bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismic evidence for dehydration embrittlement of the subducting Pacific slab
Authors: Mishra O. P. , Zhao Dapeng
Published: May 2004

We determined a fine 3‐D P‐wave velocity structure of the subducting Pacific slab by inverting a large number of high‐quality P‐arrival times to better understand the genesis of the 26 May 2003 Miyagi‐oki earthquake (Mw 7.0) and its aftershock sequence, which occurred within the subducting Pacific slab beneath northeast (NE) Japan. Lateral and depth‐ward heterogeneities are imaged up to several tens of kilometers beneath the upper boundary of the subducting slab. The main shock and its aftershocks occurred in a distinct zone characterized by a lower velocity anomaly than its surroundings within the slab. The reduced velocity anomaly within the slab is attributed to the process of dehydration embrittlement resulting from the dehydration of hydrous minerals in the subducting Pacific slab, which may have induced the main shock and its aftershock sequence by enhancing pore pressures along the pre‐existing faults/fractures in the subducting slab beneath the NE Japan forearc region.
Electrodynamics of a flux transfer event: Experimental test of the Southwood model
Authors: Marchaudon A. , Cerisier J.‐C. , Greenwald R. A. , Sofko G. J.
Published: May 2004

On 12 September 1999, a conjunction between two SuperDARN radars and the Ørsted satellite gave, for the first time, simultaneous access to the ionospheric convection enhancement and the field‐aligned currents (FACs) associated with a Flux Transfer Event. The radars observed an azimuthally elongated convection flow burst and the Ørsted satellite observed a series of successive small‐scale parallel currents alternating between downward and upward. The most poleward pair of currents, whose directions were in agreement with the Southwood model, was observed when Ørsted crossed the front edge of the flow burst. A quantitative comparison of the current density of each FAC and of the Pedersen current density indicates that the closure current for this FACs pair occurred inside the flow burst, confirming the validity of the Southwood model. The Poynting flux carried by the parallel currents was less than 1% of the power carried by the solar wind plasma.
Statistical study of thin current sheet evolution around substorm onset
Authors: Asano Y. , Mukai T. , Hoshino M. , Saito Y. , Hayakawa H. , Nagai T.
Published: May 2004

The spatial distribution of current sheet thinning in the substorm growth phase is examined statistically using Geotail data. The current density is calculated from the ion and electron velocity moments. It is found that the current sheet becomes thin before the onset mainly on the Earthward side of the initial near‐Earth neutral line (NENL) position and becomes less than 0.5 RE on average. However, on the tailward side of the NENL position, the current sheet becomes thin only after the onset. This result implies that the NENL forms at or near the tailward edge of the thin current sheet. An intense current sheet is formed in the center of the plasma sheet on average, but the largest current density is temporarily observed in the off‐neutral sheet region, indicating the formation of a double‐peaked current sheet. The current carriers becomes mainly electrons in the thin current sheet under the existence of the ambipolar electric field directed toward the neutral sheet.
High‐Light Stress and Photoprotection in Umbilicaria antarctica Monitored by Chlorophyll Fluorescence Imaging and Changes in Zeaxanthin and Glutathione
Authors: Barták M. , Hájek J. , Vráblíková H. , Dubová J.
Published: May 2004

Abstract: The effect of high light on spatial distribution of chlorophyll (Chl) fluorescence parameters over a lichen thallus (Umbilicaria antarctica) was investigated by imaging of Chl fluorescence parameters before and after exposure to high light (1500 μmol m‐2 s‐1, 30 min at 5 °C). False colour images of FV/FM and ΦII distribution, taken over thallus with 0.1 mm2 resolution, showed that maximum FV/FM and ΦII values were located close to the thallus centre. Minimum values were typical for thallus margins. After exposure to high light, a differential response of FV/FM and ΦII was found. The marginal thallus part exhibited a loss of photosynthetic activity, manifested as a lack of Chl fluorescence signal, and close‐to‐centre parts showed a different extent of FV/FM and ΦII decrease. Subsequent recovery in the dark led to a gradual return of FV/FM and ΦII to their initial values. Fast (30 min) and slow (1 ‐ 22 h) phase of recovery were distinguished, suggesting a sufficient capacity of photoprotective mechanisms in U. antarctica to cope with low‐temperature photoinhibition. Glutathione and xanthophyll cycle pigments were analyzed by HPLC. High light led to an increase in oxidized glutathione (GSSG), and a conversion of violaxanthin to zeaxanthin, expressed as their de‐epoxidation state (DEPS). The responses of GSSG and DEPS were reversible during subsequent recovery in the dark. GSSG and DEPS were highly correlated to non‐photochemical quenching (NPQ), indicating involvement of these antioxidants in the resistance of U. antarctica to high‐light stress. Heterogeneity of Chl fluorescence parameters over the thallus and differential response to high light are discussed in relation to thallus anatomy and intrathalline distribution of the symbiotic alga Trebouxia sp.
Direct and Indirect Climate Change Effects on Photosynthesis and Transpiration
Authors: Kirschbaum M. U. F.
Published: May 2004

Abstract: Climate change affects plants in many different ways. Increasing CO2 concentration can increase photosynthetic rates. This is especially pronounced for C3 plants, at high temperatures and under water‐limited conditions. Increasing temperature also affects photosynthesis, but plants have a considerable ability to adapt to their growth conditions and can function even at extremely high temperatures, provided adequate water is available. Temperature optima differ between species and growth conditions, and are higher in elevated atmospheric CO2. With increasing temperature, vapour pressure deficits of the air may increase, with a concomitant increase in the transpiration rate from plant canopies. However, if stomata close in response to increasing CO2 concentration, or if there is a reduction in the diurnal temperature range, then transpiration rates may even decrease. Soil organic matter decomposition rates are likely to be stimulated by higher temperatures, so that nutrients can be more readily mineralised and made available to plants. This is likely to increase photosynthetic carbon gain in nutrient‐limited systems. All the factors listed above interact strongly so that, for different combinations of increases in temperature and CO2 concentration, and for systems in different climatic regions and primarily affected by water or nutrient limitations, photosynthesis must be expected to respond differently to the same climatic changes.
MECRIS: A compact ECRIS for ionization of noble gas radioisotopes at ISOLDE
Authors: Wenander F. , Lettry J. ,   the ISOLDE Collaboration
Published: May 2004

A very compact Electron Cyclotron Resonance Ion Source (ECRIS) for singly charged radioactive gases has been developed at ISOLDE/CERN. The radioisotopes are produced by fission, spallation, and fragmentation reactions induced via high-energy protons impacting on a thick target. The often short-lived radioactive elements required for ISOLDE physics diffuse out of the target, effuse through a transfer tube, and eventually reach the ionizing volume. An efficient ionization process is mandatory in view of the very small production cross sections of radioactive elements far from stability and fast ionization is desired to minimize decay losses. The MECRIS (Mono ECR ISOLDE) is intended for light noble gases (He, Ne, Ar, and Kr), which have low ionization efficiency in ordinary plasma ion sources, but also for gaseous molecular compounds of C, N, and O isotopes. We will report on the design and construction of the device, including magnetic field calculations and rf simulations. Results of the first tests performed with stable ion beams are presented.
Extraction design and low energy beam transport optimization of space charge dominated multispecies ion beam sources
Authors: Delferrière O. , De Menezes D.
Published: May 2004

In all accelerator projects, the low energy part of the accelerator has to be carefully optimized to match the beam characteristic requirements of the higher energy parts. Since 1994 with the beginning of the Injector of Protons for High Intensity (IPHI) project and Source of Light Ions with High Intensities (SILHI) electron cyclotron resonance (ECR) ion source development at CEA/Saclay, we are using a set of two-dimensional (2D) codes for extraction system optimization (AXCEL, OPERA-2D) and beam transport (MULTIPART). The 95 keV SILHI extraction system optimization has largely increased the extracted current, and improved the beam line transmission. From these good results, a 130 mA D+ extraction system for the International Fusion Material Irradiation Facility project has been designed in the same way as SILHI one. We are also now involved in the SPIRAL 2 project for the building of a 40 keV D+ ECR ion source, continuously tunable from 0.1 to 5 mA, for which a special four-electrode extraction system has been studied. In this article we will describe the 2D design process and present the different extraction geometries and beam characteristics. Simulation results of SILHI H+ beam emittance will be compared with experimental measurements.
Review of laser ion sources developments in Prague and production of q over 50+ ions at Prague Asterix Laser System (invited)
Authors: Láska L. , Jungwirth K. , Králiková B. , Krása J. , Krouský E. , Mašek K. , Pfeifer M. , Rohlena K. , Skála J. , Ullschmied J. , Badziak J. , Parys P. , Ryć L. , Szydlowski A. , Wolowski J. , Woryna E. , Ciavola G. , Gammino S. , Torrisi L. , Boody F. P.
Published: May 2004

The high-power iodine laser systems PERUN and Prague Asterix Laser System, with a maximum attainable laser intensity IL of up to about 6×1016 W/cm2, were used to generate highly charged ions of various elements (Al,Co,Ni,Cu,Ag,Sn,Ta,W,Pt,Au,Pb,Bi). The properties of ions were investigated mainly on the basis of time-of-flight method using ion collectors, cylindrical electrostatic ion energy analyzer, Thomson parabola spectrometer, and track detectors. Simultaneous x-ray and interferometric measurements were also implemented. Maximum ion charge states of heavy ions above z=50+ were recorded and the maximum energy of emitted ions exceeded Ei=22 MeV. Using laser intensities of about 1×1016 W/cm2 can produce such ions. Due to the convenient pulse length of the iodine laser, part of the pulse may interact with the self-created expanding plasma. It was proved that in this case the conditions for an appearance of the relativistic self focusing may be fulfilled (position of minimum focus spot in front of the target surface and the threshold laser intensity about 3×1014 W/cm2) and the highest charge states above 50+ may be generated, too.
Heavy ion beam injection systems for fusion plasma diagnostics
Authors: Bondarenko I. S. , Chmyga A. A. , Dreval N. B. , Khrebtov S. M. , Komarov A. D. , Kozachek A. S. , Krupnik L. I. , Eliseev L. G. , Melnikov A. V. , Perfilov S. V.
Published: May 2004

This article presents long-focus ion beam injection systems developed for investigation of plasma parameters by heavy ion beam probing diagnostics in fusion devices. Ion beam parameters vary in a wide range of both beam intensity of alkali probing ions (1–100 μA) and initial energy (20–300 keV), determined by the experimental claims on each plasma device under study. This article describes the characteristics of beam extraction systems with transport ion optics and control, and accelerator power supplies with high stability (not worse than 10−5). Presented systems allow us a fine tuning of the beam focusing along the beam trajectory in plasmas studied. They provide an accurate spatial resolution of measurements in plasma of modern fusion devices up to 5 mm.
Broad beam low-energy ion source for ion-beam assisted deposition and material processing
Authors: Kotov D. A.
Published: May 2004

The double-anode ion source has been developed for high-current ion-beam application. Ion generating process results in a circulating of electron current in crossing E×H fields in the annular acceleration region. Volt–ampere and discharge characteristics at different configurations of magnetic field directions in the discharge region were investigated. The ion source generates an ion beam, with the energy in the range from 40 to 1000 eV, using rare and active gases. Beam current over 1 A have been obtained at mean ion energies 40–300 eV. This ion source should be useful in the applications where larger currents of low-energy ions are used, especially, for thin film deposition: to increase adhesion, modify stress, increase density or hardness, produce the preferred orientation, and to improve step coverage. It should also be useful for cleaning and etching. Double anode ion source suited for use in a production environment because it is mechanically rugged and reliable. Ion source can operate with filament or the plasma bridge neutralizer.
Initial stage of flat plate impact onto liquid free surface
Authors: Iafrati Alessandro , Korobkin Alexander A.
Published: May 2004

The liquid flow and the free surface shape during the initial stage of flat plate impact onto liquid half-space are investigated. Method of matched asymptotic expansions is used to derive equations of motion and boundary conditions in the main flow region and in small vicinities of the plate edges. Asymptotic analysis is performed within the ideal and incompressible liquid model. The liquid flow is assumed potential and two dimensional. The ratio of the plate displacement to the plate width plays the role of a small parameter. In the main region the flow is given in the leading order by the pressure-impulse theory. This theory provides the flow field around the plate after a short acoustic stage and predicts unbounded velocity of the liquid at the plate edges. In order to resolve the singular flow caused by the normal impact of a flat plate, the fine pattern of the flow in small vicinities of the plate edges is studied. It is shown that the initial flow close to the plate edges is self-similar in the leading order and is governed by nonlinear boundary-value problem with unknown shape of the free surface. The Kutta conditions are imposed at the plate edges, in order to obtain a nonsingular inner solution. This boundary-value problem is solved numerically by iterations. At each step of iterations the “inner” velocity potential is calculated by the boundary-element method. The asymptotics of the inner solution in both the far field and the jet region are obtained to make the numerical algorithm more efficient. The numerical procedure is carefully verified. Agreement of the computed free surface shape with available experimental data is fairly good. Stability of the numerical solution and its convergence are discussed.
Finite-volume optimal large-eddy simulation of isotropic turbulence
Authors: Zandonade Paulo S. , Langford Jacob A. , Moser Robert D.
Published: May 2004

The feasibility of an optimal finite-volume large-eddy simulation (LES) model for isotropic turbulence is evaluated. This modeling approach is based on the approximation of the ideal LES by a stochastic estimate of the fluxes in a finite-volume representation of the Navier–Stokes equation. Stochastic estimation of the fluxes allows for the simultaneous treatment of Navier–Stokes, discretization and subgrid effects, yielding a compact, yet accurate scheme for the large eddy simulation of isotropic turbulence. Both global and local models based on optimal finite-volume LES are developed and used in a priori tests guiding the choice of stencil geometry and model inputs. The most promising models in the a priori exams are tested in actual simulations (i.e., a posteriori) and the results compared with those for filtered direct numerical simulation (DNS) and the dynamic Smagorinsky model. The a posteriori performance of the optimal finite-volume LES models, evaluated by the energy spectrum and third-order structure function, is superior to that of the dynamic Smagorinsky model on a coarse grid. While applicability to other cases is currently limited by the dependence of the present approach on DNS statistical data, research is underway to remove this requirement.
On the Leibniz bracket, the Schouten bracket and the Laplacian
Authors: Coll Bartolomé , Ferrando Joan Josep
Published: May 2004

The Leibniz bracket of an operator on a (graded) algebra is defined and some of its properties are studied. A basic theorem relating the Leibniz bracket of the commutator of two operators to the Leibniz bracket of them is obtained. Under some natural conditions, the Leibniz bracket gives rise to a (graded) Lie algebra structure. In particular, those algebras generated by the Leibniz bracket of the divergence and the Laplacian operators on the exterior algebra are considered, and the expression of the Laplacian for the product of two functions is generalized for arbitrary exterior forms.
Self-focusing and channel-coupling effects on short laser pulses propagating in a plasma channel
Authors: Jha Pallavi , Wadhwani Navina , Upadhyaya Ajay. K. , Raj Gaurav
Published: May 2004

Nonparaxial, nonlinear propagation of a relativistic laser pulse in a preformed plasma channel having a parabolic density profile is analyzed. Nonlinearity arises due to relativistic motion of plasma electrons and their coupling with plasma channel. The effect of nonlinearities on betatron oscillations is analyzed and the nonlinear critical channel depth required for propagation of a matched laser pulse is evaluated. Mismatch due to nonlinear effects and additional condition for matched pulse propagation are obtained. Amplitude of the matched, as well as mismatched, beam is derived and finite pulse effects are studied.
Generation of silicon nanoparticles via femtosecond laser ablation in vacuum
Authors: Amoruso S. , Bruzzese R. , Spinelli N. , Velotta R. , Vitiello M. , Wang X. , Ausanio G. , Iannotti V. , Lanotte L.
Published: May 2004

We demonstrate that femtosecond laser ablation of silicon targets in vacuum is a viable route to the generation and deposition of nanoparticles with radii of ≈5–10 nm. The nanoparticles dynamics during expansion has been analyzed through their structureless continuum optical emission, while atoms and ions, also present in the plume, have been identified by their characteristic emission lines. Atomic force microscopy analysis of the material deposited at room temperature has allowed the characterization of the nanoparticles size distribution. Taking into account the emissivity of small particles we show that the continuum emission is a blackbody-like radiation from the nanoparticles. Our results suggest that nanoclusters are generated as a result of relaxation processes of the extreme material state reached by the irradiated target surface, in agreement with recently published theoretical studies.
Infrared-laser-induced periodic surface structure in azo-dye polymer
Authors: Ivanov Mario , Rochon Paul
Published: May 2004

Second-harmonic and third-harmonic waves that are generated in an azo-polymer form diffraction patterns without any material deformation. The source is a single IR laser beam at λ=1064 nm that is weakly absorbed by the polymer. If the IR power is sufficiently high, laser-induced periodic (700 nm) structures grow on the polymer surface and give rise to distinctive diffraction patterns in the visible and ultraviolet. If the IR power is low, there are no surface changes but diffraction patterns that have the same shape still appear.
Organic field-effect transistors with nonlithographically defined submicrometer channel length
Authors: Scheinert Susanne , Doll Theodor , Scherer Axel , Paasch Gernot , Hörselmann Ingo
Published: May 2004

We developed an underetching technique to define submicrometer channel length polymer field-effect transistors. Short-channel effects are avoided by using thin silicon dioxide as gate insulator. The transistors with 1 and 0.74 μm channel length operate at a voltage as low as 5 V with a low inverse subthreshold slope of 0.4–0.5 V/dec, on–off ratio of 104, and without short-channel effects. The poly(3-alcylthiophene)’s still suffer from a low mobility and hysteresis does occur, but it is negligible for the drain voltage variation. With our underetching technique also device structures with self-aligned buried gate and channel length below 0.4 μm are fabricated on polymer substrates.
Waveguide mode lasing via evanescent-wave-coupled gain from a thin cylindrical shell resonator
Authors: Moon Hee-Jong , Park Gun-Woo , Lee Sang-Bum , An Kyungwon , Lee Jai-Hyung
Published: May 2004

We reported waveguide mode lasing in a thin dielectric cylindrical shell made on the inner wall of a circular capillary, in which the laser oscillation was achieved through the evanescent-wave-coupled gain from the interior dye-doped liquid. Periodically peaked spectra of waveguide modes showed blueshift when the refractive index of interior liquid was decreased. We could quantitatively estimate the occupation factor of inner evanescent-wave portion from the dependence of blueshift, which allowed the spectral analysis on the effective cavity quality factor Q. Typical Q of the lasing waveguide modes was about 2×106.
Spin flop switching for magnetic random access memory
Authors: Worledge D. C.
Published: May 2004

By replacing the traditional single magnetic free layer in magnetic random access memory (MRAM) with a free layer composed of two antiferromagnetically coupled layers which switch by spin flop switching, the half select and activation energy problems that have hindered progress in MRAM to date can be essentially eliminated. By analytically and numerically solving a single domain model, the theory of spin flop switching for MRAM is developed here, including a discussion of the various types of easy axis hysteresis loops, the critical switching curve as a function of word and bit line fields, the role of thickness asymmetry, and the dependence of activation energy on applied field. The theory is developed for arbitrary thickness, length, width, magnetization, intrinsic anisotropy, and exchange coupling. Exact analytic formulas are given for the relevant switching fields and the activation energy. In particular, it is shown that the field required to switch the bit under half select can be many times larger than the field required for full select, and furthermore that the activation energy initially increases under application of a half select field.
One-dimensional nanostructures grown inside carbon nanotubes upon vapor deposition: A growth kinetic approach
Authors: Liu Qiu-Xiang , Wang Cheng-Xin , Yang Yu-Hua , Yang Guo-Wei
Published: May 2004

Aiming at controlling the growth of one-dimensional nanostructures inside carbon nanotubes, a growth kinetic approach was performed, with respect to the effect of nanosize induced additional pressure on growing kinetics, to theoretically elucidate the growth of one-dimensional nanostructures inside carbon nanotubes upon vapor deposition. Our analysis showed that the growth rate of one-dimensional nanostructures would go much higher once nuclei formed inside carbon nanotubes, due to the effect of surface tension induced by the nanosize curvature of carbon nanotubes. The results based on the proposed model are in good agreement with experimental data for nanowires grown inside carbon nanotubes upon vapor deposition.
Influence of toxic metals on activity of acid and alkaline phosphatase enzymes in metal-contaminated landfill soils
Authors: Roy S. , Bhattacharyya P. , Ghosh A. K.
Published: May 2004

A study was conducted to determine the effect of toxic metals on soil acid phosphatase (EC 3.1.3.2) and alkaline phosphatase (EC 3.1.3.1) enzyme activities in landfill soils. The enzyme activities were consistently higher in the landfill soils than in an uncontaminated alluvial soil. The landfill soils contained higher concentrations of metals (iron, manganese, cadmium, lead, zinc, copper) than did the alluvial soil. Enzyme activities were negatively correlated with the metals, with inhibition increasing with the bioavailability of the metals. It is suggested that the metals affected enzyme activities by behaving synergistically or additively with each other. Although the landfill soils had higher enzyme activities than the alluvial soil due to higher organic matter concentrations, the ratios of enzyme activity/organic carbon indicated that inhibition of enzyme synthesis and stability had occurred due to metal stress.
Programmable motion and patterning of molecules on solid surfaces
Authors: Suo Z. , Hong W.
Published: May 2004

Adsorbed on a solid surface, a molecule can migrate and carry an electric dipole moment. A nonuniform electric field can direct the motion of the molecule. A collection of the same molecules may aggregate into a monolayer island on the solid surface. Place such molecules on a dielectric substrate surface, beneath which an array of electrodes is buried. By varying the voltages of the electrodes individually, it is possible to program molecular patterning, direct an island to move in a desired trajectory, or merge several islands into a larger one. The dexterity may lead to new technologies, such as reconfigurable molecular patterning and programmable molecular cars. This paper develops a phase field model to simulate the molecular motion and patterning under the combined actions of dipole moments, intermolecular forces, entropy, and electrodes.
Anandamide transport is independent of fatty-acid amide hydrolase activity and is blocked by the hydrolysis-resistant inhibitor AM1172
Authors: Fegley D. , Kathuria S. , Mercier R. , Li C. , Goutopoulos A. , Makriyannis A. , Piomelli D.
Published: May 2004

The endogenous cannabinoid anandamide is removed from the synaptic space by a high-affinity transport system present in neurons and astrocytes, which is inhibited byN-(4-hydroxyphenyl)-arachidonamide (AM404). After internalization, anandamide is hydrolyzed by fatty-acid amide hydrolase (FAAH), an intracellular membrane-bound enzyme that also cleaves AM404. Based on kinetic evidence, it has recently been suggested that anandamide internalization may be mediated by passive diffusion driven by FAAH activity. To test this possibility, in the present study, we have investigated anandamide internalization in wild-type and FAAH-deficient (FAAH–/–) mice. Cortical neurons from either mouse strain internalized [3H]anandamide through a similar mechanism, i.e., via a rapid temperature-sensitive and saturable process, which was blocked by AM404. Moreover, systemic administration of AM404 to either wild-type or FAAH–/–mice enhanced the hypothermic effects of exogenous anandamide, a response that was prevented by the CB1cannabinoid antagonist rimonabant (SR141716A). The results indicate that anandamide internalization in mouse brain neurons is independent of FAAH activity. In further support of this conclusion, the compoundN-(5Z, 8Z, 11Z, 14Z eicosatetraenyl)-4-hydroxybenzamide (AM1172) blocked [3H]anandamide internalization in rodent cortical neurons and human astrocytoma cells without acting as a FAAH substrate or inhibitor. AM1172 may serve as a prototype for novel anandamide transport inhibitors with increased metabolic stability.
Hypoxia induces adhesion molecules on cancer cells: A missing link between Warburg effect and induction of selectin-ligand carbohydrates
Authors: Koike Tetsufumi , Kimura Naoko , Miyazaki Keiko , Yabuta Tomonori , Kumamoto Kensuke , Takenoshita Seiichi , Chen Jian , Kobayashi Masanobu , Hosokawa Masuo , Taniguchi Akiyoshi , Kojima Tetsuhito , Ishida Nobuhiro , Kawakita Masao , Yamamoto Harumi , Takematsu Hiromu , Suzuki Akemi , Kozutsumi Yasunori , Kanangi Reiji
Published: May 2004

Cancer cells undergo distinct metabolic changes to cope with their hypoxic environment. These changes are achieved at least partly by the action of transcriptional factors called hypoxia-inducible factors (HIFs). We investigated gene expression in cultured human colon cancer cells induced by hypoxic conditions with special reference to cell-adhesion molecules and carbohydrate determinants having cell-adhesive activity by using DNA-microarray and RT-PCR techniques. Hypoxic culture of colon cancer cells induced a marked increase in expression of selectin ligands, the sialyl Lewis x and sialyl Lewis a determinants at the cell surface, which led to a definite increase in cancer cell adhesion to endothelial E-selectin. The transcription of genes for fucosyltransferase VII (
FUT7
), sialyltransferase ST3Gal-I (
ST3O
), and UDP-galactose transporter-1 (
UGT1
), which are all known to be involved in the synthesis of the carbohydrate ligands for E-selectin, was significantly induced in cancer cells by hypoxic culture. In addition, a remarkable induction was detected in the genes for syndecan-4 (
SDC4
) and α5-integrin (
ITGA5
), the cell-adhesion molecules involved in the enhanced adhesion of cancer cells to fibronectin. The transcriptional induction by hypoxia was reproduced in the luciferase-reporter assays for these genes, which were significantly suppressed by the co-transfection of a dominant-negative form of HIF. These results indicate that the metabolic shifts of cancer cells partly mediated by HIFs significantly enhance their adhesion to vascular endothelial cells, through both selectin- and integrin-mediated pathways, and suggest that this enhancement further facilitates hematogenous metastasis of cancers and tumor angiogenesis.
Immune response in mice to ingested soya protein: antibody production, oral tolerance and maternal transfer
Authors: Christensen Hanne R. , Brix Susanne , Frøkiær Hanne
Published: May 2004

While allergic reactions to soya are increasingly investigated, the normal immune response to ingested soya is scarcely described. In the present study, we wanted to characterise the soya-specific immune response in healthy mice ingesting soya protein. Mice fed a soya-containing diet (F0) and mice of the first (F1) and second (F2) offspring generation bred on a soya protein-free diet were used either directly or were transferred between the soya-containing and soya protein-free diet during pregnancy or neonatal life. The mice were compared as to levels of naturally occurring specific antibodies analysed by ELISA, and to the presence of oral tolerance detected as a suppressed antibody and cell-proliferation response upon immunisation with soya protein. F0 mice generated soya-specific antibodies, while oral tolerance to the same soya proteins was also clearly induced. When F0 dams were transferred to soya protein-free feed before mating, the F1 and F2 offspring generations showed no significantly different response, indicating that soya-specific immune components were not maternally transmitted. However, the ingestion of dietary soya protein by F1 mice during late pregnancy and lactation caused a lasting antibody response in the offspring, but in this case in the absence of oral tolerance. This indicates that, under certain conditions, factors involved in spontaneous antibody production can be transmitted from mother to offspring. Understanding the immune response to soya protein ingested under healthy conditions is important in the assessment of adverse effects of soya protein and in the use of animal allergy models. The present results add to this understanding.
Effects of esculin and esculetin on the survival ofEscherichia coliO157 in human faecal slurries, continuous-flow simulations of the rumen and colon and in calves
Authors: Duncan Sylvia H. , McWilliam Leitch E. Carol , Stanley Karen N. , Richardson Anthony J. , Laven Richard A. , Flint Harry J. , Stewart Colin S.
Published: May 2004

The human pathogenEscherichia coliO157:H7 is thought to be spread by direct or indirect contact with infected animal or human faeces. The present study investigated the effects of the plant coumarin esculin and its aglycone esculetin on the survival of a strain ofE. coliO157 under gut conditions. The addition of these compounds to human faecal slurries andin vitrocontinuous-flow fermenter models simulating conditions in the human colon and rumen caused marked decreases in the survival of an introduced strain ofE. coliO157. When four calves were experimentally infected withE. coliO157 and fed esculin, the pathogen was detected in five of twenty-eight (18 %) of faecal samples examined post-inoculation, compared with thirteen of thirty-five (37 %) of faecal samples examined from five control calves not fed esculin. Coumarin compounds that occur naturally in dietary plants or when supplemented in the diet probably inhibit the survival ofE. coliO157 in the gut.
Psyllium and fat in diets differentially affect the activities and expressions of colonic sphingomyelinases and caspase in mice
Authors: Cheng Yajun , Ohlsson Lena , Duan Rui-Dong
Published: May 2004

Dietary fibre and fat affect colonic tumourigenesis and inflammation. Sphingomyelin metabolism may have implications for the pathogenesis of colonic tumours and ulcerative colitis. The present study examined the effects of psyllium and fat on the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. Mice were fed control, psyllium-containing (100 g/kg), high-fat (313 g/kg, 53 % energy as fat) or high-fat plus psyllium diets for 4 weeks. The activities of acid, neutral and alkaline sphingomyelinase (SMase), neutral ceramidase, and caspase 3, 8 and 9 in colonic mucosa were determined. The expressions of alkaline SMase and caspase 3 were examined. The psyllium-containing diet was found to increase significantly the activities of alkaline SMase and caspase 3 and decreased those of acid SMase and neutral ceramidase. The high-fat diet had opposite effects on these enzymes and attenuated the effects of psyllium. Western blotting showed that psyllium increased and high-fat decreased the levels of alkaline SMase and caspase 3 in colonic mucosa. The change in caspase 3 activity was positively correlated with that of alkaline SMase and negatively with acid SMase. No similar changes of acid and alkaline phosphatase activities in the colon or acid and neutral SMase activity in the liver were identified. In conclusion, colonic sphingomyelin metabolism and apoptosis were affected by psyllium and fat in an opposite manner. The results may have implications for colorectal tumourigenesis and inflammation.
Relationship between pre-pregnancy BMI and plasma zinc concentrations in early pregnancy
Authors: Tamura Tsunenobu , Goldenberg Robert L. , Johnston Kelley E. , Chapman Victoria R.
Published: May 2004

We previously reported that pregnant women whose plasma Zn concentrations were below the 50th percentile tended to have high pre-pregnancy BMI (kg/m2) values. We therefore hypothesized that in pregnant women, plasma Zn concentrations are negatively correlated with BMI. We evaluated the association between BMI values and plasma Zn concentrations in 1474 women whose blood samples were obtained before 15 weeks of gestation. Their mean age was 22·7 years and mean gestational age at blood sampling was 10 weeks. The mean plasma Zn concentration and BMI were 11·6 μmol/l and 26·6 kg/m2 respectively. Because plasma Zn concentrations decrease as gestational age increases, plasma Zn concentrations were standardized by Z-scores. Z-score distributions were compared among the quartiles of BMI. The highest BMI group had the lowest plasma Zn concentrations, whereas the lowest BMI group had the highest; the differences were significant between the BMI groups (P<0·0001). The interpretation of plasma Zn concentrations to assess Zn nutriture in pregnancy may be complicated not only by the well-established factor of gestational age at blood sampling, but also by a previously unrecognized factor, maternal BMI.
Selenium and iodine intakes and status in New Zealand and Australia
Authors: Thomson Christine D.
Published: May 2004

Most New Zealand soils contain relatively low concentrations of the anionic trace elements F, I and Se. Some areas of Australia also have a history of I deficiency. In view of current interest in establishing nutrient reference intakes for Se and I in New Zealand and Australia, it is timely to review current understanding of the intakes and status of these two elements. In spite of a recent increase in Se status, the status of New Zealanders remains low compared with populations of many other countries and may still be considered marginal, although the clinical consequences of the marginal Se status are unclear. There are no recent reports of blood Se levels in Australia, but earlier reports indicate that they were generally greater than those of New Zealanders. Similarly, the consequences of decreasing I status in Australia and New Zealand are unclear. Mild I deficiency in New Zealand has resulted in enlarged thyroid glands indicating an increased risk of goitre. Currently there is little evidence, however, of any associated clinical disease. Public health recommendations to reduce salt intake, together with the reduction in I content of dairy products, are likely to result in further decreases in the I status of New Zealand and Australian residents. Some action is needed to prevent this decline and it may be necessary to consider other means of fortification than iodized salt. The consequences of possible interactions between Se and I in human nutrition are also unclear and no practical recommendations can be made.
A CHEMICAL AND HISTOCHEMICAL STUDY OF THE LIPIDES OF THE PYLORIC CECUM OF THE STARFISH, ASTERIAS FORBESI
Authors: Karnovsky Manfred L. , Jeffrey Susan Skilling , Thompson Michaela Smits , Deane Helen Wendler
Published: May 2004

The lipides of the diverticula of Asterias forbesi have been studied by histochemical and biochemical means.

Correlations between results obtained by histochemical examination of sections, and chemical analysis of isolated lipide have been made, particularly with respect to phosphatides, steroids, and aldehyde lipides.

The results of the histochemical study were in good agreement with the chemical data as to the nature of the phosphatide fraction, the presence of acetone-soluble aldehyde lipides, and the composition of the free droplet fat.

Homogenized diverticula were differentially centrifuged in order to establish the distribution of types of lipides in the various cellular components.

In addition, data have been presented which demonstrate a direct correlation between the titer of α-glycerol ethers and that of acetone-soluble lipide acetals in the unsaponifiable fraction.
THE DISTRIBUTION OF HISTOCHEMICALLY DEMONSTRABLE SUCCINIC DEHYDROGENASE AND OF MITOCHONDRIA IN TONGUE AND SKELETAL MUSCLES
Authors: Wachstein M. , Meisel E.
Published: May 2004

Various skeletal muscles show considerable variations in histochemically demonstrable succinic dehydrogenase activity. In muscles from the lower extremities, the back, and the abdominal wall, only some fibers reveal evidence of enzymatic staining. In the diaphragm and masseter more fibers react positively. In the tongue, however, all fibers show marked activity comparable to that found regularly in the heart. There is a close similarity in the distribution of histochemically demonstrable succinic dehydrogenase and stainable mitochondria in tissue sections.
EVIDENCE OF DIFFERENCES IN THE DESOXYRIBONUCLEOPROTEIN COMPLEX OF RAPIDLY PROLIFERATING AND NON-DIVIDING CELLS
Authors: Bloch David P. , Godman Gabriel C.
Published: May 2004

1. Quantitative cytophotometric analysis of the interphase cells of a rapidly proliferating differentiated tissue such as liver of new born rat, indicates that these cells can be separated into two groups on the basis of their staining characteristics after methanol fixation.

2. These groups are thought to correspond to two stages of interphase. The first, called "autosynthetic interphase," comprises cells which are duplicating chromosomal material in preparation for mitosis, and shows parallel increases in the methyl green and Feulgen staining of DNA and the fast green staining of histone from the diploid (2 C) to double these values (4 C).

3. The second group is designated the "heterosynthetic interphase," during which the cell ceases proliferating and functions in a manner commensurate with its state of differentiation. In this stage Feulgen staining indicates the diploid chromosomal complement, but there is a decreased capacity of the DNA to bind methyl green and of the histone to bind fast green.

4. The difference between the methyl green binding of the heterosynthetic and autosynthetic 2 C cells is due to the presence of a protein in the former which presumably inhibits staining by competing with the dye for binding sites on the DNA. The effect of this inhibition can be removed by extracting the protein, or by blocking the protein basic groups.

5. The decreased fast green staining of histone in the heterosynthetic cells can be minimized by prolonged fixation with formaldehyde. It is thought to stem either from a similar type of inhibition, or from an increased susceptibility of the histone to loss from the cell during this stage.

6. While histone inhibits methyl green staining of DNA in all cells, the differences between the staining properties of the autosynthetic and heterosynthetic interphase cells are believed to be due to another protein, whose properties appear similar to those of the chromosomal "residual protein." It is concluded that a complex of DNA and residual protein existing during the heterosynthetic interphase is dissociated during the autosynthetic interphase.
ULTRASTRUCTURE OF THE LAMELLAE AND GRANA IN THE CHLOROPLASTS OF ZEA MAYS L
Authors: Hodge A. J. , McLean J. D. , Mercer F. V.
Published: May 2004

The fine structure of the chloroplasts of maize (Zea mays L.) has been investigated by electron microscopic examination of ultrathin sections of leaves fixed in buffered osmium tetroxide solutions. Both the parenchyma sheath and mesophyll chloroplasts contain a system of densely staining lamellae about 125 A thick immersed in a finely granular matrix material (the stroma), and are bounded by a thin limiting membrane which often appears as a double structure.

In the parenchyma sheath chloroplasts, the lamellae usually extend the full width of the disc-shaped plastids, and grana are absent. The mesophyll chloroplasts, however, contain numerous grana of a fairly regular cylindrical form. These consist of highly ordered stacks of dense lamellae, the interlamellar spacing being ca. 125 A. The grana are interlinked by a system of lamellae (intergrana lamellae) which are on the average about one-half as numerous as the lamellae within the grana. In general, this appears to be due to a bifurcation of the lamellae at the periphery of the granum, but more complex interrelationships have been observed.

The lamellae of the parenchyma sheath chloroplasts and those of both the grana and intergrana regions of the mesophyll chloroplasts exhibit a compound structure when oriented normally to the plane of the section. A central exceptionally dense line (ca. 35 A thick) designated the P zone is interposed between two less dense layers (the L zones, ca. 45 A thick), the outer borders of which are defined by thin dense lines (the C zones). Within the grana, the C zones, by virtue of their close apposition, give rise to thin dense intermediate lines (I zones) situated midway between adjacent P zones. A model of the lamellar structure is proposed in which mixed lipide layers (L zones) are linked to a protein layer (P zone) by non-polar interaction. Chlorophyll is distributed over the entire lamellar surface and held in the structure by van der Waals interaction of the phytol "tail" with the hydrocarbon moieties of the mixed lipide layers. The evidence in favour of the model is briefly discussed.
MICROTUBULATION OF THE INNER MEMBRANE OF THE NUCLEAR ENVELOPE
Authors: Meek G. A. , Moses M. J.
Published: May 2004

In the course of a light and electron microscopy study of spermatogenesis in the European crayfish, Astacus fluviatilis, spermatocytes of abnormal appearance were observed in two instances in individuals that had passed the mating period. The electron microscope showed that the inner membrane of the nuclear envelope of these cells was erupting into a mass of microtubules, 15 to 18 mµ in diameter and 0.5 µ or more in length, while the outer membrane transformed into cytoplasmic vesicles. Stages in the formation of these novel processes were followed. The plasma membrane of the affected cells was seen in some cases to erupt into similar although shorter microtubules. It is concluded that the phenomenon is part of a degenerative process in which the spermatocytes are being absorbed by sustentacular cells. It is suggested that the observations provide further evidence for a fundamental functional as well as a morphological similarity between the membranes bounding the nucleus and the plasma membrane.
ELECTRON MICROSCOPY OF THE OXYNTIC CELL IN THE GASTRIC GLANDS OF THE BULLFROG, RANA CATESBIANA
Authors: Sedar Albert W.
Published: May 2004

The oxyntic cell in the gastric glands of the bullfrog was examined in lead hydroxide-stained sections of gastric mucosae fixed in buffered osmium tetroxide and embedded in n-butyl methacrylate. During gastric acid secretion (pH 1–2) induced by histamine administration in cannulated frogs, the pattern of fine structure in the oxyntic cell differs strikingly from that in the oxyntic cell of the non-acid-secreting stomach. The relative number of smooth surfaced profiles decreases and a greater concentration of these elements is associated with the apical region of the oxyntic cell facing the lumen of the gastric gland. Similar concentrations of these elements are found in those regions of cytoplasm surrounding intercellular canaliculi which lie between adjacent cells and communicate with the lumen of a gastric gland. In these regions, the smooth surfaced profiles (35 to 65 mµ in width) characteristically form a tubular network. The membrane-bounded contents appear to be continuous with the extracellular medium, both on the capillary side and at the apical surface of the cell adjoining the lumen of the gastric gland. Mitochondria are distributed randomly in the cytoplasmic matrix of the oxyntic cell.
EFFECTS OF IN VIVO DECALCIFICATION ON ULTRASTRUCTURE OF ADULT RAT LIVER
Authors: Leeson T. S. , Kalant H.
Published: May 2004

A method of in situ perfusion of rat liver via the portal vein is described, by which osmiumtetroxide fixative can be introduced rapidly and uniformly to all parts of the tissue. Previous perfusion with balanced physiological saline solution, under the conditions described, of itself causes minimal change in the liver cell and liver architecture. Perfusion with a chelating agent causes no further detectable alteration within the liver cell but results in separation of the cells, even to the extent of producing a free cell suspension. The separation of cells is not accompanied by any recognizable damage to the plasma membrane but there is a striking tendency to pseudopod formation on the newly exposed surface. These findings provide direct evidence to support the classical concept of the importance of calcium to the adhesiveness of the plasma membrane in the tissues of the adult rat.