bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Coherency Stress on Kinetic Demixing
Authors: Reinke Christian , Johnson William C.
Published: April 2005

The influence of coherency stress, arising from differences in the partial molar volumes of the cations or an imposed displacement boundary condition, on composition profiles during kinetic demixing in ternary oxides subjected to a gradient in oxygen chemical potential is investigated. Coherency stresses can either enhance or diminish the magnitude of the kinetic demixing and shifts in interfacial composition owing to coherency stress on the order of several atomic percent, measured with respect to the case where stress is neglected, can be expected. For (Co, Mg)O subjected to displacement boundary conditions, steady‐state and time‐dependent demixing profiles are calculated and compared with experimental measurements. Although the composition profiles in the demixed solids are modified because of coherency stress, the main features of kinetic demixing remain unchanged.
Effect of Variations in Stoichiometry on the Surface Structure of SrTiO3 (001)
Authors: Liang Yong , Bonnell Dawn
Published: April 2005

Variations in Stoichiometry of SrTiO3 (001) surfaces with high‐temperature exposure to reducing environments were quantified with Rutherford backscattering and Auger electron spectroscopies. In addition to the expected oxygen loss, cation‐cation ratios varied systematically. Specifically, the surface becomes Ti‐ and O‐deficient at all temperatures. The associated surface structures determined by scanning tunneling microscopy showed that the surface accommodates nonstoichiometry by adopting periodic structures of characteristic suboxides with the formula Srn+1TinO3n+1. The chemical and structural variations are discussed in terms of mass transport models for sublimation and segregation. Since previous surface studies had been concerned with effects of sputtering or the behavior of stoichiometric surfaces, the results presented here represent the first systematic study of compositional variations upon annealing of the (001) surface.
Synthesis of a Mullite Precursor from Aluminum Nitrate and Tetraethoxysilane via Aqueous Homogeneous Precipitation: An 27Al and 29Si Liquid‐ and Solid‐State NMR Spectroscopic Study
Authors: Jaymes Isabelle , Douy André , Massiot Dominique , Busnel Jean‐Pierre
Published: April 2005

A simple aqueous process is described for the preparation of aluminosilicate colloids and chemically homogeneous mullite precursor gel. Starting from a solution of aluminum nitrate and silicic acid, aluminum is slowly hydrolyzed at 80–100°C by in situ generation of ammonia. A silica gel is rapidly made, probably by a catalytic effect of urea, the base generator. This gel is then slowly digested by partially hydrolyzed aluminum species which break the Si‐O‐Si bonds and link to the gel by Si‐O‐Al bonds. Progressively a clear colloidal sol is obtained and the colloidal particle size continues to decrease toward aluminosilicate species where the silicon atoms are in a single environment and may be linked to three hexacoordinated aluminum atoms and a hydroxyl group, by reference to natural imogolite. When the hydrolysis of aluminum is nearly complete, these particles are cross‐linked and a final gel precursor of mullite is obtained. This gel is chemically very homogeneous and crystallizes to mullite at 980°C. The structural evolution, from the first gel to the ceramic, has been followed by 27Al and 29Si liquid‐ and solid‐state MAS NMR spectroscopy.
Thermodynamic Assessment of the Ca‐Cu‐O System
Authors: Risold Daniel , Hallstedt Bengt , Gauckler Ludwig J.
Published: April 2005

The experimental data on the Ca‐Cu‐O system at 1 bar total pressure have been reviewed and an optimized thermodynamic description based on previous assessments of the binary systems is presented. Three ternary oxides are found which do not show significant solid solution and have been treated as stoichiometric compounds. The liquid exhibits a miscibility gap as in the Cu‐O binary. Only the copper oxide liquid extends into the ternary field and has been modeled with ternary parameters. A continuous thermodynamic description of the liquid phase from the metal to the oxide part has been obtained using the two‐sublattice ionic liquid model. The set of optimized parameters leads to a consistent and accurate thermodynamic description of the Ca‐Cu‐O system at 1 bar total pressure. Calculated CaO‐CuOx phase diagrams in air and 1.01 bar of O2, an oxygen potential diagram, an isothermal section at 1573 K, and various thermodynamic properties are shown and compared with experimental data. In particular the relative amounts of Cu+ and Cu2+ in the oxide liquid have been calculated in air and 1.01 bar of O2.
Preparation of Monodisperse and Spherical Zirconia Powders by Heating of Alcohol–Aqueous Salt Solutions
Authors: Moon Young Tae , Park Hong Kyu , Kim Do Kyung , Kim Chong Hee , Seog In‐Sig
Published: April 2005

A novel method is demonstrated which yields a spherical ZrO2 powder of narrow size distribution through heating of a zirconyl chloride solution with an alcohol–water mixture as the solvent. The kind and composition of the solvent mixture greatly influenced the behavior of the precipitation and the morphology of the resulting particles. When 1‐propanol or 2‐propanol was employed as the alcohol of the solvent mixture, the resulting particles had a spherical shape and a narrow size distribution. The particle size and the particle agglomeration level could be controlled by the amount of hydroxypropyl cellulose (HPC) in the solution. As‐prepared amorphous powder was crystallized to a mixture of metastable tetragonal phase and monoclinic phase at about 460°C. The metastable tetragonal phase was converted to the monoclinic phase as the calcination temperature was increased. After calcination, the spherical shape of the zirconia powder was retained, while its particle size was decreased slightly.
Molten‐Salt Synthesis of Ba1–xPbxTiO3 in the System BaTiO3–PbCl2
Authors: Ito Yoshiho , Shimada Shiro , Inagaki Michio
Published: April 2005

Ba1–xPbxTiO3 powder with a fixed composition was prepared by the reaction of BaTiO3 powders with molten PbCl2at various PbCl2/BaTiO3 molar ratios at 600° and 800°C in a nitrogen atmosphere. When 0.1 μm powder was used, the reaction was finished when x= 0.9. Two phases of BaTiO3and a solid solution of Ba1–xPbxTiO3 coexisted, but the final phase gave a solid solution of Ba1–xPbxTiO3 at 800°C. When 0.5 μm powder was used, the two phases coexisted in the products at 600°C at PbCl2/BaTiO3= 1.0. A sintered compact of Ba1–xPbxTiO3 powders solid solution was prepared by hot isostatic pressing, and its dielectric constant was measured in the temperature range 20°–550°C.
Size Sensitivity to Thermal Shock of Plasma‐Sprayed Ceramics and Factors Affecting the Size Effect
Authors: Lutz Ekkehard H.
Published: April 2005

The influence of specimen size on thermal shock resistance is investigated for relatively large plasma‐sprayed alumina tubes of varying diameter, length, and wall thickness. The observations suggest that an increasing wall thickness has a significant effect on the critical temperature difference for the onset of fracture, ΔTC, compared to the relatively weak effect of tube diameter and length. A plot of ΔTC versus the ratio of surface area and volume of the quenched specimens enables one to predict the respective value for larger tubes. The various parameters influencing the thermal shock size effect are addressed. According to the well‐known thermal stress equations, all measures to increase ΔTc, such as higher strength, lower Young's modulus, higher thermal conductivity, lower thermal expansion, and even less severe heat transfer conditions, simultaneously lead to an enhanced sensitivity of a ceramic component with respect to its size. For water quench tests, this effect may be intensified by a steep decrease of the surface heat conductance with temperature for ΔT > 400°C, resulting in a pronounced size sensitivity to thermal shock, particularly for ceramics of excellent thermal shock resistance.
Relationships between Hysteresis Measurements and the Constituent Properties of Ceramic Matrix Composites: II, Experimental Studies on Unidirectional Materials
Authors: Domergue Jean‐Marc , Vagaggini Emmanuel , Evans Anthony G.
Published: April 2005

The use of hysteresis loop measurements for assessing the constituent properties of unidirectional CMCs is evaluated, using basic theory described in a companion paper. Results are obtained on SiC/CAS and SiC/SiC composites. These materials exhibit very different hysteresis characteristics, reflected in differences in sliding stress, τ, and debond energy, Ti. These interface properties are manifest in the respective tensile stress/strain curves.
Microstructure, Flaw Tolerance, and Reliability of Ce‐TZP and Y‐TZP Ceramics
Authors: Readey Michael J. , McCallen Celeste L.
Published: April 2005

Ce‐TZP and Y‐TZP ceramics were heat‐treated for various times and temperatures in order to vary the microstructure. Flaw tolerance was investigated using the indentation–strength test. Reliability was quantified using conventional two‐parameter Weibull statistics. Some Ce‐TZP specimens were indented at slightly elevated temperatures where no transformation was observed. Results indicated that the Ce‐TZP specimens were extremely flaw tolerant, and showed a relatively high Weibull modulus that scaled with both R‐curve behavior and flaw tolerance. Y‐TZP, on the other hand, with very little if any R‐curve behavior or flaw tolerance, had a low Weibull modulus. The results also show that flaw history, i.e., whether or not a transformation zone exists along the wake of the crack, has a significant influence on strength. Strength was much less dependent on initial crack size when the crack had an associated transformation zone, whereas strength was highly dependent on cracks typical of natural processing defects. It is argued that the improvement in reliability, flaw tolerance, and dependence on flaw history are all ramifications of pronounced R‐curve behavior.
Origin of Absorption Bands Observed in the Spectra of Silver Ion‐Exchanged Soda–Lime–Silica Glass
Authors: Ahmed A. A. , Allah E. W. Abd
Published: April 2005

The spectral absorption of Ag‐containing soda–lime–silica glasses, prepared by ion exchange under different conditions and subjected to different heat treatments, was measured in the UV and visible. Tentative Gaussian resolution analysis was performed to accurately define the component bands of the experimentally observed absorption spectra. The spectral data were used to identify the different states of silver and the shape and the spatial arrangement of the silver particles formed in the samples treated under different conditions. The data obtained were also compared with the known characteristic absorption of definite silver states. The spectra of glasses after ion exchange showed a single sharp symmetrical absorption band in the UV at 305 nm. After heat treatment, one or two additional absorption bands in the UV and visible were observed, depending on the heat‐treatment conditions. The behavior of these bands—sequence of appearance, ranges of stability and intensity fluctuation, as a function of temperature and time of ion exchange and heat treatment—would suggest the following band assignment:

Band at 305 nm is associated with Ag+ ions.

Band at 350 nm is associated with Ag° (elemental Ag atoms).

Band at 420 nm is associated with (Ag°)n (silver crystallites, n is the number of silver atoms forming the crystallite).

This band assignment is in conformity with the sequence of events widely accepted to take place during silver staining. Additional information deduced from the single absorption band associated with silver particles indicates that the silver particles are spherical in shape and isolated from each other to the extent necessary to prevent electromagnetic interaction.
Crack‐tip Degradation Processes Observed during in situ Cyclic Fatigue of Partially Stabilized Zirconia
Authors: Hoffman Mark , Mai Yiu‐Wing , Wakayama Shuichi , Kawahara Masanori , Kishi Teruo
Published: April 2005

It is proposed that reduced transformation zone widths in Mg‐PSZ in cyclically versus critically propagated cracks are due to reductions in the crack‐tip toughness, consistent with an intrinsic cyclic fatigue mechanism. Cyclic fatigue crack growth in Mg‐PSZ was observed in situ in a SEM. Following cyclic fatigue, the samples were critically broken and the fracture surfaces observed. Extensive crack bridging by the precipitate phase was observed near the crack tip, and it is proposed that this crack bridging significantly affects the material's intrinsic toughness. Frictional degradation of the precipitate bridges occurs during cyclic loading and hence reduces the critical crack‐tip stress intensity factor for crack propagation. Reductions in the critical crack‐tip stress intensity factor also lead to reductions in the transformation zone widths during cyclic loading and hence the level of crack‐tip shielding caused by phase transformation. This appears to be the mechanism of cyclic fatigue. A degree of uncracked ligament bridging was also observed and is linked with the frequency of random large precipitates. However, analysis shows that its effect upon crack growth rates under cyclic load is limited.
Sellmeier Coefficients and Chromatic Dispersions for Some Tellurite Glasses
Authors: Ghosh Gorachand
Published: April 2005

Sellmeier coefficients are necessary to optimize the design parameters of optical devices. These coefficients are computed for binary tellurite glasses to find the chromatic dispersion behavior at any wavelength, particularly at the optical windows of optical fiber communication systems and femtosecond technology. A single‐oscillator DiDomenico and Wemple's dispersion equation is not sufficient to represent accurately the measured refractive indexes throughout the transmission range. As a minimum, a two‐pole Sellmeier equation is necessary to represent the data more accurately. Both the average electronic absorption band gap and the lattice absorption frequency, lying in the UV and IR region, respectively, affect the refractive indexes and their dispersion. Various other optical properties are discussed. A single‐oscillator dispersion equation is unable to verify the existence of zero‐dispersion wavelength.
22‐ene‐25‐oxa‐vitamin D: a new vitamin D analogue with profound immunosuppressive capacities
Authors: Daniel C. , Schlauch T. , Zügel U. , Steinmeyer A. , Radeke H. H. , Steinhilber D. , Stein J.
Published: April 2005

Background  The biologic role of 1,25‐dihydroxyvitamin D3, such as anti‐inflammatory functions, reduction of cytokine production by T cells and immunoglobulin production by B cells, is well established. However, its clinical use as an immunosuppressive agent is limited because of the hypercalcemic toxicity occurring after systemic application. The purpose of this study was to investigate the immunmodulatory effects of 22‐ene‐25‐oxa‐vitamin D (ZK156979), a novel low calcemic vitamin D analogue.

Materials and methods  Human peripheral blood mononuclear cells (PBMCs) from healthy donors were isolated using the Ficoll Hypaque technique, cultured for 24 h and treated with different concentrations of ZK156979 ranging from 10−5 to 10−10 mol L−1 compared with 1,25‐dihydroxyvitamin D3[10−5−10−10 mol L−1] following phytohaemagglutinin (PHA) stimulation. Interferon gamma (IFNγ), tumour necrosis factor alpha (TNFα), interleukin 1 beta (IL‐1β), interleukin 10 (IL‐10) and interleukin 4 (IL‐4) secretion in supernatants were measured by ELISA.

Results  ZK156979 inhibited the PHA‐induced Th1‐response (IFNγ and TNFα levels) and the macrophage‐product IL‐1β in a concentration‐dependent manner (10−10−10−5 mol L−1) with the efficiency on cytokine expression compared with 1,25‐dihydroxyvitamin D3 being slightly reduced. In contrast, ZK156979 and 1,25‐dihydroxyvitamin D3 both affected the Th2 response, leading to significantly increased IL‐10‐ and IL‐4 secretion.

Conclusions  ZK156979 is a member of novel vitamin D analogues revealing prominent immunomodulatory and suppressive characteristics with distinctive inhibition of Th1‐cytokines whereas the Th2 compartment is augmented, thus providing a considerable therapeutic potential in T‐cell ‐mediated diseases.
Oxidative stress and cardiovascular risk: the role of vascular NAD(P)H oxidase and its genetic variants
Authors: Soccio M. , Toniato E. , Evangelista V. , Carluccio M. , De Caterina R.
Published: April 2005

Several risk factors for coronary artery disease (CAD) induce atherosclerosis through endothelial activation and dysfunction, and ample evidence now suggests that the balance between production and removal of reactive oxygen species (ROS) – a condition termed oxidative stress – is implicated in such processes. A main source of ROS in vascular cells is the reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase system. This is a membrane‐associated enzyme, composed of five subunits, catalyzing the one‐electron reduction of oxygen, using NADH or NADPH as the electron donor. One of the system subunits, termed p22‐phox, has a polymorphic site on exon 4, associated with variable enzyme activity. This polymorphism is generated by a point mutation (C242T) producing a substitution of histidine with tyrosine at position 72, which affects one of the heme binding sites essential for the NAD(P)H enzyme activity. The consequent decrease of superoxide production thus characterizes a phenotype candidate for conferring to the carrier a reduced susceptibility to CAD. At present, however, the body of evidence from current literature is not yet sufficient to confirm or exclude the hypothesis that the C242T polymorphism protects from CAD. The functional effects of this polymorphism and the potential and its pathophysiological consequences also need further investigation.
Long‐term response and recovery to nutrient addition of a partitioned arctic lake
Authors: O'BRIEN W. JOHN , BARFIELD MICHAEL , BETTEZ NEIL , HERSHEY ANNE E. , HOBBIE JOHN E. , KIPPHUT GEORGE , KLING GEORGE , MILLER MICHAEL C.
Published: April 2005

1. To study the bottom‐up linkages in arctic lakes, we treated one side of a partitioned lake with inorganic nitrogen and phosphorus for a 6‐week period each summer for 6 years starting in the summer of 1985. We took a variety of weekly measurements to determine the impact of the nutrient loading on the lake and continued weekly measurements for 2–6 years after the cessation of nutrient loading to observe the recovery of the treated side. The loading rates (2.91 mmol N m−2 day−1 and 0.23 mmol P m−2 day−1) were five times the calculated loading rates for Toolik Lake, located nearby.

2. In all 6 years of nutrient addition, phytoplankton biomass and productivity were greater in the treated sector than the reference sector. In the first 4 years of nutrient addition there was no flux of phosphorus from the mineral‐rich sediments. This changed in the last 2 years of nutrient addition as phosphorus was released to the lake.

3. The response of the animal community to increased plant production was mixed. One of the four macro‐zooplankton species (Daphnia longiremis) increased in number by about twofold in the first 5 years. However, the copepod Cyclops scutifer showed no response during the treatment phase of the study. The benthic invertebrate response was also mixed. After a 2‐year lag time the snail Lymnaea elodes increased in the treated lake sector but chironomids did not.

4. Ecosystem response to fertilisation was not controlled solely by nutrient addition because phosphorus was not recycled from the sediments until the last 2 years of nutrient addition. Phytoplankton still showed the effects of nutrient addition in the recovery period and the hypolimnion of the treated sector was still anaerobic starting at 6 m in 1996.
Food webs in tropical Australian streams: shredders are not scarce
Authors: CHESHIRE KIM , BOYERO LUZ , PEARSON RICHARD G.
Published: April 2005

1. Macroinvertebrates were collected in dry and wet seasons from riffles and pools in two streams in tropical north Queensland. Total biomass, abundance and species richness were higher in riffles than in pools but did not differ between streams or seasons.

2. Gut contents of all species were identified. Cluster analysis based on gut contents identified five dietary groups: I, generalist collectors; II, generalist shredders and generalist predators; III, generalist scrapers; IV, specialist shredders; and V, specialist predators. Species were allocated to functional feeding groups (FFGs) based on these dietary groups.

3. Many species were generalist in their diets, but specialist predators and shredders were particularly prominent components of the invertebrate assemblages in terms of biomass and species richness.

4. Community composition (proportions of biomass, abundance and species richness of the different FFGs) varied between habitat types, but not between streams or seasons, although differences between riffles and pools varied with season.

5. Comparison of the fauna of 20 streams showed that our study sites were similar to, or not atypical of, low‐order streams in the Queensland wet tropics.
The impact of sediment reworking by opportunistic chironomids on specialised mayflies
Authors: DE HAAS ELSKE M. , KRAAK MICHIEL H.S. , KOELMANS ALBERT A. , ADMIRAAL WIM
Published: April 2005

1. Bioturbation, by definition, changes the structure and properties of sediments, thereby altering the environment of the bioturbator and other benthic species. In addition to the indirect effects of sediment reworking (e.g. changes in water quality), bioturbating species may also directly interfere with other species via competition. This study aims, therefore, to examine both the direct and indirect effects of sediment reworking by an opportunistic detritivore on survival and growth of a specialised mayfly species.

2. Bioturbation was imposed by adding different densities of the midge Chironomus riparius to clean and polluted sediments. Changes in water quality and sediment properties, and survival and growth of the mayfly Ephoron virgo were assessed.

3. Chironomid density had a strong negative effect on the concentrations of metals, nutrients and particles in the overlying water, but increased the penetration of oxygen into the sediment. Survival and growth of E. virgo were strongly reduced in the presence of chironomids. In the polluted sediment, the activity of chironomids enhanced the negative effects of pollution on E. virgo. In the clean sediment, inhibition of the mayfly was even more pronounced.

4. This suggests that direct disturbance by C. riparius was more important than indirect changes in water quality, and over‐ruled the potential positive effects of improved oxygen penetration. The results indicated that the distribution of small insects, such as E. virgo, can be limited by bioturbating benthic invertebrates.
Submerged macrophytes, zooplankton and the predominance of low‐ over high‐chlorophyll states in western boreal, shallow‐water wetlands
Authors: NORLIN J. IVOR , BAYLEY SUZANNE E. , ROSS LISETTE C. M.
Published: April 2005

1. Shallow‐water (<2 m deep) wetlands in northern Alberta's western boreal forest tend to have either extremely high‐chlorophyll, pea‐green water or water that is low in chlorophyll and clear. The relative importance of top‐down processes (e.g. zooplankton grazing) compared with bottom‐up processes (e.g. nutrient limitation) for regulating the existence of these alternate states has yet to be explicitly investigated in these poorly studied waterbodies.

2. To assess the relationship between chemical and biological factors and the predominance of low‐chlorophyll over high‐chlorophyll states, a survey of 24 shallow‐water wetlands in northern Alberta was conducted over the summers of 2001 and 2002.

3. In wetlands without fish, statistical analysis indicated that high‐ and low‐chlorophyll sites could be differentiated with 82% accuracy based solely on whether submerged aquatic vegetation (SAV) coverage was greater or less than 25%. Further, high‐SAV lakes with zooplankton communities dominated by large cladocerans were clear 96% of the time.

4. In the few wetlands that supported stickleback populations, large cladocerans were absent. However, the development of zooplankton communities dominated by small cladocera (Bosmina) with calanoid copepods in fish‐containing wetlands corresponded with a shift from high‐ to low‐chlorophyll states.

5. Results suggest that in fishless wetlands high‐SAV coverage and grazing by large, SAV‐associated cladocerans promotes low‐chlorophyll states. Results also suggest that suppression of macroinvertebrate predators by sticklebacks allowing Bosmina to flourish may also promote low‐chlorophyll, clear‐water conditions.
Benthic–pelagic coupling in the population dynamics of the harmful cyanobacterium Microcystis
Authors: VERSPAGEN JOLANDA M. H. , SNELDER EVELINE O. F. M. , VISSER PETRA M. , JÖHNK KLAUS D. , IBELINGS BAS W. , MUR LUUC R. , HUISMAN JEF
Published: April 2005

1. In eutrophic lakes, large amounts of the cyanobacterium Microcystis may overwinter in the sediment and re‐inoculate the water column in spring.

2. We monitored changes in pelagic and benthic populations of Microcystis in Lake Volkerak, The Netherlands. In addition, sedimentation rates and the rate of recruitment from the sediment were measured using traps. These data were used to model the coupling between the benthic and pelagic populations and to calculate the contribution of overwintering benthic and pelagic populations to the magnitude of the pelagic summer bloom.

3. Changes in the benthic Microcystis population showed a time lag of 3–14 weeks compared with the pelagic population. This time lag increased with lake depth. The largest amount of benthic Microcystis was found in the deepest parts of the lake. These observations suggest horizontal transport of sedimented Microcystis from shallow to deep parts of the lake.

4. Recruitment from and sedimentation to the sediment occurred throughout the year, with highest recruitment and sedimentation rates during summer. Model simulations indicate that the absence of benthic recruitment would reduce the summer bloom by 50%.

5. In spring, the total pelagic population was three to six times smaller than the total benthic population. Yet, model simulations predict that the absence of this small overwintering pelagic population would reduce the summer bloom by more than 64%.

6. Reduction of the overwintering pelagic populations, for instance by flushing, may be a useful management strategy to suppress or at least delay summer blooms of Microcystis.
Molecular cloning, characterization, and downregulation of an acyltransferase that catalyzes the malonylation of flavonoid and naphthol glucosides in tobacco cells
Authors: Taguchi Goro , Shitchi Yoshihiro , Shirasawa Sakiko , Yamamoto Hirobumi , Hayashida Nobuaki
Published: April 2005

Tobacco cells (Nicotiana tabacum L. Bright Yellow T‐13) exposed to harmful naphthols accumulate them as glucosylated and further modified compounds [Taguchi et al. (2003a) Plant Sci. 164, 231–240]. In this study, we identified the accumulated compounds to be 6′‐O‐malonylated glucosides of naphthols. Cells treated with various phenolic compounds accumulated the flavonoids mainly as malonylglucosides. To clarify the function of this malonylation in tobacco, we isolated the cDNA encoding a malonyltransferase (NtMaT1) from a cDNA library derived from tobacco cells. The heterologous expression of the gene in Escherichia coli revealed that the recombinant enzyme had malonyltransferase activity against several phenolic glucosides such as flavonoid 7‐O‐glucosides, flavonoid 3‐O‐glucosides and naphthol glucosides. The substrate preference of the enzyme was similar to that of the tobacco cell extract. Malonylation activity in the transgenic cells markedly decreased with the suppression of the expression of NtMaT1 mRNA in tobacco BY‐2 cells by RNA interference. The compounds administered to the transgenic cells were accumulated in the cells as glucosides or other modified compounds in place of malonylglucosides. These results show that NtMaT1 is the main catalyst of malonylation on glucosides of xenobiotic flavonoids and naphthols in tobacco plants.
Kinase partner protein interacts with the LePRK1 and LePRK2 receptor kinases and plays a role in polarized pollen tube growth
Authors: Kaothien Pulla , Ok Sung Han , Shuai Bin , Wengier Diego , Cotter Robyn , Kelley Dior , Kiriakopolos Stephanie , Muschietti Jorge , McCormick Sheila
Published: April 2005

The pollen‐specific receptor kinases LePRK1 and LePRK2 have localization and expression profiles that strongly suggest they play roles in pollen germination and tube growth. To identify downstream components of LePRK signaling, we used their cytoplasmic domains (CDs) as baits in yeast two‐hybrid screens of a tomato pollen cDNA library. A pollen‐specific protein we named kinase partner protein (KPP) interacted with the CDs of both LePRK1 and LePRK2 in yeast and in an in vitro pull‐down assay, and with LePRK2 in a co‐immunoprecipitation assay. KPP is a peripheral membrane protein and is phosphorylated in pollen. Pollen tubes over‐expressing KPP developed balloon‐like tips with abnormal cytoplasmic streaming and F‐actin arrangements and plants over‐expressing KPP exhibited impaired transmission of the transgene through the male. KPP‐like genes are found only in plants; the 14 family members in Arabidopsis thaliana exhibit diverse expression patterns and potentially play roles in signaling pathways in other tissues.
The Calvin cycle in cyanobacteria is regulated by CP12 via the NAD(H)/NADP(H) ratio under light/dark conditions
Authors: Tamoi Masahiro , Miyazaki Takashi , Fukamizo Tamo , Shigeoka Shigeru
Published: April 2005

In Synechococcus PCC7942 cells grown in the dark, the concentrations of NAD(H) and NADP(H) were 128 ± 2.5 and 483 ± 4.0 μm, respectively, while those in the cells under light conditions were 100 ± 5.0 and 649 ± 7.0 μm, respectively. Analysis of gel filtration indicated that the change of the ratio of NADP(H) to NAD(H) in cyanobacterial cells under light/dark conditions controls the reversible dissociation of the PRK/CP12/GAPDH complex (approximately 520 kDa) consisting of phosphoribulokinase (PRK), CP12, and glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH). S. 7942 CP12 lacked the two Cys residues essential for formation of the N‐terminal peptide loop in the CP12 of higher plants, but the N‐terminal region of S. 7942 CP12 had the ability to be associated with PRK. The growth of mutant cells in which the CP12 gene was disrupted by a kanamycin resistance cartridge gene was almost the same as that of wild‐type cells under continuous light conditions. However, under the light/dark cycle (12 h/12 h), the growth of CP12‐disrupted mutant cells was significantly inhibited compared with that of wild‐type cells. The mutant cells showed a decreased rate of O2 consumption and an increased level of ribulose 1,5‐bisphosphate compared with wild‐type cells in the dark. These data suggest that under light and dark conditions, the oligomerization of CP12 with PRK and GAPDH regulates the activities of both enzymes and thus the carbon flow from the Calvin cycle to the oxidative pentose phosphate cycle.
AtATG18a is required for the formation of autophagosomes during nutrient stress and senescence in Arabidopsis thaliana
Authors: Xiong Yan , Contento Anthony L. , Bassham Diane C.
Published: April 2005

Vacuolar autophagy is a major pathway by which eukaryotic cells degrade macromolecules, either to remove damaged or unnecessary proteins, or to produce respiratory substrates and raw materials to survive periods of nutrient deficiency. During autophagy, a double membrane forms around cytoplasmic components to generate an autophagosome, which is transported to the vacuole. The outer membrane fuses with the vacuole or lysosome, and the inner membrane and its contents are degraded by vacuolar or lysosomal hydrolases. We have identified a small gene family in Arabidopsis thaliana, members of which show sequence similarity to the yeast autophagy gene ATG18. Members of the AtATG18 gene family are differentially expressed in response to different growth conditions, and one member of this family, AtATG18a, is induced both during sucrose and nitrogen starvation and during senescence. RNA interference was used to generate transgenic lines with reduced AtATG18a expression. These lines show hypersensitivity to sucrose and nitrogen starvation and premature senescence, both during natural senescence of leaves and in a detached leaf assay. Staining with the autophagosome‐specific fluorescent dye monodansylcadaverine revealed that, unlike wild‐type plants, AtATG18a RNA interference plants are unable to produce autophagosomes in response to starvation or senescence conditions. We conclude that the AtATG18a protein is likely to be required for autophagosome formation in Arabidopsis.
Evaluation of chloroquine (CQ) and sulphadoxine/pyrimethamine (SP) therapy in uncomplicated falciparum malaria in Indo‐Myanmar border areas
Authors: Mohapatra P. K. , Prakash Anil , Taison K. , Negmu K. , Gohain A. C. , Namchoom N. S. , Wange D. , Bhattacharyya D. R. , Goswami B. K. , Borgohain B. K. , Mahanta J.
Published: April 2005

Chloroquine (CQ) and sulphadoxine/pyrimethamine (SP) are two first‐line antimalarials used under the existing Indian National Drug Policy in the north‐eastern region of India bordering several countries including Myanmar. Although widespread resistance to antimalarials in Plasmodium falciparum has been reported from western Myanmar, information from the Indian side of the border is scarce. We studied the therapeutic response to CQ and SP at four sites in Changlang and Lohit, two administrative districts of Arunachal Pradesh bordering Myanmar. We monitored uncomplicated falciparum malaria patients after treatment with standard regimens of CQ and SP for 28 days following the revised in‐vivo protocol of the World Health Organization. A total of 236 patients, 95 in the CQ group and 141 in the SP group, participated. We recorded 23.8% early treatment failures to CQ and 14.1% to SP; late clinical failures of 14.3 and 12.6%; late parasitological failures of 10.7 and 8.1% and adequate clinical and parasitological responses of 51.2 and 65.2%, respectively. The significantly different treatment failure rates seen in Chowkham (furthest from Indo‐Myanmar border) and Jairampur/Nampong (nearest to Indo‐Myanmar border) for chloroquine (Cox proportion hazard ratio 9.1, P < 0.0001) and SP (Cox proportion hazard ratio 7.35, P = 0.001) denote a non‐response gradient to the two antimalarials extending from the international border. The gradient is probably indicative of the direction of movement of the drug‐resistant P. falciparum parasite. The utility of chloroquine as the first‐line drug under the present National Drug Policy in these areas needs reconsideration.
Endemic coastal malaria in the Thousand Islands District, near Jakarta, Indonesia
Authors: Maguire Jason D. , Tuti Sekar , Sismadi Priyanto , Wiady Iwa , Basri Hasan , Krisin  , Masbar Sofyan , Projodipuro Purnomo , Elyazar Iqbal R. F. , Corwin Andrew L. , Bangs Michael J.
Published: April 2005

Objectives  To conduct malaria surveillance near Jakarta where only imported malaria has been described over the past two decades and to characterize endemicity and risk to heavily populated peri‐urban locations.

Methods  Standard cross‐sectional malariometric surveys and mosquito collections at the Thousand Islands District and developing peri‐urban areas of Jakarta.

Results  During October 2000 outbreak investigations in the Tidung Island group, the slide positive rate was 47% (38%Plasmodium falciparum, 7%P. vivax, and 2% mixed infections) among 733 persons screened. Very few parasitemic inhabitants were symptomatic (<1%), and native residents were more commonly infected than immigrants (odds ratio 1.72), consistent with endemic autochthonous transmission. Adult and larval mosquito collections detected Anopheles sundaicus. In June 2001, prevalence of parasitemia at Pari Island, where sampling was adequate for comparison, remained high, 32%vs. 43% previously. Among 1377 individuals screened at nearby Tangerang District, a heavily populated mainland suburb dominated by fishponds through which many islanders travel to Jakarta, only 19 malaria infections were identified, all imported from Pari Island. Entomological surveillance in Tangerang identified An. subpictus, An. vagus, and An. barbirostris, all considered minor malaria vectors on Java.

Conclusions  Malaria is endemic in the Tidung Island group. Imported malaria occurs in the heavily populated Tangerang District where coastal development is increasing and vector breeding sites and demographic patterns lend increasingly to malaria importation and risk of emergent malaria. Careful attention to the impact of coastal development activities on vector populations and efforts to prevent introduction of An. sundaicus are warranted.
La difficulté du partenariat entre professionnels de santé et mutualistes: le cas de la mutuelle de santé Maliando en Guinée‐Conakry
Authors: Criel Bart , Diallo Alpha Ahmadou , Vennet Jean Van der , Waelkens Maria‐Pia , Wiegandt Axel
Published: April 2005

Une mutuelle communautaire d'aire de santé (MUCAS) a été conçue et mise en place en 1998 en Guinée forestière dans le cadre du projet de recherche action PRIMA (Projet de recherche sur le partage du risque maladie). Ce projet visait à tester sous quelles conditions un système mutualiste permet d'améliorer l'accès à des soins de qualité. La spécificité du modèle MUCAS est double: d'une part, le souhait de l'intégrer dans le système local de santé par la construction d'un partenariat entre mutuelle et services de santé; et d'autre part, l'effort systématique de l’équipe de recherche locale pour essayer d‘impliquer les professionnels de santé, aux niveaux opérationnels aussi bien que gestionnaires du système, dans la planification et la mise en place de la mutuelle. Nous présentons ici les résultats d'une étude de la perception du modèle MUCAS par les professionnels de santé guinéens. L’étude a consisté en une série d'interviews semi‐structurées faite auprès de 16 agents de santé au mois d'avril 2000. Les résultats montrent que les professionnels perçoivent la mutuelle comme une stratégie efficace pour améliorer l'accès aux soins, mais ils illustrent également le manque de compréhension, l'incertitude et même la résistance que le modèle semble avoir suscité auprès des professionnels. L'approche partenariale, si elle a été comprise, n'a pas été intériorisée par les professionnels de la santé. Ils maîtrisent l'outil technique mais sont désemparés dans leur dialogue avec la population. Cette étude illustre les difficultés d'un réel partenariat entre population et services de santé et le besoin de mieux préparer, former et encadrer les professionnels lors de la conception, la mise en place et l'organisation de modèles mutualistes de financement des soins de santé. L'importance de cet aspect a été insuffisamment reconnue par l’équipe de recherche malgré sa bonne volonté et les nombreux moments de concertation qu‘elle a organisé entre les différentes parties prenantes. Une leçon importante de cette expérience est le besoin pour les promoteurs de concevoir et d'opérer des systèmes mutualistes dans lesquels les attentes et craintes des agents de santé sont mieux identifiées et mieux prises en compte.
Range expansion by moose into coastal temperate rainforests of British Columbia, Canada
Authors: Darimont C. T. , Paquet P. C. , Reimchen T. E. , Crichton V.
Published: April 2005

Ranges of species are dynamic and respond to long‐term climate change and contemporary effects such as habitat modification. We report here that moose (Alces alces) have recently colonized coastal temperate rainforests of British Columbia, Canada. Contrary to recent publications, field observations of moose and their sign, combined with their occurrence in wolf (Canis lupus) faeces, suggest that moose are now widespread on the coastal mainland and occur on least three islands. Traditional ecological knowledge (information accumulated by aboriginal peoples about their environment) suggests that colonization occurred during the mid 1900s, concomitant with logging of major watersheds that bisect the Coast Mountain Range. Range expansion by moose may have ecological consequences such as alteration of predator–prey dynamics and transmission of disease to native deer (Odocoileus hemionus).
Genetic diversity does not affect the invasiveness of fountain grass (Pennisetum setaceum) in Arizona, California and Hawaii
Authors: Poulin Jessica , Weller Stephen G. , Sakai Ann K.
Published: April 2005

Pennisetum setaceum (Poaceae) is a perennial bunch grass that invaded the United States during the 20th century and is highly invasive in Hawaii, moderately invasive in Arizona, and not yet invasive in southern California. Pennisetum setaceum is apomictic, a condition that is normally associated with low genetic variation within populations, but even moderate levels of genetic variation among populations could account for differences in invasiveness. To determine whether genetic factors are causing the variable invasion success, we used Inter‐Simple Sequence Repeat markers (ISSRs) to examine genetic variation in populations from the three areas. Screening of 16 primers revealed no genetic variation within any population or between any geographical areas, a pattern consistent with complete apomixis. Variation in invasion success appears unrelated to genetic differences among populations. Differences in the seasonal timing of rainfall among the regions may be the cause of variable invasiveness of fountain grass. Alternatively, differences in timing of introduction or duration of lag phase may have limited invasiveness in Arizona and southern California.
The sensitivity of lizards to elevation: A case study from south‐eastern Australia
Authors: Fischer Joern , Lindenmayer David B.
Published: April 2005

Lizard distribution patterns were examined in relation to elevation in two undulating landscapes. We asked three specific questions: (1) Were different lizard species associated with particular elevations? (2) Did biological attributes of lizards (e.g. body size, colour, reproduction strategy, etc.) vary with elevation? (3) Did species richness of lizards vary with elevation? Field data were collected in two undulating production landscapes in south‐eastern Australia, approximately 100 km to the west of the Australian Capital Territory. Lizards were surveyed using 648 pitfall traps and 3840 m of drift fence. Both study landscapes were divided into 50 m elevation classes. For each elevation class, survey effort, the capture rate of individual species, and species richness were recorded. Correspondence analysis was used to sort lizards according to their altitudinal distribution profiles. Analysis of variance was used to examine if biological attributes of lizards were related to their altitudinal distribution profiles. Generalized linear modelling was used to relate elevation to the capture rate of individual species, and to species richness. Lizard species differed in their altitudinal preferences. Skinks, taxa with a Bassian distribution or distribution restricted to the Great Dividing Range, dark‐bodied species and viviparous species were more likely to inhabit high elevations. Elevation was significantly related to the capture rate of seven species, and ecologically similar species replaced one another as elevation increased. Species richness peaked significantly at intermediate elevations in both landscapes. We conclude that lizards were highly sensitive to elevation. Elevation changes of as little as 50 m may be related to a change in species richness or species composition. Future research should assess if reptiles in other undulating landscapes with a temperate climate are similarly sensitive to elevation. If so, conservation activities in these landscapes need to consider the full spectrum of topographic positions and elevations.
Minimum residence time, biogeographical origin, and life cycle as determinants of the geographical extent of naturalized plants in continental Chile
Authors: Castro Sergio A. , Figueroa Javier A. , Muñoz‐Schick Mélica , Jaksic Fabian M.
Published: April 2005

The geographical extent of exotic plant species is a major component of invasiveness, which has been explained by intrinsic attributes of the plants, such as growth rate, reproductive type, life form, and biogeographical origin. We assessed quantitatively life cycle and biogeographical origin as determinants of the geographical distribution of naturalized plants in continental Chile, using minimum residence time (MRT) as an estimator of introduction date. We assembled a database with information on 428 plants (principally herbs) in continental Chile, corresponding to 61% of the exotic naturalized flora. For each species we recorded: (1) minimum residence time (introduction date or first recorded date in the country); (2) biogeographical origin (American, Eurasian, others); (3) life cycle (annual, perennial, others); (4) number of Chilean regions occupied by the plant. We found that 82 species (19%) have been recorded in only one region of Chile, while only three species have been found in all 13 regions of the country. About 89% of the species (381) have been found only in central Chile (Regions IV to VIII), while the remaining 11% (47) are found only in the northern (Regions I to III) or southern parts of the country (Regions IX to XII). We detected significant differences in regional spread of naturalized plants according to minimum residence time: those species with shorter MRT had more limited spread ranges than those with longer MRT. Biogeographical origin and life cycle did not explain geographical extent in Chile. This study shows that historical factors are more important than biological ones in determining the geographical extent of naturalized plants in continental Chile. Thus, caution should be exercised when assigning value to biological attributes that may confer invasiveness to naturalized plants.
Genetic diversity and differentiation of two Mediterranean pines (Pinus halepensis Mill. and Pinus pinaster Ait.) along a latitudinal cline using chloroplast microsatellite markers
Authors: Gómez A. , Vendramin G. G. , González‐Martínez S. C. , Alía R.
Published: April 2005

Several studies have reported glacial refugia and migration pathways for different pine species in the Iberian Peninsula, all of them based on a single‐species approach. In this paper, chloroplast microsatellites (cpSSRs) are used to compare population genetic structure and diversity estimates for interspecific pairs of populations located along a cline from southwestern (latitude 36°32′ N, longitude 5°17′ W) to northeastern Spain (latitude 42°14′ N, longitude 2°47′ E) in two widely distributed Mediterranean pines, Pinus halepensis Mill. and Pinus pinaster Ait. Some cpSSRs were shared between species, facilitating comparison of levels of gene diversity at the species level and inferences about within and among species differentiation. P. pinaster showed a much higher number of variants (29) and haplotypes (69) than P. halepensis (20 and 21, respectively). Moreover, genetic diversity estimates for interspecific pairs of populations along the cline were negatively correlated. Three main causes may explain the differences between species in the present‐day distribution of genetic diversity: (1) the distribution of genetic variability before the Quaternary glaciations, with an earlier presence of P. pinaster in the Iberian Peninsula and a late spread of P. halepensis from eastern and central Europe, (2) the location of the Holocene glacial refugia and the migration pathways from these refugia to the present‐day range (from northeast to southwest in P. halepensis and from southwest to northeast and northwest in P. pinaster) and (3) the interactions between species during the postglacial spread.