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Pores
Kinds of Pores Terms modified by Pores Selected AbstractsFormation of the Fertilization Pore during Oogenesis of the Fern Ceratopteris thalictroidesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2010Jian-Guo Cao The development of the fertilization pore during oogenesis of the fern Ceratopteris thalictroides was followed using transmission electron microscopy. The newly formed egg is appressed closely to the adjacent cells. There are well-developed plasmodesmata between the egg and the ventral canal cell, but none between the egg and the jacket cells of the archegonium. During maturation, a separation cavity is formed around the egg. However, a pore region persistently connects the egg and the ventral canal cell. The extra egg membrane is formed by deposition of sheets of endoplasmic reticulum (ER), but no ER is deposited on the inner surface of the pore region. Thus, a fertilization pore, covered by a layer of plasmalemma, is formed. The ventral canal cell undoubtedly participates the formation of the fertilization pore, probably by absorbing the sheets of ER beneath the pore region. The functional significance of the ventral canal cell in formation of the fertilization pore is discussed. The features of the mature egg include that abundant concentric membranes and osmiophilic vesicles occur in the cytoplasm of the mature egg. The initial, round nucleus of the egg eventually becomes cup-shaped. This investigation gives some new insights about the cells participating oogenesis in ferns. [source] Influence of fibre length and filler particle size on pore structure and mechanical strength of filler-containing paperTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2000Noriyoshi Kinoshita Abstract Test sheets were prepared by incorporating softwood pulp with silica filler, PW-5 (diameter 4.5 ,m) or PW-20 (15 ,m). Length-weighted averages of fibre were 2.5 (uncut fibre) and 1.25 mm (short-cut fibre). Pore sizes less than 150 urn were measured by mercury porosimeter. Sheets of short-cut fibres and mixed with uncut fibres at ratio of 3:1 or 1:3 had larger pore volumes than others tested. When filler content increased, the total pore volume increased for PW-20 sheets, but it did not for PW-5 sheets with short-cut fibres. Tensile index and folding endurance were very much affected by fibre length. Contact number on a fibre was calculated by computer simulation, and it had a linear relation with tensile index of sheet. Des échantillons de feuilles ont été préparés en incorporant dans de la pâte de bois tendre une charge de silice, soit du PW-5 (diamètre 4,5 ,m) ou du PW-20 (15 ,n). Les moyennes pondérées de la longueur des fibres sont de 2,5 (fibre non coupée) et 1,25 mm (fibre courte). Des distributions de taille des pores inférieures à 150 ,m ont été mesurées à l'aide d'un porosimètre au mercure. Les feuilles fabriquées avec des fibres courtes et celles mélangées à des fibres non coupees dans des rapports de 3:1 et 1:3 présentent de plus grands volumes de pores que les autres. Lorsque la charge augmente, le volume total des pores augmente pour les feuilles ayant du PW-20, ce qui n'est pas le cas pour les feuilles contenant du PW-5 avec des fibres courtes. L'indice de traction et l'endurance au pliage sont très influencés par la longueur des fibres. Le nombre de contacts sur une fibre a été calculé au moyen de simulations par ordinateur et il varie linéairement avec l'indice de traction des feuilles. [source] Light-Induced Control of Protein Translocation by the SecYEG Complex,ANGEWANDTE CHEMIE, Issue 40 2010Francesco Bonardi Schließt die Pore! Ein organochemischer Photoschalter wurde in zwei transmembranäre Segmente eingeführt, die die laterale Öffnung der proteinleitenden Pore in Bakterienmembranen umschließen. Reversibles Schalten des Azobenzols zwischen der trans - und cis -Konfiguration durch Bestrahlung mit sichtbarem und UV-Licht erzwingt das Öffnen und Schließen der Pore (siehe Schema). [source] Study on Crack-like Pores of Al Foams Made via the Powder-Metallurgy Route,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Lei Wang Mechanisms for the formation and disappearance of the crack-like pores generated during the early stage of Al foaming are investigated. A model for their disappearance process is proposed for the first time. The stress, perpendicular to the compaction direction in uniaxial cold compaction, is caused by the interaction of the Al powder under a high compaction pressure and is the main reason for the formation of the crack-like pores. The results of the model analysis and theoretical calculations suggest that the pressure difference ,P between the initial, round bubbles and the crack-like pores is the driving force for their disappearance. The rapid reduction of ,P is attributed to the decomposition characteristics of the TiH2 powder. [source] Creating Aligned, Elongated Pores in Titanium Foams by Swaging of Preforms with Ductile Space-Holder,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Yasumasa Chino Preforms of titanium powders containing a naphthalene-based space-holder phase are swaged. The elongated space-holder particles are sublimated and the preform is sintered, resulting in titanium foams with 49,65% porosity consisting of: a) small equiaxed pores from incomplete powder sintering and b) larger, elongated pores replicating the space-holder, which are aligned along the swaging direction. The foam carbon content (0.39,wt%) is below the value for severe titanium embrittlement. [source] Improvement in the Specific Strength by Arranging Closed Pores in Fully Densified Zirconia Ceramics,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Akira Kishimoto Superplastic-foamed porous ceramics containing numerous closed pores were fabricated. The bending strength of the fabricated ceramics with the smallest pores was close to half that of fully dense ones, even with a porosity of 27%. The smaller pores were introduced selectively between top and bottom surfaces. The resultant dense/porous/dense layered ceramics had a specific mechanical strength greater than that of monolithic dense ceramics. [source] Molecular Recognition by Synthetic Multifunctional Pores in Practice: Are Structural Studies Really Helpful?,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2006Y. Baudry Abstract This account summarizes five years of research devoted to the development of the concept of synthetic multifunctional pores. The objective is to complement a comprehensive graphical summary of molecular recognition with a survey of structural studies on the same topic. The relevance of the latter for research focusing on creation and application of supramolecular functional materials is discussed briefly in a subjective manner. [source] Presence of pores and vacuoles in set endodontic sealersINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2005L. Mutal Abstract Aim, To assess qualitatively the presence of pores and vacuoles in the structure of various endodontic sealers when set. Methodology, Eight specimens were prepared in keeping with Instituto Argentino de Racionalización de Materiales (IRAM) and ISO regulations for each of the 10 sealers assessed. Four specimens per sealer were examined to identify the presence of structural defects, termed pores, on the external surface. The remaining four specimens were used to examine the presence of defects on the surface exposed by cross-sectional fracture; these were termed vacuoles. The largest and smallest diameters of the pores and vacuoles were measured by scanning electron microscope on both surfaces. The structural defects were classified according to their frequency as abundant, frequent, scarce or exceptional. Results, Pores and vacuoles were consistently found in every specimen of each sealer. However, their frequency and dimensions were greater in zinc-eugenol-based sealers than in epoxy-resins and glass,ionomer sealers; they increased if the sealer contained calcium hydroxide. The diameter of the pores ranged from 5 to 320 ,m and the diameter of the vacuoles ranged from 80 to 500 ,m. The diameter of the vacuoles always exceeded that of the pores. Conclusions, Pores and vacuoles were a consistent finding in set sealers. Their frequency and size depended on the density of the sealer and increased when the sealers contained calcium hydroxide. [source] Spin Echo Analysis of Restricted Diffusion under Generalized Gradient Waveforms for Spherical Pores with Relaxivity and InterconnectionsISRAEL JOURNAL OF CHEMISTRY, Issue 1-2 2003Brett N. Ryland The problem of restricted diffusion in spherical pores is examined under conditions of finite gradient pulse width in pulsed gradient spin echo (PGSE)-NMR experiments. Closed form analytic expressions are derived, and the case of interconnected pores is briefly examined. An expression, based on the pore hopping approximation, is presented that predicts the echo attenuation for diffusion between pores under any gradient waveform. [source] Sintering of Transparent Yttria Ceramics in Oxygen AtmosphereJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Yihua Huang A novel method is reported for the preparation of transparent polycrystalline yttria ceramics in oxygen atmosphere. Zirconia and other additives were added to control the grain growth. Pores can be eliminated clearly at a temperature <1650°C with the grain size around 1 ,m. The grain growth kinetics and the mechanisms controlling grain growth were studied. Sintering in oxygen atmosphere is beneficial for making samples with a big size at low cost and avoiding the posttreatment of samples sintered in vacuum or hydrogen atmosphere. [source] Synthesis of Porous Silicon Nitride with Unidirectionally Aligned Channels Using Freeze-Drying ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002Takayuki Fukasawa Porous silicon nitride with macroscopically aligned channels was synthesized using a freeze-drying process. Freezing of a water-based slurry of silicon nitride was done while unidirectionally controlling the growth direction of the ice. Pores were generated subsequently by sublimation of the columnar ice during freeze-drying. By sintering this green body, a porous silicon nitride with high porosity (over 50%) was obtained and its porosity was controllable by the slurry concentration. The porous Si3N4 had a unique microstructure, where macroscopically aligned open pores contained fibrous grains protruding from the internal walls of the Si3N4 matrix. It is hypothesized that vapor/solid phase reactions were important to the formation mechanism of the fibrous grains. [source] Pores in the Sieve and Channels in the Wall: Control of Paracellular Permeability by Junctional Proteins in Endothelial CellsMICROCIRCULATION, Issue 3 2001GIANFRANCO BAZZONI ABSTRACT Exchange of solutes and ions between the luminal and abluminal compartments of the circulation is critically dependent on the barrier properties of the vascular endothelium. Transport of solutes and fluids occurs along the transcellular and paracellular pathways that are mediated by intracellular vesicles and intercellular junctions, respectively. Although the ability of endothelial cells to dynamically regulate permeability has long been recognized, the precise mechanism and the signaling pathways involved have not been fully elucidated. Finally, current definition of the complex molecular composition of intercellular junctions is expected to explain the difference in permeability between diverse segments of the circulation and possibly to highlight the existence of specific junctional channels. The properties of junctional adhesion molecule-1 (JAM-1) and vascular endothelial cadherin (VE-cadherin), two transmembrane components of interendothelial junctions, are described in detail. [source] Occurrence of antennal glands in antsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 11 2008Robert Renthal Abstract A previous report of the discovery of exocrine glands in the antennal club of queens and workers of Solenopsis invicta Buren, 1972 left open the question of the extent to which similar glands occur in the Formicidae family. We wanted to know if these antennal glands are unique to Solenopsis, or they are found in a wider taxonomic group. Using scanning electron microscopy, we examined the antennae of 41 ant species. Presence of the antennal glands was indicated by a characteristic circumferential ring of pores in a distal antennal segment of workers. Pores were found in the 9th antennal segment of all 26 species of Solenopsis examined. Pores were absent in the following: Monomorium minimum, M. pharaonis, Pheidole sp., Crematogaster sp., Linepithema humile, Forelius sp., Dorymyrmex sp., Paratrechina sp., Oecophylla smaragdina, Campanotus sp., Ectatomma ruidum, E. tuberlatum, and Pseudomyrmex ferruginea. However, pores were found in the antennal club of Tetramorium bicarinatum workers and queens. After KOH digestion of T. bicarinatum antennae, internal canals were observed in both workers and queens, and the canals are connected to spherical reservoirs in queens. T. bicarinatum was the only non- Solenopsis species examined, which showed evidence for antennal glands in the distal funiculus. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Microgel Translocation through Pores under Confinement,ANGEWANDTE CHEMIE, Issue 12 2010Grant Knapp, aber passt: Hydrogelmikropartikel können sich so verformen, dass sie durch Poren mit bis zu 10-mal kleineren Durchmessern passen (siehe Bild) , und dies auch bei Größenverhältnissen und unter Druckgefällen, wie sie bei der physiologischen Filtration in der Niere vorherrschen. Dies macht sie für Anwendungen im Wirkstofftransport interessant. [source] A Spherical 24,Butyrate Aggregate with a Hydrophobic Cavity in a Capsule with Flexible Pores: Confinement Effects and Uptake,Release Equilibria at Elevated Temperatures,ANGEWANDTE CHEMIE, Issue 43 2009Christian Schäffer Moleküle unter Zwang: Der Einschluss einer Anordnung aus 24,organischen Butyrat-Einheiten (siehe Bild), die mit 72,H-Atomen einen bemerkenswert großen hydrophoben Hohlraum umschließen, in einer porösen Kapsel führt zu interessanten Wechselwirkungen zwischen den eingesperrten Butyraten. Bei Temperaturerhöhung wird die ,Quarantäne" aufgehoben und die Gastspezies können leichter kommen und gehen. [source] Unusual Magnetic Properties of Size-Controlled Iron Oxide Nanoparticles Grown in a Nanoporous Matrix with Tunable Pores,ANGEWANDTE CHEMIE, Issue 40 2009Sher Alam Dr. Die volle Ladung: Die Verwendung eine Nanosiebs erleichtert die Synthese von kleinen Fe2O3 -Nanopartikeln mit einer einheitlichen Größe zwischen 6.5 und 9.0,nm, die einfach über den Porendurchmesser der Templatmatrix eingestellt werden kann (siehe Bild). So werden auf einem mesoporösen Träger verteilte Nanopartikel erhalten, die trägerfreien Fe2O3 -Nanopartikeln bezüglich ihrer magnetischen Eigenschaften überlegen sind. [source] Pyrolysis of a Three-Dimensional MnII/MnIII Network To Give a Multifunctional Porous Manganese Oxide MaterialCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2010Sanjit Nayak Dr. Pores for thought! Thermolysis of a 3D coordination network of MnII/MnIII produces a novel spongelike morphology of manganese oxide by a degassing mechanism (see picture). This porous material shows high capacitance when used as an anode in a Li-ion battery and efficient catalytic activity for cyclohexene oxidation. [source] Fluorous Pores in Coordination NetworksCHEMISTRY - AN ASIAN JOURNAL, Issue 10 2009Minsul Jang Fluorous nanophase in the pore: Perfluoroalkyl chain-anchored bridging ligands are assembled, upon complexation with Co(NCS)2, into coordination networks with fluorous pores that show fluorophilic/organophobic properties. The perfluoroalkyl chains are considerably disordered and seem to tumble in the pores, forming a nanoscopic pseudo liquid phase in the solid. [source] Formation of Cross-Linked Chloroperoxidase Aggregates in the Pores of Mesocellular Foams: Characterization by SANS and Catalytic PropertiesCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 2 2009Dirk Jung Abstract No escape: The formation of cross-linked chloroperoxidase aggregates (CPO-CLEAs) in the pores of mesocellular foam materials results in active biocatalysts that are more resistant to leaching than the conventional catalyst prepared by physisorption of chloroperoxidase. Small-angle neutron scattering (SANS) experiments clearly confirm that the CPO-CLEAs are located in the pores of the mesocellular foams. [source] Distribution of the Ordovician Fluid in the Tahe Oilfield and Dynamic Response of Cave System S48 to ExploitationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2008LOU Zhanghua Abstract: The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a cross-formational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of Cl, and K++Na+, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified: (1) residual water at the bottom of the cave after oil and gas displacement, (2) residual water in fractures/pores around the cave after oil and gas displacement, and (3) interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br, concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enrichment of oil/gas become weaker, residual water increases, and the salinity and concentration of Br, decrease. At the edge of the main cave, although the wells have a high deliverability at the beginning with a short stable production period and water-free production period. After water breakthrough, the pressure and deliverability drop quickly, and the water content rises quickly. The hydrochemistral characteristics of the produced water are relatively uniform. Wells in the branch caves have a relatively low deliverability at the beginning, with a short stable production period. Water breakthrough appears quickly and then the pressure and deliverability drop quickly. The salinity and concentrations of Cl, and K++Na+ are usually fluctuant or descend slowly in the produced water. Wells in low areas of ancient karst have a low deliverability and a short stable production period. The yield drops quickly and the water content is high, while the characteristics of the produced water may vary significantly well to well. The salinity and concentrations of Cl, and K++Na+ in the produced water are usually fluctuant with a precipitous decline. [source] Application of Electrochemical Impedance Spectroscopy for Fuel Cell Characterization: PEFC and Oxygen Reduction Reaction in Alkaline Solution,FUEL CELLS, Issue 3 2009N. Wagner Abstract The most common method used to characterise the electrochemical performance of fuel cells is the recording of current/voltage U(i) curves. Separation of electrochemical and ohmic contributions to the U(i) characteristics requires additional experimental techniques like electrochemical impedance spectroscopy (EIS). The application of EIS is an approach to determine parameters which have proved to be indispensable for the characterisation and development of all types of fuel cell electrodes and electrolyte electrode assemblies [1]. In addition to EIS semi-empirical approaches based on simplified mathematical models can be used to fit experimental U(i) curves [2]. By varying the operating conditions of the fuel cell and by the simulation of the measured EIS with an appropriate equivalent circuit, it is possible to split the cell impedance into electrode impedances and electrolyte resistance. Integration in the current density domain of the individual impedance elements enables the calculation of the individual overpotentials in the fuel cell (PEFC) and the assignment of voltage loss to the different processes. In case of using a three electrode cell configuration with a reference electrode, one can directly determine the corresponding overvoltage. For the evaluation of the measured impedance spectra the porous electrode model of Göhr [3] was used. This porous electrode model includes different impedance contributions like impedance of the interface porous layer/pore, interface porous layer/electrolyte, interface porous layer/bulk, impedance of the porous layer and impedance of the pores filled by electrolyte. [source] Post-ischaemic activation of kinases in the pre-conditioning-like cardioprotective effect of the platelet-activating factorACTA PHYSIOLOGICA, Issue 3 2009C. Penna Abstract Aim:, Platelet-activating factor (PAF) triggers cardiac pre-conditioning against ischemia/reperfusion injury. The actual protection of ischaemic pre-conditioning occurs in the reperfusion phase. Therefore, we studied in this phase the kinases involved in PAF-induced pre-conditioning. Methods:, Langendorff-perfused rat hearts underwent 30 min of ischaemia and 2 h of reperfusion (group 1, control). Before ischaemia, group 2 hearts were perfused for 19 min with PAF (2 × 10,11 m); groups 3,5 hearts were co-infused during the initial 20 min of reperfusion, with the protein kinase C (PKC) inhibitor chelerythrine (5 × 10,6 m) or the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (5 × 10,5 m) and atractyloside (2 × 10,5 m), a mitochondrial permeability transition pore (mPTP) opener respectively. Phosphorylation of PKC,, PKB/A,t, GSK-3, and ERK1/2 at the beginning of reperfusion was also checked. Left ventricular pressure and infarct size were determined. Results:, PAF pre-treatment reduced infarct size (33 ± 4% vs. 64 ± 5% of the area at risk of control hearts) and improved pressure recovery. PAF pre-treatment enhanced the phosphorylation/activation of PKC,, PKB/A,t and the phosphorylation/inactivation of GSK-3, at reperfusion. Effects on ERK1/2 phosphorylation were not consistent. Infarct-sparing effect and post-ischaemic functional improvement induced by PAF pre-treatment were abolished by post-ischaemic infusion of either chelerythrine, LY294002 or atractyloside. Conclusions:, The cardioprotective effect exerted by PAF pre-treatment involves activation of PKC and PI3K in post-ischaemic phases and might be mediated by the prevention of mPTP opening in reperfusion via GSK-3, inactivation. [source] A mutation of ion-conducting pore without effect on ion selectivity of the sodium channelACTA PHYSIOLOGICA, Issue 4 2005Matti Vornanen No abstract is available for this article. [source] The Drosophila nucleoporin gene nup154 is required for correct microfilament dynamics and cell death during oogenesisCYTOSKELETON, Issue 8 2007Maria Giovanna Riparbelli Abstract The Drosophila nucleoporin gene nup154 is required in both male and female germline for successful gametogenesis. Mutant flies lack differentiated sperm and lay abnormal eggs. We demonstrated that the egg phenotype was associated with specific alterations of the actin cytoskeleton at different stages of oogenesis. Actually, mutant egg chambers displayed an abnormal organization of both subcortical microfilaments and cytoplasmic actin bundles, that led to defective nurse cell dumping. TUNEL analysis also showed that the dumpless phenotype was associated with delayed apoptosis. The nup154 gene product was localized by conventional immunofluorescence microscopy to the nuclear envelope in a distinct punctuate pattern, characteristic of nuclear pore complex components. TEM analysis revealed that the protein was mainly distributed along filamentous structures that extended radially on the nuclear side of the pore, suggesting that Nup154 could be an integral component of the basket filaments associated with the nuclear pore complexes. We propose that Nup154 is necessary for correct nuclear pore complex functions and that the proper regulation of the actin cytoskeleton dynamics strongly relies upon nuclear pore integrity. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Caveolin-1 polarization in migrating endothelial cells is directed by substrate topology not chemoattractant gradientCYTOSKELETON, Issue 11 2006Virginie Santilman Abstract Polarization is a hallmark of migrating cells, and an asymmetric distribution of proteins is essential to the migration process. Caveolin-1 is highly polarized in migrating endothelial cells (EC). Several studies have shown caveolin-1 accumulation in the front of migrating EC while others report its accumulation in the EC rear. In this paper we address these conflicting results on polarized localization of caveolin-1. We find evidence for the hypothesis that different modes of locomotion lead to differences in protein polarization. In particular, we show that caveolin-1 is primarily localized in the rear of cells migrating on a planar substrate, but in the front of cells traversing a three-dimensional pore. We also show that a chemoattractant, present either as a gradient or ubiquitously in the medium, does not alter caveolin-1 localization in cells in either mode of locomotion. Thus we conclude that substrate topology, and not the presence of a chemoattractant, directs the polarization of caveolin-1 in motile ECs. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Neuron-specific expression of atp6v0c2 in zebrafish CNSDEVELOPMENTAL DYNAMICS, Issue 9 2010Ah-Young Chung Abstract Vacuolar ATPase (V-ATPase) is a multi-subunit enzyme that plays an important role in the acidification of a variety of intracellular compartments. ATP6V0C is subunit c of the V0 domain that forms the proteolipid pore of the enzyme. In the present study, we investigated the neuron-specific expression of atp6v0c2, a novel isoform of the V-ATPase c-subunit, during the development of the zebrafish CNS. Zebrafish atp6v0c2 was isolated from a genome-wide analysis of the zebrafish mibta52b mutant designed to identify genes differentially regulated by Notch signaling. Whole-mount in situ hybridization revealed that atp6v0c2 is expressed in a subset of CNS neurons beginning several hours after the emergence of post-mitotic neurons. The ATP6V0C2 protein is co-localized with the presynaptic vesicle marker, SV2, suggesting that it is involved in neurotransmitter storage and/or secretion in neurons. In addition, the loss-of-function experiment suggests that ATP6V0C2 is involved in the control of neuronal excitability. Developmental Dynamics 239:2501,2508, 2010. © 2010 Wiley-Liss, Inc. [source] A new interpretation of the female genitalia in Macrocyclops albidus (Copepoda, Cyclopidae)ACTA ZOOLOGICA, Issue 1 2003D. Defaye Abstract The female genital structures of Macrocyclops albidus (Cyclopidae, Eucyclopinae) were studied using light and electron microscopy. The results confirm that the exterior genital area shows only a copulatory pore, located anteromedially on the ventral face of the genital double-somite, and paired gonopores (not directly visible), situated laterally under the P6 plates. An internal seminal receptacle, composed of several parts, is connected to the gonopores by ventro-lateral cuticular extensions or seminal ducts. The lateral site of communication shows a complex set of connections between the seminal receptacle and the oviducts (via the egg-laying ducts). The structure until now designated as ,transverse ducts', visible by transparency on the ventral face, is in fact constituted of internal cuticular thickenings resulting of the fusion of the 6th thoracic somite and the 1st abdominal somite forming the genital double-somite and appearing externally as a part of the suture line; the term ,suture cord' is proposed to designate it. The functioning of the system is explained. [source] Copper impregnated mesoporous activated carbon as a high efficient catalyst for the complete destruction of pathogens in water,ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2008L. John Kennedy Abstract Copper impregnated mesoporous activated carbon catalyst was applied for the elimination of microorganisms in wastewater. The antibacterial activity of the catalyst was determined qualitatively by testing the removal of pathogens in water after contacting with the catalyst. Escherichia coli, Shigella flexneri, Shigella dysenteriae, Shigella sonnei, and Salmonella typhi were taken as the model pathogens in determining the antimicrobial activity of the catalyst. The catalyst developed for this purpose was thoroughly characterized using instrumental techniques such as BET analysis, X-ray diffraction, FTIR spectroscopy, and scanning electron microscope to determine the pore and surface area, structural phases, surface functional groups, and surface morphology respectively. The energy dispersive X-ray analysis carried out confirmed qualitatively the percentage of copper impregnated in the catalyst. The experimental studies revealed that the catalyst was highly efficient and advantageous to be employed for industrial applications because of the nonleacheablity of copper from the catalyst and nonreoccurrence of the pathogens in the treated water. The transmission electron microscopy evidenced the complete cell wall rupture of the microorganisms. All the experimental results revealed that the copper impregnated mesoporous activated carbon exhibited a strong and long term antibacterial activity throughout the studies for repeated cycles. © 2007 American Institute of Chemical Engineers Environ Prog, 2008 [source] Can Russia be Competitive in Agriculture?EUROCHOICES, Issue 3 2003William M. Liefert Summary Can Russia be competitive inAgriculture? Russian agriculture currently is not internationally cost competitive. Since the mid-1990s Russia has imported large volumes of meat, while the grain trade has fluctuated in most years between small net imports and exports. Russia has, however, exported large quantities of key agricultural inputs, including 80 per cent of fertilizer output, mainly to EU countries. Research indicates that Russia has a comparative advantage in producing grain compared to meat, but also a comparative advantage in producing agricultural inputs compared to agricultural outputs. The expected real appreciation of the Russian rouble vis-à-vis Western currencies should further damage Russia's cost competitiveness in meat and grain, but this should be offset by modest productivity growth. An expected rise in consumer income, deriving from relatively high annual GDP growth of about 4,5 per cent, should also stimulate demand for meat imports. In spring 2003, Russia imposed tariff rate quotas on its imports of beef and pork, and a pure quota on imports of poultry. For other agricultural commodities, Russia is pushing in its WTO accession negotiations for allowable agricultural import tariffs that are higher than current levels. Taking these changes together, it is likely that Russia will continue as a big meat importer for about the next ten years,with tariff rate quotas probably determining the level of meat imports,and will become a moderate grain exporter. L'agriculture russepourrait-elle être compétitive ? Actuellement, l'agriculture russe n'est pas compétitive. La Russie a importé de gros volumes de viande depuis le milieu des années 90, tandis que la balance des échanges de céréales oscillait entre les faibles excédents et les faibles déficits. Cependant, la Russie est grande exportatrice d'agro-fournitures dont, en particulier, 80% de sa production d'engrais, principalement vers l'Europe. On montre ici que l'avantage comparatif de la Russie se situe dans les céréales plutôt que dans la viande et, surtout, dans les agro-fournitures plutôt que dans les denrées agricoles. La remontée, à laquelle il faut s'attendre, du rouble vis à vis des devises occidentales, devrait encore diminuer la compétitivité de la Russie en matière de viandes et de céréales, ce qui devrait être compensé par des gains de productivité même faibles. La hausse attendue des revenus des consommateurs, engenderée par une croissance élevée du revenu national, de l'ordre de 4 à 5% par an, devrait aussi stimuler la demande de viande importée. Au printemps 2003, la Russie s'est dotée d'un système de droits sur ses importations hors quotas de viande de bæuf et de pore, ainsi que d'un quota d'importation pour les produits avicoles. En ce qui conceme les autres produits agricoles, dans le cadre des négociations relatives à son entrée dans l'OMC, la Russie s'efforce d'obtenir l'autorisation d'augmenter les taxes à l'importation par rapport à leur niveau actuel. Au total done, à un horizon de l'ordre de dix ans, il est probable que la Russie reste un gros importateur de viandes - le niveau des taxes sur le hors quotas déterminant les niveaux d'importation -, et un modeste exportateur de céréales. Kann Russland auf dem Agrarsektorwettbewerbsfähig sein? Die russische Landwirtschaft ist hinsichtlich der Kosten momentan nicht international wettbewerbsfähig. Seit Mitte der 1990er importiert Russland große Mengen an Fleisch, während der Getreidehandel in den meisten Jahren zwischen geringen Nettoimporten und -exporten schwankte. Russland hat jedoch große Mengen an wichtigen landwirtschaftlichen Vorieistungen, unter anderem 80% seiner Düngerproduktion, hauptsächlich in EU-Länder exportiert. Forschungsergebnisse weisen darauf hin, dass Russland in der Produktion von Getreide verglichen mit Fleisch einen komparativen Vorteil besitzt; dies trifft jedoch ebenfalls auf die Produktion von landwirtschaftlichen Vorieistungen verglichen mit landwirtschaftlichen Endprodukten zu. Es ist anzunehmen, dass die erwartete reale Aufwertung des russischen Rubel gegenüber den westlichen Währungen eine zusätzliche Verschlechterung der russischen Wettbewerbsfähigkeit hinsichtlich der Kosten im Bereich Fleisch und Getreide nach sich zieht; dies sollte sich jedoch durch ein moderates Produktivitätswachstum ausgleichen. Der erwartete Anstieg der Verbrauchereinkommen, der sich aus dem relativ hohen jährlichen Bruttoin-landsproduktzuwachs von ca. 4,5 Prozent ableitet, sollte sich ebenfalls stimulierend auf die Nachfrage nach Fleischimporten auswirken. Im Frühjahr 2003 führte Russland Zolltarifkontingente für seine Schweine- und Rindfleischimporte ein und belegte seine Geflügelfleischimporte mit einem Importkontingent. Im Hinblick auf weitere Agrarerzeugnisse drängt Russland in den WTO-Beitrittsverhandlungen darauf, höhere Einfuhrzölle als die gegenwärtig geltenden zuzulassen. In Anbetracht all dieser Veränderungen ist es wahrscheinlich, dass Russland auch für die kommenden zehn Jahre große Mengen an Fleisch importieren,wobei möglicherweise Zolltarifkontingente die Menge bestimmen werden,und sich zu einem mäßigen Getreideexporteur entwickeln wird. [source] Solvothermal Synthesis, Crystal Structure, and Thermal Stability of Three-Layered Thioantimonate(III) Complexes: [Ni(C3H10N2)3]Sb4S7, [C4H14N2]Sb8S13·H2O, and [C6H18N2]Sb10S16·H2OEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2007Meng Zhang Abstract Three new thioantimonate(III) complexes [Ni(1,2-PDA)3]Sb4S7 (1) (1,2-PDA = 1,2-propanediamine), [dmenH22+]Sb8S13·H2O (2) (dmen = N,N -dimethylethylenediamine), and [deenH22+]Sb10S16·H2O (3) (deen = N,N -diethylethylenediamine), prepared under solvothermal conditions, have been characterized by single-crystal X-ray diffraction, elemental analysis, and DTA-TG measurements. In compound 1, a rectangle-like Sb16S16 heteroring whose dimensions are about 8.1,×,14.7 Å is observed, this is the largest reported pore in layered thioantimonates to date. Further condensation of the Sb16S16 heterorings resulted in an unprecedented framework of the five-atom thick SbxSyn, layer. In 2, a new member of SbnSn (n = 2, 3, 4, 8, 16, 30, 31, 32) heterocycles Sb15S15 heteroring has been obtained as the first example. In compound 3, the most particular feature is that when the secondary Sb,S bonds are considered the Sb2 atom becomes sevenfold coordinated.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] | |||||||||||||||||||||||||||||||||||||||||||||||||