimido[4,5-e][1,3,4]thiadiazin-7-yl)hydrazines were synthesized via the cyclocondensation of alkyl-2-phenylhydrazinecarbodithioates as bidentate nucleophiles with 5-bromo-2,4-dichloro-6-methylpyrimidine as an electrophile and further replacement of chlorine atom on the seven number position of pyrimido[4,5-e][1,3,4]thiadiazin by hydrazine in boiling ethanol.     

Sonochemical synthesis of novel pyrano[3,4-e][1,3]oxazines: A green protocol

The atom-efficient and green protocol for formation of pyrano[3,4-e][1,3]oxazines utilizing dimethyl carbonate under ultrasound irradiation in a presence of KF/basic alumina was reported. We provide a novel series of pyrano[3,4-e][1,3]oxazine derivatives interesting for biological screening tests. In general, it was found that ultrasound irradiations enable the reactions to occur which could not be carried out under silent conditions. These remarkable effects appeared in sonicated reactions can be reasonably interpreted in terms of acoustic cavitation phenomenon. Structures of the products were established on analytical and spectral data. This protocol offers several advantages attain many principles of green chemistry including, save energy, atom economy, clean reactions, inexpensive green reagent and use catalysts rather than stoichiometric reagents.     

非退化Cauchy-Riemann流形上(-e)b复形的正则性

对于余维数大于1的CR流形M上的一点ξ, M在ξ附近的CR结构可由两步幂零Lie群Gξ的CR结构来逼近.Gξ随ξ变化而变化.M上的(-e)由两步幂零Lie群上的(-e)b和(-e)b逼近.用两步幂零Lie群上(-e)解构造非退化CR流形M上(-e)b的拟基本解,并定义M上的拟距离.(-e)b和(-e)b复形的正则性可从M上的调和分析得到.     

Sub-coercive field dynamic hysteresis in morphotropic phase boundary composition of Pb(Zr1/2Ti1/2)O3-Pb(Zn1/3Nb2/3)O3 ceramic and its scaling behavior

Sub-coercive field dynamic ferroelectric hysteresis of a morphotropic phase boundary composition of the PZT-PZN ceramic was investigated under influence of the compressive stress. The scaling relation of hysteresis area 〈A〉 against frequency f, field amplitude E₀, and stress σ took a form of , which is not different significantly to that of other PZT-PZN compositions with pure tetragonal or rhombohedral structure, as well as to that of soft and hard PZT bulk ceramics. This study suggested that the domain structures, not ceramic compositions, played a key role in controlling dynamic hysteresis behavior of ferroelectric materials.     

High repetition rate planar laser induced fluorescence of OH in a turbulent non-premixed flame

Received: 1 February 1999 / Revised version: 17 February 1999     

Mobility and conductivity of ionic and bonded defects in hydrogen-bonded chains with nonlinear interactions

The proton conductivity and the mobility arising from motions of the ionic and bonded defects, in hydrogen-bonded molecular systems are investigated by means of the quantum mechanical method. Our two component model goes beyond the usual classical harmonic interaction by inclusion of a quartic interaction potential between the nearest-neighbor protons. Among the rich variety of soliton patterns obtained in this model, we focus our attention to compact kink (kinkon) solutions to calculate analytically, the mobility of the kinkon-antikinkon pair and the specific electrical-conductivity of the protons transfer in the hydrogen-bonded systems under an externally applied electrical-field through the dynamic equation of the kinkon-antikinkon pair. For ice, the mobility and the electrical conductivity of the proton transfer obtained are about 5.307×10^-7 m²  V^-1  s^-1 and 6.11×10^-4 Ω^-1 m^-1, respectively. The results obtained are in qualitative agreement with experimental data.     

Alpha-induced fragmentation of 28Si in a statistical model

Within the context of a statistical model, that incorporates final-state interaction between a pair of fragments, we have calculated the energy spectra associated with the production of different isobaric pairs as a function of their lab kinetic energy and isobaric and elemental distributions of nuclei produced in the ⁴He$ + $²⁸Si reaction at cm incident energies of 102.7, 173.7, 300, 500, and 1000MeV. Double differential cross-section of isobars 16, 20, and 24 as a function of their lab kinetic energies at 30^° and the same for isobar 24 at 10^°, 30^°, 60^°, and 90^° have been calculated at cm incident energies of 102.7 and 173.7MeV and compared with the data of Woo et al. Calculated yields follow the trend of the data at each angle, and calculated angular distributions also reproduce the general trend of the observed ones. A key feature of the model is that it allows for fragments to be emitted in ground states as well as in excited states that are allowed by the conservation of energy. The analysis establishes that the fragments are emitted in excited state. The excitation energies for A = 24 and 16 are deduced from the data. The observed angular distributions for A = 7, 12, 16, 20, 24, and 28 are well accounted for assuming them to be emitted in excited states. The relative production probabilities for different elements and isobars are energy dependent. The yields for unstable elements, ⁵Li, ⁸Be, and ²⁶Al, are found to be significant. The relative fragmentation probabilities of all allowed isotopic pairs have been presented.     

Incomplete ferroelectricity in SrTi 18O 3

Motivated by recent experiments demonstrating suppression of ferroelectricity with pressure in SrTi¹⁸O₃, the dynamics of the phase transition mechanism are reinvestigated within a nonlinear polarizability model. For temperatures far above the phase transition polar micro domains are formed which increase in size with decreasing temperature to freeze out at T_c without forming long range order. Experimentally, soft mode dynamics are simultaneously observed, evidencing that displacive and order/disorder features coexist. In the ferroelectric phase both components persist whereby an incomplete and inhomogeneous ferroelectric state is formed.     

Synthesis and optical properties for crystals of a novel organic semiconductor [ Ni(Cl) 2{(Ph 2P) 2CHC(R 1R 2)NHNH 2}]

In this investigation, the synthesis process of the apyrazole derivative for diphenylphosphino-methane hydrazine complexes [ Ni(Cl)₂{(Ph₂P)₂CHC(R₁R₂)NHNH₂}] was reported, and the obtained crystals were analyzed by X-ray diffraction. As a result of the growth process, a set of complexes were formed. The structures of these complexes are discussed on the basis of Elemental analysis (EA), IR, ¹H-NMR, ³¹P-NMR spectroscopic data and FAB mass spectra. The compound under investigation shows typical semiconductor behavior as a result of delocalization of the π-electrons in the structure. The reflectance and transmittance spectra for the crystals were measured and analyzed in the incident photon energy range 1.29 to 3.93 eV and in the temperature range 77 to 300 K. The optical study revealed that the optical transition is direct allowed. Below the absorption edge, the refractive index as a function of wavelength was determined in the low energy region of the used incident photon energy range. From the refractive index-wavelength variations, the oscillator and dispersion energies of the refractive index for the obtained crystals were determined. The static refractive index and static dielectric constant were evaluated.     

Investigation of a Tabletop Confocal Micro X-Ray Fluorescence Setup

A new tabletop confocal micro x-ray fluorescence setup with an MCBM 50-0.6B x-ray tube is assembled. The confocal micro x-ray fluorescence setup includes two lenses, a polycapillary full lens in the excitation channel and a polycapillary half lens in the detection channel. A Ni-Cr wire in diameter 25μm is used to investigate the FWHM of three-dimensional confocal volume. A basso-relievo capital letter of a 1-jiao RMB coin of 2005 version is studied with this confocal micro x-ray fluorescence setup.