Showing papers by "Nanjing University published in 1990"

Spatial Patterns of Atmosphere-Ocean Interaction in the Northern Winter.

Abstract: The variability of monthly mean sea-surface temperature (SST) anomalies over the extratropical North Atlantic and Pacific and its relation to atmospheric circulation anomalies over the Northern Hemisphere during wintertime is investigated, by applying eigenvector analysis to a 39-year dataset and correlating the time series of the resulting expansion coefficients with the hemispheric 500 mb height and sea-level pressure fields. In agreement with previous studies, the simultaneous correlation between the tone series of the expansion coefficient of the first empirical orthogonal function (EOF 1) of North Pacific sea surface temperature (SST) and the hemispheric 500 mb height field resembles the Pacific/North American pattern, and the corresponding pattern for Atlantic SST resembles the North Atlantic Oscillation. In the vicinity of the conters of action of thew patterns, the SST fluctuations associated with these modes explain on the order of half the variance of 500 mb height and slightly less of ...

Existence of invariant tori in three-dimensional measure-preserving mappings

Abstract: In this paper, we formulate and prove the existence theorem of invariant tori which persist under nonlinear perturbations in some three-dimensional measure-preserving mappings.

Theory of the Single Ion Magnetocrystalline Anisotropy of 3d Ions

Abstract: Methods for calculating the single ion magnetocrystalline anisotropy of 3d ions in the crystal field with threefold axis or higher symmetry and lower symmetry are given. Using these methods, the contributions of Fe3+ ions at all the five crystal sites of Ba-ferrite (BaM) to the magnetocrystalline anisotropy constants and their temperature dependence are calculated. Also calculated is the single ion anisotropy of the Co2+ ion substituting the Fe3+ ion at the 12k site. The results agree well with experiments. Methoden zur Behandlung der Einionenanisotropie von 3d-Ionen im Kristallfeld mit einer dreifachen Achse oder hoheren und niedrigeren Symmetrie werden dargelegt. Mittels dieser Methoden werden die Beitrage der Fe3+-Ionen fur alle funf verschiedenen Gitterplatze in Barium-Ferrit (BaM) zur magnetokristallinen Anisotropiekonstante und ihrer Temperaturabhangigkeit berechnet. Die Einionenanisotropie des Co2+-Ions, das die Fe3+ Ionen am 12k Gitterplatz substituiert, wird ebenfalls berechnet. Die Resultate stimmen mit den Experimenten gut uberein.

Harmonic generations in an optical Fibonacci superlattice.

Abstract: An optical Fibonacci superlattice has been proposed to produce the second-harmonic generation and the third-harmonic generation, which is the sum frequency of the second-harmonic and the fundamental frequency in the same material. Because of the quasiperiodicity of the optical Fibonacci superlattice, the phase mismatches of the optical parametric processes caused by the frequency dispersion of the refractive index can be compensated with the reciprocal vectors which the optical Fibonacci superlattice provides. A theory which analyzes the second-harmonic generation and the third-harmonic generation processes in the material and the calculations applied to the optical Fibonacci superlattice made from a single ${\mathrm{LiNbO}}_{3}$ crystal is presented in detail. The calculations show that the efficiencies of the second-harmonic generation and the third-harmonic generation are comparable to, or even larger than, those obtained with commonly used phase-matching methods.

Second-harmonic generation in a Fibonacci optical superlattice and the dispersive effect of the refractive index

Abstract: A Fibonacci optical superlattice is analyzed which is made from a single crystal with quasiperiodic laminar ferroelectric domain structures. The second-harmonic generation in this system is studied. Because of the dispersive effect of the refractive index, the second-harmonic spectrum does not reflect the symmetry of the quasiperiodic structure and thus does not exhibit self-similarity. The existence of the extinction phenomenon constitutes one major difference between our system and heterostructure systems. A general extinction rule is also obtained.

On the Sitnikov Problem

Abstract: A mapping which reflects the properties of the Sitnikov problem is derived. We study the mapping instead of the original differential equations and discover that there exists a hyperbolic invariant set. The theoretical prediction of the disorder region agrees remarkably with numerical results. We also discuss the LCEs and KS-entropy of the dynamical system.

Solving minimax problems by interval methods

Abstract: Interval methods are used to compute the minimax problem of a twice continuously differentiable functionf(y, z),y e ℝ m ,z e ℝ n ofm+n variables over anm+n-dimensional interval. The method provides bounds on both the minimax value of the function and the localizations of the minimax points. Numerical examples, arising in both mathematics and physics, show that the method works well.

Raman measurement of the grain size for silicon crystallites

Abstract: Etude par diffusion Raman des echantillons de a-Si:B:H prepares par la methode CVD, en utilisant des temperatures de depot et des niveaux de dopage differents. Interpretation des resultats experimentaux en termes de la mesure de la taille du grain des cristallites de silicium

The role of the c-fms oncogene in the regulation of HL-60 cell differentiation.

Abstract: Human promyelocytic leukemia HL-60 cells were induced to differentiate into macrophages by PMA (phorbol 12-myristate-13-acetate), 1-alpha-25-(OH)2D3(1-alpha-25-dihydroxyvitamin D3, hrGM-CSF (human recombinant granulocyte-macrophage colony-stimulating factor) and into granulocytes by DMSO (dimethylsulfoxide). We found that the differentiation of HL-60 cells into macrophages was accompanied by transcription of the c-fms oncogene, which was assessed by a modified PCR (polymerase-chain reaction) method. After treatment with a c-fms anti-sense oligomer, the PMA and hrGM-CSF induced macrophage differentiation of HL-60 cells was significantly inhibited, whereas either 1-alpha-25-(OH)2D3 induced macrophage or DMSO and hrGM-CSF induced granulocytic differentiation was not inhibited. Furthermore, we treated the HL-60 cells with M-CSF (macrophage-colony stimulating factor or CSF-1) anti-sense N degrees 2 (see Figure 1) in the presence of PMA, hrGM-CSF, 1-alpha-25-(OH)2D3 and DMSO. The results showed that this treatment leads to a significant inhibition of PMA and hrGM-CSF-induced macrophage differentiation, but has no influence on the 1-alpha-25-(OH)2D3-induced macrophage differentiation and DMSO-induced granulocytic differentiation. It was further demonstrated that the M-CSF (or CSF-1) and c-fms antisense oligomers acted synergistically on inhibition of macrophage formation induced by PMA and hrGM-CSF, but had no inhibitory effect on the macrophage formation induced by 1-alpha-25-(OH)2D3. Thus we concluded firstly, that HL-60 cells differentiate into macrophages along two different pathways: one is involved in the action of the c-fms oncogene and the other is not. Secondly, an autocrine circuit of M-CSF (or CSF-1) action may exist in the macrophage formation induced by PMA and hrGM-CSF.

Magnetic and mössbauer study of rare-earth-substituted M-, W- and X-type hexagonal ferrites

Abstract: The effects of substitution of Ba2+ ions for some trivalent rare-earth ions on the magnetic properties and phase formation of M-, W- and X-type hexaferrites are studied. The compounds considered were: Ba1-REx/2Nax/2Fe12O19 with RE = gadolinium, lanthanum, lutetium, samarium and 0.0 ⩽x ⩽ 0.3; Ba0.9La0.05Na0.05Zn2Fe16O27 and Ba1.9La0.05Na0.05Zn2Fe28O46. The samples were prepared by standard ceramic procedures and have been investigated by thermomagnetic analysis, X-ray diffraction, Mossbauer spectroscopy, scanning electron microscope and magnetic measurements. Monophasic BaREx/2-M compounds were found for 0.0⩽x<0.2 giving an indication of the solubility range of the rare-earth (RE) atoms in this phase. The intrinsic magnetic properties and the coercive field are lowered with the exception of the lanthanum-substituted hexaferrite. No significant differences in the phase formation and magnetic properties were observed for the W- and X-type hexaferrites.

Structural instability in high-T c superconducting oxides

Abstract: Two broad internal friction (attenuation as well) peaks in YBCO measured at around 120 K and 250 K are found to exhibit the characteristics of a first-order phase transition. X-ray diffraction indicates no symmetry change on cooling from room temperature but only a downward jump of the lattice parameters was observed. This is referred to as a phase-like transition (PLT) and further confirmed by stress-strain, specific heat and Debye-Waller factor measurements. There always occurs a phase-like transition at 10-30 K above T c in YBCO, BSCCO and TBCCO which disappears in the non-superconducting phases. Ultrasonic studies on single-crystal BSCCO reveal a pronounced elastic anisotropy in the c-plane and a velocity minimum associated with PLT. The overall trend of elastic stiffening below room temperature and some discrepancies and questions in elasticity measurements so far observed for high-T c oxides have been explained or clarified in terms of an abnormal fast change of lattice parameters.

Complex-induced coupling effect: adhesion of some polymers to copper metal promoted by benzimidazole

Abstract: Improved adhesion of a polymer with polar functional groups to copper has been achieved by pretreating the copper surface with benzimidazole solution. The adhesion strength was found to increase by two to three times. The coupling mechanism and interfacial structure of the copper-polymer composite have been investigated by X-ray photoelectron and Fourier transform infrared relection-absorption spectroscopies. We found that benzimidazole reacted with copper metal in the presence of oxygen to form benzimidazolato copper(+1), which covered the surface in the form of a thin polymeric layer. As the surface was exposed to air, some of the cuprous cations were oxidized to cupric ions. When poly(vinylpyridine) was coated onto the pretreated surface, the nitrogen atoms of the side groups of the polymer chains co-ordinated to the cupric cation to form interfacial bonding connecting the polymer to the copper metal.

A note to the concept of derivatives on local fields

Abstract: In this note, we present expressions of characters on a local field Kq, including p-series fields, p-adic number fields and their algebraic extensions. Then we define (p)-type derivative for a function fon Kq and evaluate the pointwise derivative of a character χ of K q + .

Existence of periodically invariant curves in 3-dimensional measure-preserving mappings

Abstract: With the aid of a normal form of a family of measure-preserving mappings in dimension 3, which is deduced in this paper, we prove that there are periodically invariant curves which survive the nonlinear perturbations in the generic case.

Influence of a small addition of nd on the magnetic properties of amorphous fe-b alloys

Abstract: The influence of the addition of a few atomic percent of Nd on the Curie temperature, crystallization temperature, and magnetic properties of amorphous iron-boron alloys was investigated. With increasing Nd content, the crystallization temperature increases linearly, but the Curie temperature and the magnetic moment of the Fe atom decrease. The change of the crystallization temperature and the magnetic properties of amorphous Nd{sub {ital x}}Fe{sub 81}B{sub 19{minus}{ital x}} (0{le}{ital x}{le}6) alloys can be explained by the atomic size effect and the chemical properties of neodymium. On annealing, the coercivity {ital H}{sub {ital c}} and the magnetic energy ({ital BH}){sub max} of the samples (except {ital x}=0) increase, depending strongly on the Nd concentration. A hard magnet with {ital H}{sub {ital c}}=2.3 kOe and ({ital BH}){sub max}=8 MG Oe was obtained.

Ultrasonic study of structural instability of monocrystalline and polycrystalline Bi-Sr-Ca-Cu-O

Abstract: Two internal-friction (attenuation) peaks around 95 and 130 K in the polycrystal and single crystal of Bi-Sr-Ca-Cu-O are found to be related to the superconducting transition at 84 and 107 K, respectively. The jump of lattice parameter and shape-memory effect occurring at the peak temperatures reveal the characteristics of a martensitic transition. The velocity and attenuation versus temperature of ultrasonic longitudinal waves propagating along two directions in the a-b plane at 10\ifmmode^\circ\else\textdegree\fi{} to the a and b axes and of [010] shear waves with [100] polarization were measured for the ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ single crystals. The anisotropic elasticity in the c plane is manifested. Only the longitudinal waves in a direction and the shear waves show an obvious softening minimum of velocity around 250 K, which is associated with an attenuation peak due to a phaselike transition, but other longitudinal waves reveal a monotonic stiffening from room temperature down to ${\mathit{T}}_{\mathit{c}}$. The origin of the overall trend of elastic stiffening that appears in the measurements so far for high-${\mathit{T}}_{\mathit{c}}$ oxides is discussed.

Hair casts: a clinical and electron microscopic study

Abstract: Hair casts were seen in 22 girls ranging in age from 4 to 13 years. They were localized to the frontal, vertex, and temporal areas. The number of affected hairs varied from one-tenth to one-third. Twenty of the 22 girls styled their hair in ponytails or pigtails. Compound root sheath casts were present in six of nine patients using 1% 4-dimethylaminocinamaldehyde stain. A mass of large polymorphous scales and solitary or clumped spores was seen on the surface of hair casts using scanning and transmission electron microscopy. Energy-dispersive x-ray microanalysis showed that elements of silicon, aluminum, and molybdenum were uniquely present in hair casts. We assume that tightly drawn braids, by causing local circulatory disturbances and inflammation of the scalp, may be one etiologic factor in the disorder.