Secondary Tube Research Articles

ICONE15-10682 ENTRAINMENT OF WATER AROUND A SINGLE ROD IMMERSED IN WATER POOL WITH GAS JET IMPINGEMENT(II)

The occurrence of secondary heat transfer tube failure due to overheating by sodium-water reaction in steam generator of liquid sodium cooled fast breeder reactor has been concerned from the viewpoint of public acceptance. To evaluate the phenomena for the secondary heat transfer tube failure, a sophisticated computer code SERAPHIM has been developed by JAEA. The comparison of simulation results with experimental data to verify the adequacy of SERAPHIM code or to upgrade it are now required. As the first step to verify the adequacy of SERAPHIM code without chemical reactions, a visualization experiment of Ar gas jet impinging a single rod with 20mm in diameter immersed in a water pool was performed in our previous study. The time sequential results showed that the surrounding water is periodically entrained into Ar gas jet because of the organized motions between the gas jet and the surrounding water. The entrained water into gas jet was considered to be effectively contributed to heat transfer characteristics if the single rod is heated. We measured the void fraction around a single rod in the water pool as a basic experiment using the apparatus capable of doing sodium pool experiment to investigate the flow pattern and the water entrainment around a single rod (several millimeters from the rod surface) in this paper. The vertical gas tube with a nozzle at the top was inserted through the bottom of experimental tank. The diameter of nozzle prepared on the top of the tube is 3.5mm. A single horizontal rod immersed in water pool is fixed a distance of 25mm between the nozzle exit and the forward stagnation point of the rod. The Ar gas jet velocity was changed from 17.3m/s to 346m/s. The result of the void fraction reflected the result of the heat transfer experiment that had been reported before was obtained, and a certain prospect of the measurement of the void fraction in sodium pool was obtained.

Thomson scattering from a shock front

We have obtained a Thomson scattering spectrum in the collective regime by scattering a probe beam from a shock front, in an experiment conducted at the Omega laser at the Laboratory for Laser Energetics. The probe beam was created by frequency converting a beamline at Omega to a 2ns pulse of 0.263μm light, focused with a dedicated optical focusing system. The diagnostic system included collecting optics, spectrometer, and streak camera, with a scattering angle of 101°. The target included a primary shock tube, a 20-μm-thick beryllium drive disk, 0.3-μm-thick polyimide windows mounted on a secondary tube, and a gas fill tube. Detected acoustic waves propagated parallel to the target axis. Ten laser beams irradiated the beryllium disk with 0.351μm light at 5×1014W∕cm2 for 1ns starting at to, driving a strong shock through argon gas at ρo=1mg∕cc. The 200J probe beam fired at t=19ns for 2ns, and at t=20.1ns a 0.3ns signal was detected. We attribute this signal to scattering from the shocked argon, before the density increased above critical due to radiative collapse.

Computational Sensitivity Study on Sodium-Water Reaction Phenomenon

Sensitivity studies on Sodium-Water Reaction (SWR), which will take place in a steam generator of Liquid Metal Fast Reactor (LMFR) when a heat transfer tube fails, have been carried out using a multi-dimensional computational code: SERAPHIM. An initial pressure of liquid sodium, an interfacial area density and an evaporation of sodium hydroxide (NaOH) are chosen as a parameter in this study. An influence of the parameter on a development of high temperature zone (>1000°C) and maximum temperature has been investigated from the perspective that one avoids a secondary heat transfer tube failure in a steam generator due to overheating rupture. In the analyses, it is assumed that water vapor leaks into liquid sodium without any barrier for a simplicity. As a result, it is found that the initial pressure and the interfacial area density affect the high temperature zone strongly, whereas they have almost no influence on the maximum temperature in the present configuration. As concerns the evaporation of sodium hydroxide, it influences not on the high temperature zone but on the maximum temperature. The maximum temperature decreases approximately 200°C due to latent heat of the evaporation. It is concluded that the evaporation of sodium hydroxide will be a key phenomenon for maximum temperature investigation in the SWR.

The growth of nanophases in the clean room inside single-wall carbon nanotubes

The interior of single-wall carbon nanotubes is studied by filling fullerenes into the one-dimensional nanospace inside the tubes using different filling methods. Filling from solution is demonstrated as efficient as filling from the vapor phase. Evidence for successful filling comes from a transformation of the encapsulated carbon atoms to a secondary tube centered inside the primary tube. Isotope-labeled fullerenes are used to disentangle the Raman response from the two shells in double-wall carbon nanotubes.

Formation of small-diameter carbon nanotubes from PTCDA arranged inside the single-wall carbon nanotubes

A systematic study was carried out on the doping of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) to the single-wall carbon nanotubes (SWNTs). After the doping reaction, the interior space of SWNTs was fully filled with the dopant. The heat treatment at high temperature in vacuum of this PTCDA-filled SWNTs induced new Raman signals ranging between 300 and 400 cm −1, which was assigned to the radial breathing mode of vibration associated with the inner tubes. Furthermore, transmission electron microscopy clearly showed the existence of one-dimensionally arranged PTCDA molecules in the tube and the secondary inner tubes formed after the high-temperature treatment.

Raman scattering analysis of changes induced by chemical treatment of double-walled carbon nanotubes

Here we examine the changes in double-walled carbon nanotubes with two chemical treatments using Raman scattering spectroscopy at an excitation of 632.8 nm (1.96 eV). The nanotubes were acid treated then subsequently treated with phosphorus pentasulfide (a mild electrophillic catalyst). While the treatment process maintains the integrity the nanotubes, Raman analysis indicates the outer shells loose their electron–phonon resonance and metallic character, leaving only the tangential mode from the secondary (inner) tubes. After chemical treatment the strongly up-shifted G-band, at 1585 cm −1, has been designated as secondary semiconductor tubes, exhibiting resonant scattering via E 22 s

Improved Reliability of Measurement of Lactate Dehydrogenase by IFCC Method in Heparin Plasma

Our laboratory recently reported (1) an excessively high frequency of duplicate errors in measurements of lactate dehydrogenase (LD; l-lactate:NAD+ oxidoreductase; EC 1.1.1.27) activity with the Roche IFCC-recommended method (2). This unacceptably high frequency of duplicate errors was found with various Hitachi analyzers (Roche GmbH) with primary lithium-heparin tubes with plasma separator from Becton Dickinson but not with serum or EDTA plasma. Such duplicate errors were not seen with the German- and French-recommended LD methods (3)(4), nor were such duplicate errors seen when nonevacuated heparin tubes from Sarstedt were used (5). In addition to the effects of methods, we investigated the effects of sample preparation, method modifications, mixing procedures, and the use of different lithium-heparin-containing tubes with and without plasma separator, lithium-heparin glass and plastic tubes, different lithium-heparin concentrations, and subsampling into secondary tubes. The results of all of these experiments are shown in Table 1 of the Data Supplement that accompanies the online version of this Technical Brief at http://www.clinchem.org/content/vol51/issue1/. Previously, we showed that the high frequency of duplicate errors was not caused by carryover from reagents for other tests and was not restricted to one specific type of Hitachi analyzer (1). In the present study, we demonstrate that the high frequency of duplicate errors is not restricted to the use of Roche reagents, confirming that the duplicate errors are caused by the combination of evacuated lithium-heparin tubes from Becton Dickinson …

Extending low-NO x operating range of a lean premixed–prevaporized gas turbine combustor by reaction of secondary mixtures injected into primary stage burned gas

Reactions of lean to ultra-lean premixed mixtures injected into the hot burned gas that was produced in the lean-burn primary stage can be successfully used for extending the ultra-low NO x operating range of a gas turbine combustor. A tubular lean–lean two-stage model combustor for a simple cycle 200 kW gas turbine was designed based on this concept. Two secondary mixture injection tubes with a flow deflector at the exit, extending into the primary combustion zone, were used to inject lean premixed–prevaporized kerosene–air mixtures of various fuel concentrations into the volumes of hot burned gas produced by the lean-burn primary burners. The emissions and combustion characteristics were evaluated at 600 K inlet air temperature and 0.8 MPa pressure for two sizes of mixture injection tubes. With increasing the secondary fuel flow rate while maintaining the primary mixture equivalence ratio fixed, the NO x concentration remained at the level achieved for no secondary fuel (i.e., single stage combustion) for a while before it gradually increased. A still further increase in the secondary mixture equivalence ratio beyond the primary mixture equivalence ratio finally resulted in a steep increase in NO x emissions due to enhanced thermal NO x formation. It was shown that at proper air splits, high combustion efficiency was achieved while maintaining the NO x emissions in a single digit over a very wide range of overall equivalence ratios. It was found that combustion oscillation hardly occurred in the lean–lean two-stage combustion provided that the primary mixture was lean enough, though severe combustion oscillation occurred at greater overall equivalence ratios (typically >0.8) in the single stage combustion.

Technique to Make Nano Carbon Tubes Buried Inside Rubber Composite Visible Using Femtosecond Pulse Laser Ablation

A method to observe the dispersion structure of carbon nanotubes buried inside a molding composite is described in this communication. The idea is that by utilizing the difference in ablation temperature between the tubes and the composite material, only the composite material, which has a lower ablation temperature, is ablated and buried tubes appear. This was applied to a rubber composite mixed with vapor-grown carbon fibers. A 150-fs pulse laser was prepared as an ablation source. In the ablation images observed with a field-emission secondary electron microscope, linear tubes, clusters, and connections of the tubes could be easily found in their original state.

Sill complex geometry and internal architecture: a 3D seismic perspective

Abstract Seismic volume visualization techniques demonstrate that saucer-shaped sill complexes consist of a series of radiating principal flow units rising from an inner saucer and fed by principal magma tubes. Such flow units contain smaller scale secondary flow units, each being fed by a secondary magma tube branching from the principal magma tube. This pattern is repeated down to scales of approximately 100 m with successively smaller flow units being fed from magma tubes repeatedly branching from higher order tubes. The data demonstrates that each sill complex is independently fed from a centrally located point source, that sills grow by climbing from the centre outwards and that peripheral dyking from the upper surface is a common feature. These features suggest a laccolith emplacement style involving peripheral fracturing and dyking during inner saucer growth and thickening.

Reliability of IFCC Method for Lactate Dehydrogenase Measurement in Lithium-Heparin Plasma Samples

In a recent Technical Brief on the IFCC-recommended method for lactate dehydrogenase (LD) measurement, Bakker et al. (1) questioned the reliability of this method for heparin samples. According to their findings, the IFCC method produced an excessive frequency of significantly discordant duplicate measurements (17.8%; 27 of 152 samples) compared with the formerly applied French Society (SFBC)-recommended method (1.4%; 2 of 140 samples). Neither increased centrifugation time and speed or the use of plasma separators to reduce the plasma contamination with blood cells, nor LD measurements without concurrent measurements of other analytes to eliminate possible interferences lowered the reported high rate of duplicate errors. The problem was also not attributable to the clinical chemistry analyzer because measurements on both Hitachi 911 and 717 analyzers (Roche Diagnostics GmbH) showed results similar to those obtained with the previously used Modular analyzer (Roche Diagnostics GmbH). Only when serum samples or secondary tubes for centrifuged plasma samples were used was there a significantly lower frequency of duplicate errors: 2.6% (3 of 114) for serum and 1.1% (1 of 94) for secondary plasma tubes. The authors pointed out that the differences in buffer composition of the IFCC (pH 9.40 ± 0.05) (2) and SFBC (pH 7.4–7.8) methods influenced the integrity of platelets and erythrocytes. In this case, the presence of cells might play a role in the high frequency of duplicate errors. We have been measuring LD activity on three Roche Hitachi 917 analyzers according to the recommendations of the IFCC (2) in our laboratory since February 2003. The within-run imprecisions (CV) for a heparin-plasma sample (n = 20) were 0.8% (197.4 U/L) and 0.7% (321.3 U/L), and the between-run CV were 1.4% for the Roche Precipath U (178.3 U/L; n = 28) and 1.1% for the Roche Precinorm U calibrators (241.0 U/L; n = 28). …

Geometry and growth of sill complexes: insights using 3D seismic from the North Rockall Trough

Doleritic sill complexes, which are an important component of volcanic continental margins, can be imaged using 3D seismic reflection data. This allows unprecedented access to the complete 3D geometry of the bodies and an opportunity to test classic sill emplacement models. The doleritic sills associated with basaltic volcanism in the North Rockall Trough occur in two forms. Radially symmetrical sill complexes consist of a saucer-like inner sill at the base with an arcuate inclined sheet connecting it to a gently inclined, commonly ragged, outer rim. Bilaterally symmetrical sill complexes are sourced by magma diverted from a magma conduit feeding an overlying volcano. With an elongate, concave upwards, trough-like geometry bilaterally symmetrical sills climb away from the magma source from which they originate. Both sill complex types can appear as isolated bodies but commonly occur in close proximity and consequently merge, producing hybrid sill complexes. Radial sill complexes consist of a series of radiating primary flow units. With dimensions up to 3 km, each primary flow unit rises from the inner saucer and is fed by primary magma tube. Primary flow units contain secondary flow units with dimensions up to 2 km, each being fed by a secondary magma tube branching from the primary magma tube. Secondary flow units in turn are composed of 100-m scale tertiary flow units. A similar branching hierarchy of flow units can also be seen in bilaterally symmetrical sill complexes, with their internal architecture resembling an enlarged version of a primary flow unit from a radial sill complex. This branching flow pattern, as well as the interaction between flow units of varying orders, provides new insights into the origin of the structures commonly seen within sill complexes and the hybrid sill bodies produced by their merger. The data demonstrate that each radially symmetrical sill complex is independently fed from a source located beneath the centre of the inner saucer, grows by climbing from the centre outwards and that peripheral dyking from the upper surface is a common feature. These features suggest a laccolith emplacement style involving peripheral fracturing and dyking during inner saucer growth and thickening. The branching hierarchy of flow units within bilaterally symmetrical sill complexes is broadly similar to that of primary flow units within a radially symmetrical sill complex, suggesting that the general features of the laccolith emplacement model also apply.

Aspergillus nidulans RhoA is involved in polar growth, branching, and cell wall synthesis

Growth of the filamentous fungus Aspergillus nidulans begins when the conidium breaks dormancy and grows isotropically. Eventually a germ tube emerges and the axis of growth remains fixed in the primary hypha while new growth axes are established basally to form secondary germ tubes and lateral branches. Rho1 is a Rho family GTPase that has been shown to be involved in polarity establishment and cell wall deposition in Saccharomyces cerevisiae. A gene predicted to encode a Rho1 homolog was cloned from A. nidulans and named rhoA. Strains carrying ectopic copies of the constitutively active rhoA G14V allele or the dominant rhoA E40I allele were created and characterized. The constitutively active rhoA G14V strain grew slowly relative to wild type and showed an abnormal clustered pattern of branch emergence. The rhoA G14V strain also labeled intensely with calcofluor, showed elevated levels of cell wall N-acetylglucosamine and had unusually thick cell walls. The dominant rhoA E40Istrain was accelerated in the emergence of secondary and tertiary germ tubes, and lateral branches relative to wild type and showed lysis with prolonged incubation. The rhoA E40I strain also was hypersensitive to the cell wall disrupting agents calcofluor and caspofungin acetate and showed an increase in cell wall N-acetylglucosamine levels. Our results suggest that rhoA plays a role in polarity, proper branching pattern, and cell wall deposition.

Transient displacement of a viscoplastic material by air in straight and suddenly constricted tubes

We examine the transient displacement of a viscoplastic material from straight or suddenly constricted cylindrical tubes of finite length. Our general goal is to develop accurate and efficient numerical methods for the fundamental study of processes in which a gas is displacing a liquid from prototype geometries under various operating conditions. Such processes can be part of the Gas Assisted Injection Molding (GAIM) or enhanced oil recovery. To this end, we use the mixed finite element method coupled with a quasi-elliptic mesh generation scheme in order to follow the very large deformations of the fluid volume. The displacing fluid is gas at high pressure, which forms a bubble of increasing length and a shape that depends on the fluid properties, the flow conditions, and the tube geometry. The cross-section of the bubble is always smaller than that of the tube due to adherence of fluid on the tube walls. The thickness of the remaining film depends on the same parameters and for most of its length it behaves as unyielded material. Unyielded material also arises in front of the bubble, around the axis of symmetry of the tube(s) and in the case of a constricted tube near the recirculation corner, but not around the entrance of the secondary tube. The rate of growth of the ‘tip splitting’ instability, that arises at relatively large values of the Reynolds number for Newtonian fluids in straight tubes, decreases as the Bingham number increases and, eventually, the instability disappears. The resistance provided by the constricted tube downstream makes the bubble move at a nearly constant velocity only when the Bingham number is not large. When the bubble approaches the constriction it becomes more pointed, but after entering it, the bubble reassumes its well-developed profile. Depending on parameter values, the bubble in the secondary tube may periodically split, thus forming a train of smaller bubbles directed towards the exit of the tube, a phenomenon for which experimental evidence exists.

HEAT TRANSFER FROM AN ELECTRONIC MODULE PLACED DOWNSTREAM OF A FENCE

The present work investigates experimentally the heat transfer and flow characteristics for an electronic module mounted on a simulated printed circuit board placed downstream of a fence on the bottom wall of a duct with an aspect ratio of 4. The module height (B) to channel height (H) ratio is fixed at B/H=0.317. Three different values for the fence height (b) and four values for the spacing between the fence and the module (S) were investigated in such a manner that the ratio b/B=1, 1.5 and 2, and the ratio S/B=1, 2, 3, and 4. Reynolds number, based on the streamwise length of the module (L), was ranged from 8000 to 40000. The results for the module without fence displayed some noticeable differences as compared to the smooth duct flow due to the existence of the separation-reattachment flow patterns. Secondary vortex tubes were existed at the module sides due to the presence of the fence and these vortices have significant effects on both the heat transfer and flow friction. Both Nusselt number and Fanning friction factor are strongly dependent on Reynolds number while they are critically dependent on both the fence height and spacing. A maximum Nusselt number enhancement ratio (Nu/NuN_F) of about 1.94 was obtained corresponding to a friction factor ratio (F/FN_F) of about 6.62 at the condition (Re=8700, b/B=1 .5 and S/B=2). It was found that the fence with b/B=1 provides the best performance based on the criterion of equal mass flow rate. New correlations were obtained for the average Nusselt number and the Fanning friction factor utilizing the present measurements within the investigated range of the different parameters.

Diameter-selective resonant Raman scattering in double-wall carbon nanotubes

Double-wall carbon nanotubes (DWNT's) have been studied by Raman scattering using different excitation wavelengths and their spectra compared to those of single wall nanotubes (SWNT's) and ${\mathrm{C}}_{60}$-SWNT peapods. Raman scattering from the radial and tangential vibrational modes of very small diameter $d\ensuremath{\sim}0.6--0.9 \mathrm{nm}$ secondary (interior) semiconducting tubes within the DWNT can be unambiguously identified with 647.1 and 1064 nm excitations. The frequency of the tangential displacement vibrational modes identified with these secondary (interior) tubes is found to be downshifted by $\ensuremath{\sim}7 {\mathrm{cm}}^{\ensuremath{-}1}$ relative to that of the larger primary (exterior) tubes that exhibit a diameter $d\ensuremath{\sim}1.3--1.6 \mathrm{nm}.$ This downshift strongly suggests that at small tube diameters (i.e., $d\ensuremath{\sim}0.7 \mathrm{nm}),$ the associated wall curvature of the nanotube may require an admixture of ${\mathrm{sp}}^{3}$ character in the C-C interaction. Our results also show that the value ${\ensuremath{\gamma}}_{0}=2.90 \mathrm{eV}$ for the nearest C-C tight binding integral is consistent with the resonant enhanced Raman scattering from DWNT's.

Nerve conduits for nerve reconstruction

Although autogenous nerve grafting remains the gold standard for repair of peripheral nerve defects, the use of various conduits can be a substitute provided these conduits meet the above-mentioned prerequisites. For the moment, autogenous vein grafts or denatured muscle grafts can be used to bridge short defects, especially in distal sensory nerves. Incorporation of muscle into a vein graft expands its application to longer defects in bigger nerves. PGA conduits have also been clinically proven to be reliable in reconstruction of digital nerve defects. Although nonabsorbable conduits cause irritation and nerve compression that necessitates secondary surgery removal, silicone tubes or Goretex tubes can be used in selected cases until absorbable conduits large enough for major peripheral nerves are available. To date, 3 cm seems to be the barrier for conduits. Incorporation of trophic factors and Schwann cells into the conduits will make their way into the clinic if problems like controlled release of trophic factors, obtaining and sustenance of an appropriate number of viable Schwann cells, are solved.

Aspergillus nidulans septin AspB plays pre- and postmitotic roles in septum, branch, and conidiophore development.

Members of the septin family of proteins act as organizational scaffolds in areas of cell division and new growth in a variety of organisms. Herein, we show that in the filamentous fungus Aspergillus nidulans, the septin AspB is important for cellular division, branching, and conidiation both pre- and postmitotically. AspB localizes postmitotically to the septation site with an underlying polarity that is evident as cytokinesis progresses. This localization at the septation site is dependent on actin and occurs before the cross-wall is visible. AspB localizes premitotically as a ring at sites of branching and secondary germ tube emergence. It is the only known branch site marker. In addition, AspB is found at several stages during the development of the asexual reproductive structure, the conidiophore. It localizes transiently to the vesicle/metula and metula/phialide interfaces, and persistently to the phialide/conidiospore interface. A temperature-sensitive mutant of AspB shows phenotypic abnormalities, including irregular septa, high numbers of branches, and immature asexual reproductive structures.

Bimodal breathing in jumping spiders: morphometric partitioning of the lungs and tracheae in Salticus scenicus (Arachnida, Araneae, Salticidae).

In jumping spiders, both the book lungs and the tracheal system are well-developed. The tracheal system consists of four thick primary tracheae that branch into small secondary tracheae, some of them ending in the opisthosoma and others entering the prosoma. We used stereological morphometric methods to investigate the morphological diffusing capacity of the lungs and of the walls of the secondary tracheae ('lateral diffusing capacity') of two groups of Salticus scenicus with mean body masses of 2.69 mg (group A) and 5.28 mg (group B). The thickness of the gas-exchange epithelium of the lungs was 0.164 microm (group A) and 0.186 microm (group B) for the total diffusion barrier. The secondary tracheae were divided arbitrarily into seven classes according to their inner diameter (1-7 microm). The diffusion barriers of the tracheal walls tend to be thinnest (0.17 and 0.18 microm) for the smallest tracheae, the walls of the other tracheal classes having approximately the same thickness of diffusion barrier (0.24-0.32 microm). The calculated oxygen-diffusing capacity (D(O(2))) for the lungs was 16.4 microl min(-1) g(-1) kPa(-1) for group A and 12 microl min(-1) g(-1) kPa(-1) for group B; the D(O(2)) of the walls of all secondary tracheae was 5.91 microl min(-1) g(-1) kPa(-1) for group A animals and 6.63 microl min(-1) g(-1) kPa(-1) for group B animals. Our results are consistent with the hypothesis that the tracheal system plays an important role in gas exchange in jumping spiders. Resting and low-activity oxygen consumption rates can be met by the lungs or the tracheae alone, while high oxygen demands can be met only if both respiratory systems are working together. Tracheae entering the prosoma have only 4-10 % of the total tracheal diffusing capacity, thus providing sufficient oxygen for the nervous system but not being able to prevent muscle fatigue. The similar thickness of the walls of all tracheal classes is consistent with the hypothesis that the secondary tube tracheae function as 'tracheal lungs', supplying the haemolymph and organs by lateral diffusion.

Ultrastructural evidence for nutritional exchange between brooding unionid mussels and their glochidia larvae

Abstract. The life history of unionid bivalve molluscs includes retention of developing embryos within the gills of parental mussels. This brooding behavior may facilitate nutrient transfer to the glochidia larvae, i.e., matrotrophy. To address this possibility, morphological relationships between brood chambers and developing larvae of Pyganodon cataracta and Utterbackia imbecillis were examined with TEM, and larval shells were observed with SEM, for features that could be associated with the uptake of dissolved materials. Early in brooding, glochidia are enclosed in a vitelline membrane that physically contacts numerous cilia and microvilli of the epithelial cells lining the brood chamber (marsupium). The vitelline membrane subsequently disappears. Lamellar tissues of parental mussels initially have large deposits of glycogen that diminish during the course of brooding. Septa separating brood chambers from adjacent secondary water tubes have numerous mitochondria and microvilli, suggesting the potential for active transport of materials into or out of the marsupia. Since punctae (pores) in the larval shells become filled with an organic matrix early in brooding, they are unlikely to be involved in nutrient exchange. Ultrastructure of the brood chamber and physical contact between the parental mussel and larvae are consistent with a nutritive role for retention of glochidia in the marsupia.