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M Diameter (m + diameter)
Selected Abstracts5-Hydroxytryptamine-induced microvascular pressure transients in lungs of anaesthetized rabbitsACTA PHYSIOLOGICA, Issue 2 2001N. Sen We determined lung microvascular pressure transients induced by 5-hydroxytryptamine (5HT), by the micropuncture technique. We mechanically ventilated anaesthetized (halothane 0.8%), open-chested rabbits, in which we recorded pulmonary artery (PA), left atrial (LA) and carotid artery pressures and cardiac output. For 4-min periods of stopped ventilation, we constantly inflated the lung with airway pressure of 7 cmH2O, then micropunctured the lung to determine pressures in arterioles and venules of 20,25 ,m diameter. An intravenous bolus infusion of 5HT (100 ,g), increased total pulmonary vascular resistance by 59%. Prior to 5HT infusion, the arterial, microvascular and venous segments comprised 30, 50 and 19% of the total pulmonary vascular pressure drop, respectively. However 14 s after 5HT infusion, the PA-arteriole pressure difference (arterial pressure drop) increased 46%, while the venule-LA pressure difference (venous pressure drop) increased >100%. The arteriole,venule pressure difference (microvascular pressure drop) was abolished. The increase in the arterial pressure drop was maintained for 4.8 min, whereas the increased venous pressure drop reverted to baseline in <1 min. We conclude that in the rabbit lung in situ, a 5HT bolus causes sustained arterial constriction and a strong but transient venous constriction. [source] Preparation and evaluation of composite electromagnetic wave absorbers made of aluminum fine particles dispersed in polystyrene mediumELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2010Norizumi Asano Abstract We developed composite electromagnetic wave absorbers consisting of dispersed aluminum fine particles in a polystyrene medium and evaluated their properties in order to realize single-layer electromagnetic wave absorbers with good absorption in the gigahertz region. Polystyrene particles with two diameters (approximately 200 ,m and 1 ,m) and fine aluminum particles were mixed by mechanical milling. The mixture was heated above the melting point of polystyrene and then cooled naturally in air. The frequency characteristics of the complex relative permeability and the complex relative permittivity were calculated from the values of the scattering parameters of a coaxial line loaded with a sample of a toroidal-core shape. Both the diamagnetism and the magnetic loss increased in proportion to the volume mixing ratios of aluminum particles up to approximately 34 vol for samples made of polystyrene particles with approximately 200 ,m or 1,m diameter. The diamagnetism was almost frequency-independent and the magnetic loss decreased with increasing frequency for all samples. These results were in agreement with qualitative theoretical prediction. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 93(1): 30, 40, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10169 [source] Evaluation of a new fiber-reinforced resin compositeJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006S. Suzuki Abstract Efficacy of the usage of an experimental fiber-reinforced composite (FRC) on mechanical properties of an indirect composite was investigated by means of three-point bending and Charpy impact tests. Bond strength between the FRC and the indirect composite was also evaluated by tensile testing. The FRC consisted of a matrix resin with 25% silanized milled glass fiber (11-,m diameter, 150-,m length) and 5% colloidal silica. The values of strain of proportional limit, total strain, and fracture energy of the FRC during the bending test (1.2%, 10.4%, and 41.6 × 10,3 J) were significantly higher than those of the indirect composite (0.1%, 2.5%, and 11.9 × 10,3 J). The impact strengths of the 1-mm specimens with FRC ranged from 15.2 to 15.9 kJ/m2, and were significantly higher than that of the control (3.1 kJ/m2). The 2-mm specimens showed significant difference from the control when the FRC thickness was equal or greater than 0.5 mm. The bond strength after the thermocycling was 15.2 MPa, and all of the specimens exhibited cohesive fracture inside the indirect composite. Based upon the results, it was concluded that the FRC tested in this study improved toughness and impact resistance of the indirect composite. The interfacial bonding between the FRC and the indirect composite was strong enough to prevent delamination. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Muscle fibre types and size distribution in sub-antarctic notothenioid fishesJOURNAL OF FISH BIOLOGY, Issue 6 2000D. A. Fernandez The presumptive tonic muscles fibres of Cottoperca gobio, Champsocephalus esox, Harpagifer bispinis, Eleginops maclovinus, Patagontothen tessellata, P. cornucola and Paranotothenia magellanica stained weakly or were unstained for glycogen, lipid, succinic dehydrogenase (SDHase) and myosin ATPase (mATPase) activity. Slow, intermediate and fast twitch muscle fibres, distinguished on the basis of the pH stability of their mATPases, showed intense, moderate and low staining activity for SDHase, respectively. Slow fibres were the major component of the pectoral fin adductor profundis muscle. The proportion of different muscle fibre types varied from the proximal to distal end of the muscle, but showed relatively little variation between species. The myotomes contained a lateral superficial strip of red muscle composed of presumptive tonic, slow twitch and intermediate fibres, thickening to a major wedge at the horizontal septum. All species also had characteristic secondary dorsal and ventral wedges of red muscle. The relative abundance and localization of muscle fibre types in the red muscle varied between species and with body size in the protandric hermaphrodite E. maclovinus. The frequency distribution of diameters for fast twitch muscle fibres, the major component of deep white muscle, was determined in fish of a range of body sizes. The absence of fibres <20 ,m diameter was used as a criterion for the cessation of muscle fibre recruitment. Fibre recruitment had stopped in P. tessellata of 13·8 cm LT and E. maclovinus of 32·8 cm LT, equivalent to 49 and 36·5% of their recorded maximum sizes respectively. As a result in 20-cm P. tessellata, the maximum fibre diameter was 300 ,m and 36% of fibres were in excess of 200 ,m. The unusually large maximum fibre diameter, the general arrangement of the red muscle layer and the extreme pH lability of the mATPase of fast twitch fibres are all common characters of the sub-Antarctic and Antarctic Notothenioids, including Cottoperca gobio, the suggested sister group to the Notothenidae. [source] The kinetics of the reduction of iron oxide by carbon monoxide mixed with carbon dioxideAICHE JOURNAL, Issue 4 2010C. D. Bohn Abstract Results are reported for the repeated reduction of iron oxide particles, 300,425 ,m diameter, by a mixture of CO, CO2, and N2 in a fluidized bed of 20 mm internal diameter. The conclusions were as follows: (1) Reduction of either Fe2O3 to Fe3O4 or of Fe3O4 to Fe0.947O is first-order in CO. (2) With the particle sizes used, the rates of the reduction reactions are controlled by intrinsic chemical kinetics. Activation energies and pre-exponential factors are reported. (3) The first cycle gave anomalous results, but (a) the rate of reduction of Fe2O3 to Fe3O4 remained constant over cycles 2,10; (b) the rate of reduction of Fe3O4 to Fe0.947O declined by 60,85% over cycles 2,10. (4) The rates of reduction declined with solids conversion down to zero at 80% conversion. The rates were incorporated into a conventional model of a fixed bed, which was used to predict, satisfactorily, the reduction behavior of iron oxide. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Renal sexual segment of the Cottonmouth snake, Agkistrodon piscivorous (Reptilia, Squamata, Viperidae)JOURNAL OF MORPHOLOGY, Issue 6 2008David M. Sever Abstract The seasonal variation of the renal sexual segment (RSS) of males of the Cottonmouth snake, Agkistrodon piscivorous, is described using light and electron microscopy. This study is the first to describe the ultrastructure of the RSS of a viper (Viperidae) and only the fourth on a snake. Renal sexual segments from males collected February to May and from August to November are similar in appearance. The cells are eosinophilic and react with periodic acid/Schiff procedure (PAS) for neutral carbohydrates and bromphenol blue (BB) for proteins. At the ultrastructure level, the cells contain large (2 ,m diameter), electron-dense secretory granules and smaller vesicles with a diffuse material, and these structures abut against the luminal border and upon clear vacuoles continuous with intercellular canaliculi. Evidence was found for both apocrine and merocrine processes of product release. In June and July, the RSS are significantly smaller in diameter, largely basophilic, and have only scattered granules that are PAS+ and BB+. Cytologically, the RSS from June to July lack electron-dense secretory granules and the smaller vesicles with diffuse material. Numerous condensing vacuoles and abundant rough endoplasmic reticulum, however, indicate that active product synthesis is occurring. This is the first report of significant seasonal variation in the histology and ultrastructure of the RSS of a snake, although such reports exist for lizards. The seasons when the RSS is most highly hypertrophied correspond to the fall and spring mating seasons of A. piscivorous, as determined by other studies. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source] Axial mixing in modern packings, gas, and liquid phases: II.AICHE JOURNAL, Issue 1 2000Two-phase flow Axial mixing measurements of air and water under two-phase flow conditions were made in a large-scale packed column (0.43 m diameter) using tracer experiments. Part I of this article dealt with single-phase mixing in the same column, with the same internals. Four packings were studied: 25.4-mm ceramic Raschig rings, 25.4-mm metal Pall rings, Sulzer BX structured packing, and Flexipac 2 structured packing. Air and water flowed countercurrently through the column at atmospheric pressure and at gas rates varying from 0.25 kg/m2·s up to the flooding point, and liquid rates from 3.25 to 8.5 kg/m2 ·s. A diffusion-type model served to reproduce the experimental response curves obtained for both phases. The results confirmed previous observations for first-generation packings: axial mixing in the gas increases with both gas and liquid rates, whereas liquid-phase axial mixing is a decreasing function of liquid rate and is insensitive to gas rate up to the flooding point. It was also found that the BX packing produces the least mixing in both phases. The largest mixing effects in the gas phase are found for the Raschig rings, and the largest mixing effects for the liquid phase are found for Flexipac 2. Correlations were developed to reproduce the results, yielding an average ±22% difference between experimental and correlated data. [source] INTERCOLONIAL VARIABILITY IN MACROMOLECULAR COMPOSITION IN P-STARVED AND P-REPLETE SCENEDESMUS POPULATIONS REVEALED BY INFRARED MICROSPECTROSCOPY,JOURNAL OF PHYCOLOGY, Issue 5 2008Philip Heraud Macromolecular variability in microalgal populations subject to different nutrient environments was investigated, using the chlorophyte alga Scenedesmus quadricauda (Turpin) Bréb. as a model organism. The large size of the four-cell coenobia in the strain used in this study (,35 ,m diameter) conveniently allowed high quality spectra to be obtained from individual coenobia using a laboratory-based Fourier transform infrared (FTIR) microscope with a conventional globar source of IR. By drawing sizable subpopulations of coenobia from two Scenedesmus cultures grown under either nutrient-replete or P-starved conditions, the population variability in macromolecular composition, and the effects of nutrient change upon this, could be estimated. On average, P-starved coenobia had higher carbohydrate and lower protein absorbance compared with P-replete coenobia. These parameters varied between coenobia with histograms of the ratio of absorbance of the largest protein and carbohydrate bands being Gaussian distributed. Distributions for the P-replete and P-starved subpopulations were nonoverlapping, with the difference in mean ratios for the two populations being statistically significant. Greater variance was observed in the P-starved subpopulation. In addition, multivariate models were developed using the spectral data, which could accurately predict the nutrient status of an independent individual coenobium, based on its FTIR spectrum. Partial least squares discriminant analysis (PLS-DA) was a better prediction method compared with soft independent modeling by class analogy (SIMCA). [source] Controlling the Size and Morphology of TiO2 Powder by Molten and Solid Salt SynthesisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2008Banasri Roy Nano and submicrometer scale titanium oxide (TiO2) powders were synthesized by solid and molten salt synthesis (SSS and MSS) from amorphous titanium hydroxide precipitate. Sodium chloride (NaCl) and dibasic sodium phosphate (Na2HPO4·2H2O, DSP) separately or as mixture with different weight ratios were used as the salts. At the eutectic salt composition (20% DSP/80% NaCl), the microstructure and phase composition of the TiO2 was changed from equiaxed nanoparticles of anatase with size ,40,50 nm, to mixed microstructure of bundle and acicular particles of rutile with 0.05,0.2 ,m diameter, 6,10 ,m length, and aspect ratio 20,60 depending on treatment time and temperature. At high temperature (825°C) and long time (30 h), microstructural differences were significant for the powders treated with different salts. Particle morphologies ranged from equiaxed, to acicular, to bundles, to nanofibers with very high aspect ratio. At lower treatment temperature (725°C) for shorter time (3 h), the morphology of the products did not change with different salt compositions, but the crystallite sizes changed appreciably. Different starting titanium precursors influenced particle size at lower temperature and time. Titanium hydroxide heat treated without salt resulted in significant grain growth and fused secondary particles, as compared with more finely separated and lightly agglomerated powders resulting from SSS and MSS treatments. [source] Morphology and reproduction of Nipponomysella subtruncata (Yokoyama), a galeommatoidean bivalve commensal with the sipunculan Siphonosoma cumanense (Keferstein) in JapanJOURNAL OF ZOOLOGY, Issue 4 2001J. Lützen Abstract The shell and anatomy of Nipponomysella subtruncata is described. The bivalve is attached singly or in groups of up to nine on Siphonosoma cumanense, a burrowing intertidal sipunculan in south-west Japan. The species is a protandrous hermaphrodite. Specimens 1.4,2.5 mm long are males, which between 2.1 and 3 mm in length reverse sex and remain females. Reproduction peaks in summer and the annual number of clutches is small. Ripe oocytes, 84,88 ,m diameter, are spawned into the suprabranchial cavity where they develop into 107-,m-long straight-hinged veligers. Following a planktotrophic period of unknown duration, the c. 360-,m-long spat normally settle upon and attach to the shells of larger, predominantly female, individuals. At a length of 1,1.6 mm they detach again and live separately thereafter. Sperm are transferred in spermatophores and stored within paired, mushroom-shaped receptacles located posteriorly in the female's suprabranchial cavity. The receptacles first appear in large males or in specimens in the process of reversing sex. Stored sperm probably survive long enough to fertilize more than one clutch. The anatomy of Nipponomysella is characteristic of the Montacutidae, and is of especial interest because of the unique structure of the sperm receptacles. [source] 3D MR angiography of intratumoral vasculature using a novel macromolecular MR contrast agentMAGNETIC RESONANCE IN MEDICINE, Issue 3 2001Hisataka Kobayashi Abstract Noninvasive methods to visualize blood flow in the intratumoral vasculature have not previously been studied. In the present study, the use of a novel intravascular MR contrast agent with a generation-6 polyamidoamine dendrimer core (G6-(1B4M-Gd)192; MW: 175kD) was investigated, and the vasculature in experimental tumors was visualized using 3D MR angiography (MRA). Xenografted tumors in nude mice of two different histologies,KT005 (human osteogenic sarcoma) and LS180 (human colon carcinoma),were used to obtain 3D MRA using G6-(1B4M-Gd)192 and Gd-DTPA. The contrast MR sectional images were correlated with the corresponding histological sections. The intratumoral vasculature in the KT005 tumor was clearly visualized by 3D MRA, which became more evident with the growth of the tumor xenograft. In contrast, the intratumoral vasculature in the LS180 tumor was sparser and much less developed than that in KT005 tumors. Blood vessels with a diameter as small as 100 ,m based on histology were visualized using 0.033 mmol Gd/kg of G6-(1B4M-Gd)192. In conclusion, intratumoral vasculature with a 100-,m diameter was visualized better using 3D MRA with G6-(1B4M-Gd)192 than with Gd-DTPA. Magn Reson Med 46:579,585, 2001. © 2001 Wiley-Liss, Inc. [source] Extent of thermal ablation suffered by model organic microparticles during aerogel capture at hypervelocitiesMETEORITICS & PLANETARY SCIENCE, Issue 10 2009M. J. Burchell Commercial polystyrene particles (20 ,m diameter) were coated with an ultrathin 20 nm overlayer of an organic conducting polymer, polypyrrole. This overlayer comprises only 0.8% by mass of the projectile but has a very strong Raman signature, hence its survival or destruction is a sensitive measure of the extent of chemical degradation suffered. After aerogel capture, microparticles were located via optical microscopy and their composition was analyzed in situ using Raman microscopy. The ultrathin polypyrrole overlayer survived essentially intact for impacts at ,1 km s,1, but significant surface carbonization was found at 2 km s,1, and major particle mass loss at ,3 km s,1. Particles impacting at ,6.1 km s,1 (the speed at which cometary dust was collected in the NASA Stardust mission) were reduced to approximately half their original diameter during aerogel capture (i.e., a mass loss of 84%). Thus significant thermal ablation occurs at speeds above a few km s,1. This suggests that during the Stardust mission the thermal history of the terminal dust grains during capture in aerogel may be sufficient to cause significant processing or loss of organic materials. Further, while Raman D and G bands of carbon can be obtained from captured grains, they may well reflect the thermal processing during capture rather than the pre-impact particle's thermal history. [source] Longitudinal and Radial Gradients of PO2 in the Hamster Cheek Pouch MicrocirculationMICROCIRCULATION, Issue 3 2008Helena Carvalho ABSTRACT Objectives: The aim of this study was to determine longitudinal and radial gradients in oxygen tension (PO2) in microvessels of the hamster cheek pouch. Methods: We measured PO2 using the phosphorescence-quenching method in two orders of arterioles (45.8 ± 5.5 and 19.9 ± 1.8 , m diameter), capillaries, and two orders of venules (50.5 ± 3.4 and 21.4 ± 2.0 , m diameter) in order to determine the longitudinal PO2 gradient. At the arteriolar and venular sites, we also measured PO2 at four different sites for an analysis of radial PO2 gradients: centerline, inside wall (larger arteriole and venule only), outside wall, and interstitium. We used 10 hamsters weighing 115 ± 27 g anesthetized with pentobarbital intraperitoneally and maintained with alpha-chloralose intravenously. The cheek pouch was everted and a single-layered preparation was studied by intravital microscopy. Albumin-bound Pd-porphyrin was infused into the circulation and excited by flash illumination at 10 Hz, with a rectangular diaphragm limiting the excitation field to 5 × 25 , m. Results: In the longitudinal direction, intravascular PO2 decreased significantly (P < 0.01) from large arterioles (39.5 ± 2.3 mmHg) to small arterioles (32.2 ± 0.3 mmHg), then to capillaries (30.2 ± 1.8 mmHg), and on to small venules (27.3 ± 2.1 mmHg) and large venules (25.5 ± 2.2 mmHg). In the radial direction, PO2 decreased significantly (P < 0.01) in and around larger arterioles, and to a lesser extent, around the smaller ones (P < 0.05). There was no significant PO2 gradient, longitudinal or radial, associated with venules. The PO2 difference from the centerline to the outside wall in large arterioles was 8.3 ± 1.4 mmHg, and most of the decline in PO2 in the radial direction was contributed by the intravascular difference (4.7 ± 2.1 mmHg) and only about 1.0 ± 2.7 mmHg by the transmural difference. Conclusions: Our data show that there are large intra-arteriolar radial PO2 gradients, but no large transmural PO2 differences, suggesting that the oxygen consumption of the microvessel wall is not exceptionally high. [source] Characteristics of two-segment lensed fiber collimatorMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010Yu-Cheng Lin Abstract A two-segment lensed fiber collimator using gradient index fiber (GIF) of 140 ,m diameter spliced to a coreless fiber (CLF) of 125 ,m, and a single mode fiber (SMF) is demonstrated. The CLF and GIF are treated as a beam expander and lens, respectively. The complex beam parameter method and ABCD law are applied for theoretical analysis. Both numerical and experimental data are presented for optical characterization of the divergence angle and insertion loss in lateral and axial displacement of the device. The divergence angle of 1.5 degrees is obtained for the wavelength of 1.31 ,m at the GIF length of 180 ± 5 ,m and the CLF length of 350 ,m. The variation of insertion loss due to lateral and axial displacement shows good agreement with theory. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1846,1848, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25353 [source] Insertion loss of lensed fiber collimator with larger gradient-index lens diameterMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2010Yu-Cheng Lin Abstract The insertion loss of lensed fiber collimator using gradient-index fiber of 140-,m diameter spliced to single-mode fiber is investigated. The power transmission equation is applied for theoretical analysis of the insertion loss between a lensed fiber pair. Both numerical and experimental data are presented in axial and lateral displacement. The optimum coupling position 600 ,m for 0.29-pitch lensed fiber and the maximum working distance 1027 ,m for 0.27-pitch lensed fiber are demonstrated. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1235,1238, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25171 [source] An autopsy case of Fabry disease with neuropathological investigation of the pathogenesis of associated dementiaNEUROPATHOLOGY, Issue 5 2008Riki Okeda The pathogenesis of dementia associated with Fabry disease was examined neuropathologically in an autopsy case. The patient was a 47-year-old computer programmer who developed renal failure at the age of 36, necessitating peritoneal dialysis, and thereafter suffered in succession episodic pulmonary congestion, bradyacusia, heart failure, and dementia, before dying of acute myocardial infarction. MRI of the brain demonstrated leuko-araiosis. The CNS parenchyma showed widespread segmental hydropic swelling of axons in the bilateral cerebral and cerebellar deep white matter in addition to neuronal ballooning due to glycolipid storage in a few restricted nuclei and multiple tiny lacunae. Hydropic axonal swelling was also sparsely distributed in the pyramidal tract, pedunculus cerebellaris superior and brachium colliculi inferioris, but wallerian degeneration of these tracts was absent. Additional features included angiopathy of the subarachnoidal arteries due to Fabry disease, such as medial thickening resulting from glycolipid deposition in smooth muscle cells (SMCs) and adventitial fibrosis with lymphocytic infiltration, together with widespread subtotal or total replacement of medial SMCs by fibrosis, associated with prominent intimal fibrous thickening and undulation of the internal elastic membrane of medium-sized (1000,100 ,m diameter) arteries. The findings in this case suggest that axonopathic leukoencephalopathy due to multisegmental hydropic swelling of axons in the bilateral cerebral deep white matter is responsible for the dementia associated with Fabry disease, and may be caused by ischemia resulting from widespread narrowing and stiffening of medium-sized subarachnoidal arteries and progressive heart failure. [source] Instrumentation for Simultaneous Gas and Particle Velocity Measurements at Mach,5,PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 6 2002Francis Micheli Abstract This study deals with re-entry vehicles passing through high-altitude clouds of ice particles. The particles disturb the flow field and are erosive, thereby increasing the turbulent heat flux considerably. Measurements were performed in a blow-down wind tunnel to analyze the effects of a particle field on the flow. The wind tunnel flow was seeded by two aerosols. The first was used for LDV flow velocity measurements. Its size was checked by the analysis of its passage through a plane shock wave. The second aerosol was made of uniform micro-spheres of 200,,m diameter, used to simulated the water droplets. The velocity, feeding and scattering of the latter aerosol need to be accurately measured. The velocities of the flow field and of the micro-spheres were measured simultaneously by laser velocimetry. This paper describes the instruments used to seed, ascertain and measure this flow with two aerosols. [source] A Beam-splitting Device for Use with Fiber-coupled Laser Light Sources for Photodynamic Therapy,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2002Leroy M. Wood ABSTRACT A device that divides light into eight, four or two beams of equivalent power with only minor total power loss was designed, built and tested. The apparatus accepts light from a 200 ,m diameter, 0.16 numerical aperture, silica,silica multimode optical fiber connected to one of several laser light sources for photodynamic therapy (PDT) of cancer. The incorporation of a variable iris diaphragm into the optical couplers allows the power of the beams to be independently set. Each of the beams can be coupled to a 400 or 600 ,m diameter optical fiber to deliver the therapeutic light to the patient. This device is used in our institute for PDT of patients with either numerous small malignant tumors or single tumors with large surface area. [source] The recently established diatom Coscinodiscus wailesii (Coscinodiscales, Bacillariophyta) in Brazilian waters.PHYCOLOGICAL RESEARCH, Issue 2 2001I: Remarks on morphology, distribution SUMMARY Coscinodiscus wailesii Gran et Angst is a large centric diatom (280,500 ,m diameter) from marine phytoplankton, characterized by a cylindrical frustule with flat valvar surface, two marginal rings of rimoportulae on the mantle, and two macrorimoportulae. Cells from cultured and natural populations collected in Paranaguá Bay, Paraná, southern Brazil were observed under light and scanning electron microscopes to verify the populations' correct identity and morphology. In both populations, a typical central rosette or a hyaline area was found in the valvar center. The species' distribution in Brazilian waters was revised, and a discussion on possible vectors of transport was made. Blooms of the species occur sporadically in the coast of Paraná, seeming to affect the local trophic chain. [source] Micromechanics for fiber volume percent with a photocure vinyl ester compositePOLYMER COMPOSITES, Issue 3 2007Richard C. Petersen Micromechanics for fiber volume percent (Vf) from 0.0Vf to 54.0 Vf were conducted using (3 mm long × 9 ,m diameter) high-purity quartz fibers in a visible-light vinyl ester particulate-filled photocure resin. MTS fully articulated four-point bend fixtures were used with a 40 mm test span and 50 × 2 × 2 mm3 sample dimensions. Specimens were tested following the combined modified ASTM standards for advanced ceramics ASTM-C-1161,94 and polymers ASTM-D-6272,00 for modulus, flexural strength, and yield strength. Experimental data provided reliable statistical support for the dominant fiber contribution expressed through the rule-of-mixtures theory as a valid representation of micromechanical physics. The rule-of-mixtures micromechanics described by Vf could explain 92, 85, and 78% of the variability related to modulus, flexural strength, and yield strength respectively. Statistically significant improvements with fiber addition began at 10.3Vf for modulus, 5.4Vf for flexural strength, and 10.3Vf for yield strength, p < 0.05. In addition, correlation matrix analysis was performed for all mechanical test data. An increase in Vf correlated significantly with increases in modulus, flexural strength, and yield strength as measured by the four-point bending test, p < 10,10. All mechanical properties in turn correlated highly significantly with one another, p < 10,9. POLYM. COMPOS., 28:294,310, 2007. © 2007 Society of Plastics Engineers [source] Less-ordered lamellar structure of intercalated poly(L -lactide)/organo-modified montmorillonite hybridsPOLYMER ENGINEERING & SCIENCE, Issue 6 2006Pham Hoai Nam Hybrids of poly(L -lactide)/organophilic clay (PLACHs) have been prepared via a melt-compounding process using poly(L -lactide) (PLLA) and different contents of surface-treated montmorillonite modified with dimethyl dioctadecyl ammonium-salt. The crystalline structures of PLLA and dispersion states of clay particles in those PLACHs were investigated by use of wide-angle X-ray diffraction, small-angle X-ray scattering, transmission electron microscopy (both cross section and replication modes), and polarized optical microscopy. Those structures are viewed from the conformational changes of PLLA chains in the space of a few nanometer widths between silicate galleries to crystalline lamellae of several nanometer thicknesses, and spherulitic textures more than micrometer sizes. After annealing treatments at 115°C for 1 hr, the PLACHs formed coarse-grained spherulitic textures with 40 ,m diameter composed of less-ordered and fragmented lamellae, caused by the reduced mobility of the PLLA chain due to the dispersed clay particles in the PLLA matrix and the intercalation of the PLLA chains in the silicate galleries. The formation of the interfibril structure accompanied by the fragmented lamellae among the dispersed clay particles was examined. POLYM. ENG. SCI., 46:703,711, 2006. © 2006 Society of Plastics Engineers [source] U-Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma,Mass Spectrometry Coupled with Frequency Quintupled Nd-YAG (, = 213 nm) Laser Ablation System: Comparison with LA-ICP-MS Zircon Analyses with a NIST Glass Reference MaterialRESOURCE GEOLOGY, Issue 2 2008Yuji Orihashi Abstract This paper evaluates the analytical precision, accuracy and long-term reliability of the U-Pb age data obtained using inductively coupled plasma,mass spectrometry (ICP-MS) with a frequency quintupled Nd-YAG (, = 213nm) laser ablation system. The U-Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 ,m diameter. For 207Pb/206Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 (n = 280, 95% confidence), which agrees well with the published value of 0.9096. The time-profile of Pb/U ratios during single spot ablation showed no significant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength (, = 213 nm) laser ablation. But 206Pb/238U and 207Pb/235U ages obtained by this method for seven zircon standards are systematically younger than the published U-Pb ages obtained by both isotope dilution,thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion-microprobe (SHRIMP). Greater discrepancies (3,4% younger ages) were found for the 206Pb/238U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation-transport processes of the sample aerosols cannot be neglected. When the 206Pb/238U (= 0.2302) newly defined in the present study is used, the measured 206Pb/238U and 207Pb/235U ages for the seven zircon standards are in good agreement with those from ID-TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP-MS with laser ablation sampling (LA-ICP-MS) zircon analysis, but it is necessary to determine the correction factor for 206Pb/238U by measuring several zircon standards in individual laboratories. [source] Current Loads of Coarse Woody Debris on Southeastern Australian Floodplains: Evaluation of Change and Implications for RestorationRESTORATION ECOLOGY, Issue 4 2002Ralph MacNally Abstract We evaluated the status of coarse woody debris (CWD, fallen wood) on floodplains of the southern Murray-Darling basin of southeastern Australia. The floodplains are dominated floristically by the river red gum Eucalyptus camaldulensis. Aerial survey techniques were used to estimate the amounts of woody debris within 200 m of the channels along 2,442 km of 11 rivers of the system, including the Murray and Darling Rivers and the Darling Anabranch. Aerially based indices were converted into wood volumes by using ground-truthing at a selection of sites; there was a strong correlation between index values and measured wood volume densities. For thickly forested sites such as Barmah, Gunbower Island, and the Ovens floodplains, the aerial method was not useful, so ground measurements at randomly positioned sites within the forests were used. Volumes were translated into mass by using conversion factors drawn from the literature. We estimated that total tonnage on approximately 221,000 ha of floodplain forests was 4.175 ± 0.579 × 106 tonne. In the larger forested blocks (>7,000 ha), mean wood densities ranged between approximately 12 tonne/ha on the lower Goulburn up to approximately 24 tonne/ha at Barmah State Forest. The area-weighted mean for the entire area was approximately 19 tonne/ha. A main purpose of the research was to place these figures into an historical perspective to evaluate implications for restoration. A thorough search of historical documentation revealed that there are no extant data upon which to estimate pre-European settlement levels. We used information from an apparently undisturbed "unmanaged" site in the Millewa forests of southern New South Wales as a basis. Wood density there corresponded to a mean figure of 125 tonne/ha wood-mass density. By using this figure we estimate that CWD levels on the southern Murray-Darling basin may be of the order of 15% of pre-European settlement levels. Full restoration of the 221,000 ha surveyed would require 23.5 ± 0.579 × 106 tonne, which is equivalent to about 600,000 mature (1 m diameter at breast height) river red gum trees or the amount of timber derived from clear felling about 115,000 ha of river red gum forest at current stocking levels. We discuss the implications of this massive deficit and possible short- and long-term solutions. [source] The development of the Schmidt telescopeASTRONOMISCHE NACHRICHTEN, Issue 6 2009G. Wolfschmidt Abstract Bernhard Schmidt (1879,1935) was born in Estonia. After a few years of studying engineering he ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, on behalf of the Hamburg Observatory, he developed a short focal length optical system with a large field of view. For this purpose, Schmidt moved his workshop to the observatory. He succeeded in inventing the "Schmidt telescope" which allows the imaging of a large field of the sky without any distortions. Schmidt's first telescope (spherical mirror diameter 0.44 m, correction plate 0.36 m diameter, aperture ratio 1:1.75, and focal length 0.625 m) has been used since 1962 at the Boyden Observatory in Bloemfontein/South Africa. Apart from his 0.36m telescope, Schmidt produced a second larger one of 0.60m aperture. Shortly after Schmidt's death, the director of the observatory published details on the invention and production of the Schmidt telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope, the "Big Schmidt" (1.26 m), Mount Palomar, USA, was completed in 1948. The 0.80 m Schmidt telescope of Hamburg Observatory, planned since 1936, finished in 1954, is now on Calar Alto/Spain (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dynamic culture of droplet-confined cell arraysBIOTECHNOLOGY PROGRESS, Issue 1 2010Elisa Cimetta Abstract Responding to the need of creating an accurate and controlled microenvironment surrounding the cell while meeting the requirements for biological processes or pharmacological screening tests, we aimed at designing and developing a microscaled culture system suitable for analyzing the synergic effects of extracellular matrix proteins and soluble environments on cell phenotype in a high-throughput fashion. We produced cell arrays deposing micrometer-scale protein islands on hydrogels using a robotic DNA microarrayer, constrained the culture media in a droplet-like volume and developed a suitable perfusion system. The droplet-confined cell arrays were used either with conventional culture methods (batch operating system) or with automated stable and constant perfusion (steady-state operating system). Mathematical modeling assisted the experimental design and assessed efficient mass transport and proper fluidodynamic regimes. Cells cultured on arrayed islands (500 ,m diameter) maintained the correct phenotype both after static and perfused conditions, confirmed by immunostaining and gene expression analyses through total RNA extraction. The mathematical model, validated using a particle tracking experiment, predicted the constant value of velocities over the cell arrays (less than 10% variation) ensuring the same mass transport regime. BrdU analysis on an average of 96 cell spots for each experimental condition showed uniform expression inside each cell island and low variability in the data (average of 13%). Perfused arrays showed longer doubling times when compared with static cultures. In addition, perfused cultures showed a reduced variability in the collected data, allowing to detect statistically significant differences in cell behavior depending on the spotted ECM protein. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Numerical Study on Bubble Formation of a Gas-Liquid Flow in a T-Junction MicrochannelCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2009L. Dai Abstract Bubble emergence in a gas-liquid flow in a T-junction microchannel of 100,,m diameter, operated under a squeezing regime, was simulated with the computational fluid dynamics method. In general, bubble formation in channels includes three stages: expansion, collapse and pinching off. After analyzing and comparing quantitatively the three forces of pressure, surface tension and shear stress acting on the gas thread in the whole process, their effects in the different stages were identified. The collapse stage was the most important for bubble formation and was investigated in detail. It was found that the collapse process was mostly influenced by the liquid superficial velocity, and the rate and time of collapse can be correlated with empirical equations including the liquid superficial velocity, the capillary number and the Reynolds number. [source] Pressure Drop in Liquid-liquid Two Phase Horizontal Flow: Experiment and PredictionCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2005D. P. Chakrabarti Abstract The present study is aimed at an investigation of the pressure drop characteristics during the simultaneous flow of a kerosene-water mixture through a horizontal pipe of 0.025,m diameter. Measurements of pressure gradient were made for different combinations of phase superficial velocities ranging from 0.03,2,m/s such that the regimes encountered were smooth stratified, wavy stratified, three layer flow, plug flow and oil dispersed in water, and water flow patterns. A model was developed, which considered the energy minimization and pressure equalization of both phases. [source] Hospital admissions for respiratory conditions in children and outdoor air pollution in Southwest Milan, ItalyACTA PAEDIATRICA, Issue 8 2010M Giovannini Abstract Aim:, To evaluate whether a relationship exists in hospital admissions for respiratory conditions in children with outdoor pollution in the Southwest Milan, Italy. Methods:, Daily count of hospital admissions for asthma, upper or lower respiratory diseases (LRD) occurred among children aged ,14 years at the San Paolo Hospital during 2007,2008 was recorded. Pollutants included the particular matter of <10 ,m diameter, ozone, carbon monoxide (CO) and nitrogen dioxide (NO2), reported on the same day of admission and 1 up to 5 days before admission. The moving weekly average (MWA) was also considered. Results:, Total respiratory admissions were associated with the same day level of CO (30.6% increase per 1 mg/m3 increase, 95% confidence interval, 3.9,69.9%) and with the MWA of NO2 (9.0% increase per 10 ,g/m3 increase, 1.2,16.8%). The effect of CO was stronger on upper respiratory diseases (URD) (lag 0, 21.3% increase, 6.4,38.3%). The effect of NO2 was stronger on LRD (MWA, 5.3% increase, 0.9,10.2%). Multipollutant models confirmed the role of CO on URD and that of NO2 on LRD. Conclusion:, Carbon monoxide and nitrogen dioxide may be associated with emergency hospital admissions for respiratory conditions among children in Southwest Milan. [source] Comparison of Different Strategies on DNA Chip Fabrication and DNA-Sensing: Optical and Electrochemical ApproachesELECTROANALYSIS, Issue 22 2005Sabine Szunerits Abstract New strategies for the construction of DNA chips and the detection of DNA hybridization will be discussed in this review. The focus will be on the use of polypyrrole as a linker between a substrate and oligonucleotide probes. The modification step is based on the electrochemical copolymerization of pyrrole and oligonucleotides bearing a pyrrole group on its 5, end. This strategy was employed for the immobilization of oligonucleotides on millimeter-sized electrodes, microelectrode arrays, as well as for the local structuring of homogeneous gold surfaces. Our approaches for the localized patterning of gold surfaces will be also discussed. Localized immobilization was achieved by using an electrospotting technique, where a micropipette served as an electrochemical cell where spot sizes with 800,,m diameters were fabricated. The use of a microcell using a Teflon covered metal needle with a cavity of 100,,m resulted in immobilized probe spots of 300,,m. Scanning electrochemical microscopy (SECM) was also used, and surface modifications of 100,,m were obtained depending on the experimental conditions. Different detection methods were employed for the reading of the hybridization event: fluorescence imaging, surface plasmon resonance imaging (SPRI), photocurrent measurements, and voltamperometric measurements using intercalators. Their advantages concerning the various immobilization strategies will also be discussed. [source] | ||||||||||||||||||||||||||||