Showing papers by "Sun Yat-sen University published in 1988"

Demographic analysis of insect reproductive levels, patterns and heterogeneity: case study of laboratory strains of three Hawaiian tephritids

Abstract: Reproductive data were collected on individually-held adult oriental fruit flies, Dacus dorsalis, melon flies, Dacus cucurbitae, and Mediterranean fruit flies, Ceratitis capitata including age-by-parity relations, birth interval, frequency distribution of individual egg production levels and the concentration of reproduction among females in a cohort. Specific findings include: i) delay in reproductive peaks in a cohort after eclosion is due almost entirely to the variance in attainment of reproductive maturity among individuals; ii) low reproductive output of reproductively mature melon flies is due mostly to long birth intervals; iii) high egg production in both the medfly and the oriental fruit fly is due to their consistency of egg laying levels and frequency (short birth intervals). Discussion stresses the importance of viewing reproduction, not as a singular and discrete life history trait, but as consisting of subcomponents of daily parity, cumulative parity and birth interval. RESUME Analyse demographique de l'importance, de l'allure et de l'heterogeneite de la reproduction des insectes: etude du cas de trois Tephritidae hawaiennes Les informations sur la reproduction ont ete obtenues a partir d'adultes de Dacus dorsalis, D. Cucurbitae, C. capitata, eleves individuellement. Elles portent sur les parametres suivants: distribution par age en fonction de la fecondite, echelonnement des pontes, distribution des niveaux quotidiens de ponte, frequence des pondeuses par cohorte. Differents caracteres specifiques ont ete mis en evidence: 1) La variabilite de la date d'apparition de la maturite reproductive est pour l'essentiel responsable du retard dans les dates de reproduction maximale; 2) De 30 a 50% des femelles de D. dorsalis agees de 10 jours pondent plus de 50 oeufs/jour pendant les deux semaines qui suivent, tandis que seulement 10 a 20% des femelles des deux autres especes parviennent a pondre cette quantite d'oeufs a n'importe quel age; 3) D. cucurbitae ayant atteint sa maturite pond environ pendant 40% des jours (c.a.d. chaque 2,5 j), tandis que les deux autres especes pondent au moins quelques oeufs pendant 80% des jours (c.a.d. chaque 1,25 j); 4) La production elevee d'oeufs de C. capitata et de D. dorsalis est due a la regularite de leur niveau de ponte et a la frequence (faible espacement); 5) Les fractions des effectifs qui ont pondu au moins 600 oeufs en 30 jours etaient approximativement de 0,8, 0,7, et 0,4 pour D. dorsalis, C. capitata, D. cucurbitae; 6) 50% des femelles de chacune des trois especes contribuent en gros pour 65% a la ponte totale.

STEM study of ferritchromit from the Heng-Chun Chromitite

Abstract: Les etudes de diffraction electronique indiquent que la deviation par rapport a la stœchiometrie spinelle du compose du titre peut raisonnablement s'expliquer par l'intercroissance d'une phase RO dans une spinelle R 3 O 4 , ou R=Fe, Cr, Mg et Al

On the variational principles in linear elastodynamics

Abstract: A new approach is proposed for the systematic derivation of various variational principles in linear elastodynamics. Based on an important integral relation in terms of convolutions given by the authors, the new approach can be used to derive the complementary functionals for the five-field, four-field, three-field, two-field and one-field variational principles more simply and directly. Furthermore, with this approach, it is possible not only to derive the variational principles given by Herrera and Bielak, Oden and Reddy, but also to develop new more general variational principles. And the intrinsic relationship among various principles can be explained clearly.

Global stability for large systems of Volterra-Lotka type integrodifferential population delay equations

Abstract: On considere l'equation integrodifferentielle non lineaire x i (t)=x i (t)[e i +Σ j=1 n p ij x j (t)+Σ j=1 n ∫ o r s ij k ij (θ)x j (t-θ)dθ], i=1, …, n ou 1≤i, j≤n, e i , p ij , s ij sont des constantes. On etudie la stabilite globale de la solution (q 1 , …, q n ) par rapport aux solutions positives

Observations on early and late post-sporozoite tissue stages in primate malaria. V. The effect of pyrimethamine and proguanil upon tissue hypnozoites and schizonts of Plasmodium cynomolgi bastianellii

Abstract: Two rhesus monkeys were each infected with 2·1 × 10 6 sporozoites of Plasmodium cynomolgi bastianellii ; one was treated with 1·0 mg of pyrimethamine base per kg body weight for 5 d after sporozoite inoculation. A further 2 monkeys were each infected with 9·75 × 10 6 sporozoites of the same parasite; one was treated with 10 mg of proguanil per kg body weight for 4 out of 5 d after inoculation. The treated monkeys showed a delayed primary parasitaemia and relapses. In sections of liver biopsies taken 7·5 d after sporozoite inoculation, all monkeys showed numerous hypnozoites. However, there were no full grown schizonts and only rare retarded schizonts in the treated monkeys, in contrast to the untreated monkeys which had many mature or nearly mature schizonts. Later biopsies confirmed the continued presence of hypnozoites in all monkeys.

Bulk and dislocation core diffusion in Al-Mo solid solutions obtained through rapid-solidification processing

Abstract: Samples of Al-2.2at.% Mo and Al-0.7at.% Mo have been prepared as solid solutions by melt-spinning, and have then been annealed at temperatures between 643 and 923 K. Analytical transmission electron microscopy has been used to determine the factors that control the rate of return to equilibrium in these supersaturated solid solutions. It has been found that in the Al-2.2at% Mo alloy the diffusion of Mo, to form the equilibrium phase Al12 Mo, is accompanied by the formation of dislocation networks, which separate regions that contain 2.2 at% Mo from regions of virtually pure Al, where the Mo has been removed from solution. The dislocations accommodate the change in lattice parameter between these two regions and provide diffusion paths to grain boundaries, where Al12 Mo is precipitated. In the case of Al-0.7 at.% Mo it has been found that diffusion occurs either along grain boundaries, during grain growth, or through the bulk of the grains, but that no dislocations are generated during annealing. ...

The pallial organ of Atrina pectinata (Bivalvia: Pinnidae): its structure and function

Abstract: Hitherto, the unique pallial organ of the Pinnidae has been considered to fulfil a cleansing role, removing sediment and shell fragments from the mantle cavity. This study of the pallial organ of Atrina pectinata describes structure in greater detail than before but was unable to demonstrate a cleansing function. Rather, the organ is thigmotropic and massively secretory. Study of the pallial organ head demonstrates it to have a pH of between 2 and 4 and that tall, apparently empty cells in the head epithelium contain sulphuric acid which can be precipitated as barium sulphate crystals following irrigation with barium chloride. Acid-secreting cells are recorded from a number of animal groups, notably opisthobranch gastropods, where they are concluded to possess a defensive function. Such a structure has not hitherto been recorded from the Bivalvia.

Copolymerization of ethylene and butadiene with supported titanium catalyst

Abstract: The copolymerization of ethylene and butadiene with a supported titanium catalyst (TiCl4/MgCl2/EB/Φ2SiCl2/AlEt3) is described. The resulting products were characterized by IR, 13C-NMR, x-ray diffraction, differential thermal analysis, electron microscopy, and solvent extraction. It was found that the butadiene units are substantially in trans-1,4 configuration and blocked sequences. Both ethylene and butadiene blocks form crystalline phases. The presence of unsaturated bonds made it possible to graft MMA and maleic anhydride. The influences of monomer composition, temperature, Al/Ti ratio, catalyst concentration, and solvents on the copolymerization were investigated.

The topological Markov chain

Abstract: The topological Markov chain or the subshift of finite type is a restriction of the shift on an invariant subset determined by a 0, 1-matrix, which has some important applications in the theory of dynamical systems. In this paper, the topological Markov chain has been discussed. First, we introduce a structure of the directed gragh on a 0, 1-matrix, and then by using it as a tool, we give some equivalent conditions with respect to the relationship among topological entropy, chaos, the nonwandering set, the set of periodic points and the 0, 1-matrix involved.

Raman spectra of KNSBN crystals at the ferroelectric-paraelectric phase transition

Abstract: Raman spectra of KNSBN single crystals with different compositional ratios of Sr/Ba and K/Na have been measured. The limited softening of a lattice mode v 2 and the gradual disappearance of another lattice mode v 4 are verified as the most important features related to the ferroelectric-paraelectric phase transition in this system.

[Epithelioid sarcoma--immunohistochemical and ultrastructural study].

Abstract: Five cases of epithelioid sarcoma are reported, of which four were studied by immunohistochemistry and one by electron microscopy. Immunohistochemically, the results of cytokeratin showed that these four cases were positive to different degrees by polyclonal cytokeratin and three out of four revealed positive results with low molecular weight cytokeratin monoclonal antibody. Two cases were positive with carcinoembryonic antigen and the other two were negative. The immunohistochemical stain was helpful for differential diagnosis from other sarcomas, such as malignant fibrous histiocytoma and rhabdomyosarcoma. By electron microscopy, tumor cells could be divided into light and dark cells which possessed more or less cell organelles, intermediate microfilaments in the cytoplasm and numerous pinocytic vesicles lying along the cell membrane. The occasional presence of poorly developed desmosomes or the absence of tonofibril bundles and glandular structures can rule out the diagnosis of carcinoma. One of these cases was originally diagnosed as metastatic carcinoma to the skin by light microscopy, which was refuted by electron microscopy, and the keratin positive reaction by immunohistochemistry was helpful for the diagnosis of epithelioid sarcoma. Therefore, the authors suggest that immunohistochemical and electron microscopic studies be used for diagnosing difficult cases of epithelioid sarcoma. From our observation, we consider that the cells of epithelioid sarcoma may derive from undifferentiated mesenchymal cells possessing the potentials of differentiating into synovioblasts, histiocytes or fibroblasts.

Fe-57 Mössbauer effect studies of some ancient Chinese pottery from xudun

Abstract: 18 Sherds (4500 B.C.–4000 B.C.) unearthed from different archaeological layers at the same place were studied by Mossbauer spectroscopy. The original firing atmosphere can be deduced from the ratio of the Fe2+ to Fe3+. By comparing the Mossbauer parameters of the original and the refired sherds, we can assess the original firing temperatures.

Spin distribution in 3,4-dithiacyclobutene (dithiete) radical cation

Abstract: Huckel and ab initio (STO-3G) calculations confirm the experimental assignment of the 3,4-dithiacyclobutene (dithiete) radical cation as a π radical with a SOMO symmetric to a plane bisecting the C[sbnd]C and S[sbnd]S bonds. However, neither calculation is in good agreement with the low value of p c≅0.1 observed experimentally.

Hyperfine field distribution in electrodeposited iron-nickel alloys

Abstract: The distribution of hyperfine fields in f.c.c. electrodeposited iron-nickel alloys with composition ranging from 10 to 27 at% Fe has been studied from the observed Mossbauer spectra using a method of analysis developed by Hesse and Rubartsch. The different I2,5/I1,6 values for the different parts of the same component sample indicate that the distribution of the electrical field in bath plays an important role in the spin preferred orientation within electrodeposited layer. The asymmetry in the width of Mossbauer lines has been discussed.

Crystal structure of a non-stoichiometric channel inclusion complex of 1-benzyl-6-phenylpiperidin-2-one-5-carboxylic acid with acetonitrile

Abstract: C19H19NO3·x CH3CN (x=0.3),Mr=643.35, hexagonal, space groupP61 (No. 169),a=23.027(5),c=5.775(1) A,V=2652(1) A3,Z=6. The structure was solved by direct methods and refined toR=0.077 for 1562 observed MoKα reflections. The title heterocyclic carboxylic acid was established as thetrans isomer, with the phenyl and carboxyl substituents occupying pseudo-equatorial and equatorial positions, respectively, of the piperidin-2-one ring in a half-chair conformation. Acid host molecules related by the 61 screw operation are linked by intermolecular O−H...O (cyclic amide) hydrogen bonds to generate an open channel bounded by coaxial intertwined helices each having a pitch of 5c. Within each channel of free diameterca. 6.0 A the acetonitrile molecules partially occupy highly disordered sites which do not lie on thec axis.

Mössbauer studies on ancient chinese pottery of Yangshao Culture Period

Abstract: Eleven pieces of ancient Chinese pottery (4770 B.C. – 2960 B.C.) of Yangshao Culture Period collected from the Xi'an area have been studied by means of Mossbauer spectroscopy. The samples were refired up to 1100°C in steps of 100°C for 2h in air. The highest temperature up to which the Mossbauer pattern remains basically unchanged can be identified with the original firing temperature. The result indicates that the firing temperatures for most of the sherds were between 900–1000°C. The function of the grit contained in the pottery has been discussed. The crimson and reddish painted materials on the surface of sherds have been studied, respectively. The first appearance of pottery can probably be traced back to an even earlier period.

Dynamic response analysis of marine power systems

Abstract: A computer simulation method for predicting the dynamic responses of a marine power system containing both AC and DC subsystems is proposed. The method has two important features. First, it allows modelling of system components in modular form and representation of network relations by utilising Kirchhoff's current law, hence providing flexibility in model building and testing. The second feature is its ability to simulate the performance of DC machines and converters in a combined AC/DC system. The paper contains a description of the method and its application to a practical marine power system. Simulation results are practically verified by comparing with a manufacturer's supplied experimental data.

The internal strain effect onTc in the YBaAlCu oxide superconductor

Abstract: The ceramics with the composition of YBa2Cu3(1−x)Al3xO9−n (0 ≦ x ≦ 0.55) are synthesized directly by the general ceramic manufacture. Stable high-Tc superconductivity with a resistive midpoint temperature of 103 K and zero resistance temperature of 102 K is observed in YBa2Cu3(1−x)Al3xO9−n with x = 4.6 mol% ceramic samples. The enhancement of Tc with decreasing lattice ratios a/c and b/c is observed. The experimental result of enhanced Tc can be explained by an internal lattice strain caused by a chemical pressure, which occurs owing to Al doping into YBaCuO ceramics. Es werden Keramiken mit der Zusammensetzung YBa2Cu3(1−x)Al3xO9−n (0 ≦ x ≦ 0.55) mit Hilfe des ublichen keramischen Verfahrens hergestellt. Eine stabile Hoch-Tc-Superleitung mit einer Widerstands-Mittelpunktstemperatur von 103 K und einer Null-Widerstandstemperatur von 102 K wird fur YBa2Cu3(1−x)Al3xO9−n-Proben mit x = 4,6 mol% beobachtet. Es wird eine Erhohung von Tc mit abnehmenden Gitterparameterverhaltnissen a/c und b/c gefunden. Die Erhohung von Tc kann erklart werden durch innere Gitterverspannungen durch chemischen Druck, der infolge von Al-Dotierung in YBaCuO-Keramiken auftritt.

The photochromic behavior of viologens and polyviologens in polymer matrices

Abstract: The photochromic behavior of viologens (V2+) and polyviologens (PV2+) was investigated using poly(N-vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) as matrices. In the PVP matrix the coloration rate of butylviologen bromide increases with decreasing humidity, but no influence of humidity on coloration rate was observed in the PVA matrix. The coloration rate in the PVA matrix follows a second-order plot while in the PVP matrix it does not. These results imply that, for the coloration process of viologens in polymer matrices, the effect of the matrix polymer as an electron donor must be considered. The fading rate of colored poly(butylviologen bromide) in PVP matrix increases remarkably with humidity. The fading reaction obeys a first-order relation at the very beginning and permits the determination of the rate constant. The fading rate increases with temperature with an activation energy of 13 kcal/mol. The fatigue of viologens and polyviologens was evaluated by the half-decay flash number...

Mössbauer study of amorphous Fe40Ni40PxB20−x

Abstract: The hyperfine field distributions of amorphous Fe40Ni40PxB20−x (x=10, 12, 14, 17) samples before and after different heat treatments have been determined by means of Mossbauer spectroscopy. All of these P(H) curves are characterized by a main high field maximum and an additional low field maximum, respectively. The asymmetry of distributions of high field component in P(H) of Fe40Ni40PxB20−x increases progressively from Fe40Ni40P10B10 to Fe40Ni40P17B3. The distributions of low field component in P(H) are affected differently by the annealing temperature. The results indicate that the phospoorus element plays an important role in the hyperfine interactions of amorphous Fe40Ni40PxB20−x The influence of annealing atmosphere has been discussed.

Determination of molecular and crystal structures of a unique new tetraterpenoid——methyl sartortuoate

Abstract: A unique new tetracyclic tetraterpenoid has been isolated from the Chinese soft coral Sarcophyton tortuosum Tixier-Durivault and designated as methyl sartortuoate. Its chemical and crystal structures as well as its absolute configuration were determined by IR, UV, NMR and X-ray diffraction analysis. The authors have also suggested a possible route for its biogenesis.

Influences on HCN laser frequency by the parameters of the laser

Abstract: The influences on HCN laser frequency by the parameters of the laser have been discussed theoretically and experimentally. The frequency variations of the HCN laser versus discharge current and gas pressure have been measured to be 2.9 kHz/mA and 8.1 kHz/mtorr respectively. The experimental results have been explained theoretically.