Thick Bridge Research Articles

Experimental conditions affecting the measured fracture toughness at the microscale: Notch geometry and crack extension measurement

Experimental fracture mechanics at the microscale became an indispensable tool for understanding and developing advanced material systems. In case of linear elastic fracture mechanics, stringent requirements are typically only warranted for very brittle materials. The material properties of semi-brittle materials might be accessible by elasto-plastic fracture mechanics. However, challenges exist in determining the crack length, in producing geometry and notch geometry, in defining of the initiation toughness and in extracting the size independent crack resistance curves. In this study, we assess current approaches of measuring the fracture toughness of semi-brittle materials by elasto-plastic fracture mechanics. We investigate the notch geometry (through thickness notch and bridge notch), the notch depth and the method of determining in situ the crack length for ultrafine grained tungsten. Further challenges due to the overlap of sample size and crack process zone are identified. Finally, we propose a workflow for analyzing the elasto-plastic fracture toughness of material systems at the microscale.

<p class="Body"><strong>Two new species of the feather mite genus <em>Pteroherpus</em> Gaud, 1981 (Analgoidea, Pteronyssidae) from China</strong></p>

Two new pteronyssid feather mite species are described from passeriform birds in China: Pteroherpus pomatorhinae sp. nov. from the Streak-breasted Scimitar-babbler Pomatorhinus ruficollis Hodgson (Passeriformes, Timaliidae), and Pteroherpus chinensis sp. nov. from the Collared Finchbill Spizixos semitorques Swinhoe (Passeriformes, Pycnonotidae). Pteroherpus pomatorhinae sp. nov. belongs to the diploplax species group. The males of Pteroherpus pomatorhinae sp. nov. have the prodorsal shield elongated, the opisthosoma narrowed to posterior end, the opisthosomal lobes slightly elongated, and two pairs of small additional sclerites (one dorsally, between prodorsal and hysteronotal shield, and one ventrally posterior to genital apparatus). The females of Pteroherpus pomatorhinae sp. nov. have a pair of anterior hysteronotal sclerites, a central sclerite, a pair of lateral opisthosomal sclerites partially split into lateral and inner fragments and a pair of pygidial sclerites. The central sclerite has almost parallel lateral margins and concave posterior margin, and the posterior ends of the fragments of opisthosomal shields are connected by a thick bridge. Pteroherpus chinensis sp. nov. belongs to the hoplophorus species group. The males of Pteroherpus chinensis sp. nov. have prodorsal shield slightly longer than wide, the opisthosoma moderately narrowed to posterior end, the opisthosomal lobes wide and short and the adanal shield with irregular form. The females of Pteroherpus chinensis sp. nov. have the anterior hysteronotal sclerite fused with the prodorsal shield into a complex shield, a central sclerite, a pair of lateral opisthosomal sclerites and a pair of pygidial sclerites. The central sclerite is well delimited, and shaped as a longitudinal plate, slightly narrower posteriorly, with slightly convex anterior margin, concave lateral margins, and strongly convex posterior end.

1685 Endoscopic Fistulectomy of an Obstructive Esophagogastric Mucosal Bridge

INTRODUCTION: Esophageal mucosal bridges are rare complications from many causes including congenital abnormalities, radiotherapy, sclerotherapy, nasoenteric feeding tubes, or Crohn’s disease. Mucosal bridges are made of smooth muscle crossing gastrointestinal lumen and resulting in a double barrel appearance on endoscopy. Pathogenesis may involve mucosal undermining by ulceration followed by healing, re-epithelialization of the mucosal undersurface, and formation of a mucosal tube attached to the non-ulcerated wall. Therefore, chronic, repetitive ulcerations and subsequent healing may lead to bridge formation. Another theory is that inflamed walls of esophagus contacting one another allows granulation tissue to form adhesions resulting in a mucosal bridge. This could explain fistula formation in inflammatory bowel disease. CASE DESCRIPTION/METHODS: A 68-year-old woman presented with a 6-year history of progressive solid food dysphagia and gastroesophageal reflux. Her past surgical history was significant for laparoscopic band surgery complicated by gastric band erosion into the stomach at the gastroesophageal junction that required subsequent gastric band removal and omental flap reinforcement of the gastric perforation nine years prior to presentation. A diagnostic upper endoscopy revealed an esophageal fistula at the gastroesophageal junction and biopsies at the junction showed chronic inflammation without dysplasia. The upper endoscope was advanced to the gastroesophageal junction at 37 cm from the entry site. Proximal to the gastroesophageal junction, two esophageal lumens were seen leading to the gastric lumen due to a thick mucosal bridge causing partial obstruction to the stomach. First, four hemostatic clips were placed at both ends of the stalk before mucosal incision to prevent bleeding. The bridge was grasped with forceps and fistulectomy was performed with a needle knife to incise the mucosal bridge between the clipped portion using electrocautery. On post-operative follow-up at week 6 and 12, the patient had complete resolution of dysphagia and no demonstrated recurrence of mucosal bridge formation. DISCUSSION: This is an unusual case of an esophagogastric fistula from a delayed adverse event of laparoscopic gastric band placement even after band removal and corrective surgery that caused dysphagia. It was successfully treated with endoscopic fistulectomy using hemostatic clips and a needle knife under direct visualization. This method has proven to be effective with no reported recurrences. Watch the video: http://bit.ly/2Y0JNws.

The Proximity and Josephson Effects in Niobium Nitride–Aluminum Bilayers

Highly disordered thin films of niobium nitride and the specific features of the proximity effect in NbN (S)–aluminum (N) bilayers with a large resistivity ratio, ρNbN/ρAl $$ \gg $$ 1, are studied. It is shown that magnetic screening and the critical current Ic of such SN structures significantly increase compared to the S layer. The observed effect is associated with the induced superconductivity in the N layer due to the proximity effect. The Josephson effect is demonstrated in NbN/Al–NbN–NbN/Al variable thickness bridges made of such SN bilayers.

Very Large Scale Integration of Josephson-Junction-Based Superconductor Random Access Memories

Arrays of vortex transitional (VT) memory cells with functional density up to 1 Mbit/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> have been designed, fabricated, and successfully demonstrated. This progress is due to recent advances in design optimization and in superconductor electronics fabrication achieved at MIT Lincoln Laboratory. As a starting point, we developed a demo array of VT cells for the 100-μA/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> MIT LL fabrication process SFQ5ee with eight niobium layers. The studied two-junction memory cell with a two-junction nondestructive readout occupied 168 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , resulting in an over 0.5 Mbit/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> functional density. Then, we reduced the cell area down to 99 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (corresponding to over 0.9 Mbit/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> functional density) by utilizing self-shunted Josephson junctions (JJs) with critical current density JC of 600 μA/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and eliminating shunt resistors. The fabricated high-JC memory cells were fully operational and possessed wide read/write current margins, quite close to the theoretically predicted values. We discuss approaches to further increasing the integration scale of superconductor memory and logic circuits: 1) miniaturization of superconducting transformers by using soft magnetic materials; and 2) reduction of JJ area by using planar high-JC junctions similar to variable thickness bridges.

Haemodynamic impacts of myocardial bridge length: A congenital heart disease

ObjectivesThere is an association between long and thick myocardial bridging (MB), haemodynamic perturbations and increased risk of myocardial infarction. This study aims to investigate the alteration in coronary haemodynamics with increasing the length of MB. MethodsAngiography and intravascular ultrasound were performed in 10 patients with varying length of MB in the left anterior descending (LAD) artery. In silico models of MB were developed based on the reconstructed three-dimensional model of the LAD. The entire LAD was divided into 3 segments, proximal (pre-bridge), bridge and distal (post-bridge). Transient computational fluid dynamics simulations were performed to derive distribution of blood residence time and wall shear stress (WSS) over entire vessel including proximal, bridge and distal segments. ResultsWith increasing the length of MB, a decreasing trend was observed in the WSS over proximal segment whereas an increasing trend was found in the WSS over bridge segment. When patients were divided into 2 groups based on the average length of MB in the whole cohort (Lave = 23.92 mm), patients with bridges longer than Lave had smaller WSS and higher residence time in the proximal segment compared to those with bridges shorter than Lave (0.59 ± 0.31 vs 0.21 ± 0.14 Pa and 0.0021 ± 0.0015 vs 0.0045 ± 0.0021 s). In contrast, patients with bridges longer than Lave had greater WSS in the bridge segment compared to those with bridges shorter than Lave (1.37 ± 1.66 vs 2.53 ± 3.14 Pa). No significant difference was found in the distal WSS of patients with short and long bridges. ConclusionOur findings revealed a direct relationship between the length of MB and haemodynamic perturbations in the proximal segment such that the increased length of MB is associated with decreased WSS and increased residence time.

Эффекты близости и Джозефсона в бислоях из нитрида ниобия и алюминия

The highly disordered thin films of niobium nitride and features of the manifestation of the proximity effect in the NbN (S) –Aluminium (N) bilayers with a high ratio of their specific resistances NbN / Al &gt;&gt; 1were investigated. It was shown that the magnetic screening and critical current Ic of such SN structures significantly increase compared with the S layer. The observed effect is associated with the appearance of induced superconductivity in the N layer due to the proximity effect. The Josephson effect was demonstrated in the variable thickness bridges NbN / Al - NbN - NbN / Al made from such SN bilayers.

Flow visualization of R32 in parallel-port microchannel tube

This paper presents visualization of two-phase flow of R32 in a parallel-flow microchannel tube with hydraulic diameter of 0.643 mm. Six visualization sections are installed in the facility, the same as in Li and Hrnjak (2017). Flow patterns are classified as: plug/slug, transitional, and annular flow. In plug/slug flow, a clear interface between liquid slug and vapor plug is observed. In transitional flow, the interface between slug and plug is broken and becomes a thick liquid ring and vapor bridge. In annular flow, only a liquid film is observed in the channel. The flow pattern map of R32 is reported. Mass flux changes from 50 to 300 kg-m−2s−1. The two-phase flow is generated by adding heat to subcooled refrigerant. The interface velocity and vapor plug length fraction (close to void fraction) are measured from high speed video. The velocity and vapor fraction agree to results based on a homogeneous assumption. When mass flux is 50 kg-m−2 s−1, the flow is always in plug/slug from vapor quality 0 to 1. Annular flow is observed at high quality when mass flux is higher than 100 kg-m−2 s−1. Transitional flow is observed when mass flux is higher than 150 kg-m−2 s−1, and it connects the plug/slug and annular flow patterns. Most flow pattern correlations fail to fit the measured flow pattern map. This is due to the difference in two-phase flow generation method and experimental conditions between this paper and the database used in correlations.

Heat Induced Changes of &lt;i&gt;Peda&lt;/i&gt; as Determined by Microstructure and Texture

Scanning Electron Microscopy (SEM) was used to study the relationship between submicroscopic structure and macroscopic properties occurred during processing of peda, a popular heat desiccated Indian dairy confection. Various components of milk undergo complex interaction amongst themselves due to prolonged heat treatment and with the added sugar molecules. An investigation was therefore carried out to study the sub-microstructure of peda to determine the internal structure and better understanding of the typical body &amp; texture of this traditional Indian sweet delicacy. The microstructure of peda reveals that the extensive heat treatment causes formation of casein-whey protein complexes which ultimately fused with lactose and sugar. The coalesced protein agglomerated as thick bridges. Large aggregates of lactose crystals and more void space was found in market peda which might be due to un-uniform kneading during processing. The textural properties differed markedly in laboratory and market peda. High hardness, fracturability, gumminess and chewiness and low springiness and cohesiveness of market peda might be due to extensive heating and lack of compactness. It was evident from SEM that the compactness of the network in market peda was lower as compared to laboratory samples and presence of scale or layer type structure in market samples indicated overheating of the product.Â

Effects of porosity and strain rate on the uniaxial compressive response of ice-templated sintered macroporous alumina

We investigated and thoroughly analyzed compressive response of ice-templated ceramics in quasistatic and dynamic regimes of strain rate. In the high pore volume regime, sintered scaffolds exhibited highly lamellar pore morphology and pore architecture transitioned to dendritic with the decreasing pore volume. Mechanical property measurements in the quasistatic regime of strain rate revealed that with increasing density, compressive response transitioned from a damageable, cellular-like failure to a brittle-like failure. We rationalized the measured results in terms of the propensity of the lamella walls to undergo buckling. Our conjecture is that in the high pore volume regime, lamella walls of the scaffolds are prone to buckling-induced elastic instability, which leads to a compressive response that manifests a gradual decrease of stress beyond peak stress. In contrast, we suggest that in the low pore volume regime thick lamella walls and extensive transverse bridging exhibit marked resistance to buckling-induced instability and scaffolds undergo a global failure, which is manifested in the measured quasistatic compressive response as a sharp drop of stress beyond peak stress. Dynamic compressive response of the scaffolds exhibited measurable differences relative to the quasistatic compressive response. Scaffolds exhibited a relatively gradual decrease of dynamic compressive stress beyond peak stress, and an overall improvement of compressive response and energy absorption capacity was measured under the dynamic loading conditions. We rationalized the measured differences in between the strain rate regimes in terms of the micro-inertia and other effects. This study is of critical significance for applications of ice-templated structures in dynamic environments.

Comparative Evaluation of Bioactive Materials and Their Nano-Counterpart as Pulp Capping Agents in Dogs’ Teeth

Introduction: Direct pulp-capping is an alternative procedure to extraction or endodontic therapy, in which a medicament is placed directly over the exposed pulp to maintain pulp vitality and facilitate the formation of protective barrier. Aim of study: The purpose of this study was to evaluate and compare the histological response of dog’s pulp after direct pulp capping with 3 different materials; MTA, Bioactive glass, CEM and their nanoparticles, at 1 month and 3 month time intervals. Materials & Methods: A total of 112 teeth in 8 dogs were used for this study, where 96 teeth were pulp capped with the investigated materials and 16 teeth were serving as negative control. The 14 teeth of each dog were classified into 6 experimental groups and one control (2 teeth each) as follows: Group A: was capped with MTA, Group B: was capped with NMTA, Group C: was capped with CEM, Group D: was capped with NCEM, Group E: was capped with Bioactive glass, Group F: was capped with Nano Bioactive glass and Group G: unprepared tooth (negative control). Dogs were randomly divided into 2 groups (4 dogs each), relative to the observation periods tested, 1 month and 3 months for histomorphological evaluation of pulp response after direct pulp capping with tested materials. Results: Regarding the dentin bridge formation, both NMTA and NCEM groups induced thick dentin bridge with irregular dentin pattern in 1 and 3 months evaluation time period while MTA and CEM induced thinner dentin bridge with regular dentin pattern. BG and NBG groups showed the lowest mean dentin bridge thickness values with no tubular dentin pattern. About the inflammatory reaction of the dental pulp to materials with conventional particle size; MTA displayed the highest prevalence of no inflammation followed by CEM while BG showed the highest prevalence of moderate inflammation and the highest inflammatory cell counts. All nanomaterials showed the highest mean inflammatory cell counts at both evaluations time periods. Conclusion: MTA and CEM can be considered favorable materials for direct pulp capping, while BG and NBG produced the worst inflammatory cell reaction, dentin bridge thickness and quality. Nanoparticles although increased dentin bridge thickness, they also increased the inflammatory cell reaction.

Quantitative assessment of liver fibrosis reveals a nonlinear association with fibrosis stage in nonalcoholic fatty liver disease.

Accurate staging of liver fibrosis is crucial to guide therapeutic decisions for patients with nonalcoholic fatty liver disease (NAFLD). Digital image analysis has emerged as a promising tool for quantitative assessment of fibrosis in chronic liver diseases. We sought to determine the relationship of histologic fibrosis stage with fiber amounts quantified in liver biopsy specimens for the better understanding of NAFLD progression. We measured area ratios of collagen and elastin fibers in Elastica van Gieson‐stained biopsy tissues from 289 patients with NAFLD from four hospitals using an automated computational method and examined their correlations with Brunt's fibrosis stage. As a secondary analysis, we performed multivariable logistic regression analysis to assess the associations of the combined area ratios of collagen and elastin with noninvasive fibrosis markers. The combined fiber area ratios correlated strongly with Brunt's stage (Spearman correlation coefficient, 0.78; P < 0.0001), but this relationship was nonlinear (P = 0.007) with striking differences between stage 4 (median area ratios, 12.3%) and stages 0‐3 (2.1%, 2.8%, 4.3%, and 4.8%, respectively). Elastin accumulation was common in areas of thick bridging fibrosis and thickened venous walls but not in areas of perisinusoidal fibrosis. The highest tertile of the combined fiber area ratios was associated with the fibrosis‐4 index and serum type IV collagen 7s domain (7s collagen) levels, whereas the upper two tertiles of the fiber amounts significantly associated with body mass index, aspartate aminotransferase, and 7s collagen in the multivariable analysis. Conclusion: Quantitative fibrosis assessment reveals a nonlinear relationship between fibrosis stage and fiber amount, with a marked difference between stage 4 and stage 3 and much smaller differences among stages 0‐3, suggesting a heterogeneity in disease severity within NAFLD‐related cirrhosis. (Hepatology Communications 2018;2:58–68)

Special heavy plates and steel solutions for bridge building

In many European countries infrastructure, -road as well as railway infrastructure-, needs intensive investments to follow the growing demands of mobility and goods traffic. Steel or steel composite bridges offer in this context viable and very sustainable solutions. Due to its unlimited recyclability steel can in general be seen as the ideal material for such sustainable constructions, but especially when designers or fabricators exploit the nowadays available possibilities of steel industry very cost-efficient and remarkable constructions are realizable. This paper will highlight some of these newest developments in heavy plates for bridge building. For example, for small span railway bridges the so-called thick plate trough bridges have proven to be a favourable concept. Very heavy plates with single plate weights up to 42 t allow building these bridges very efficiently out of one or very few single plates. Another interesting development is the so-called longitudinally profiled plates which allow a varying plate thickness along the actual loading profile. As last point the rising entry of higher strength steels in bridge building will be discussed and it will be shown why thermomechanically rolled plates are the ideal solution for these demands.

Effect on Stresses of Structural Details of Orthotropic Steel Deck with Thin Surfacing

Although it has the advantage of decreasing the loads on bridge deck when adopting thin surfacing, it is worse for the stress dispersion of vehicle loads, as a result, it is easy to generate local stress concentration of structural details of orthotropic steel deck. To study the stresses of orthotropic steel bridge decks, especially for the structural weld details, which is significant for fatigue durability evaluation. Partial models are created by finite element analyses to analyze the stresses of both normal thickness bridge pavement and thin surfacing under different load locations, and the kinds of material of pavement and the thickness of bridge deck are also considered in the calculations. It’s found that stress amplitude of objective fatigue details of TPO pavement increase up to 28.4% when the models share the same structure dimension, and the thickness of TPO pavement has little impact on the stress amplitude of objective fatigue details which could be ignored, while the influence of the thickness of the TPO pavement is considerable. And the increase of the thickness of bridge deck helps decrease the stress amplitude of objective fatigue details.

Predicting the stiffness of shear diaphragm panels composed of bridge metal deck forms

The behavior of building industry metal sheeting under shear forces has been extensively studied and equations have been developed to predict its shear stiffness. Building design engineers can make use of these equations to design a metal deck form bracing system. Bridge metal deck forms differ from building industry forms by both shape and connection detail. These two factors have implications for using these equations to predict the shear stiffness of deck form systems used in the bridge industry. The conventional eccentric connection of bridge metal deck forms reduces their shear stiffness dramatically. However, recent studies have shown that a simple modification to the connection detail can significantly increase the shear stiffness of bridge metal deck form panels. To the best of the author's knowledge currently there is not a design aid that can be used by bridge engineers to estimate the stiffness of bridge metal deck forms. Therefore, bridge engineers rely on previous test results to predict the stiffness of bridge metal deck forms in bracing applications. In an effort to provide a design aid for bridge design engineers to rely on bridge metal deck forms as a bracing source during construction, cantilever shear frame test results of bridge metal deck forms with and without edge stiffened panels have been compared with the SDI Diaphragm Design Manual and ECCS Diaphragm Stressed Skin Design Manual stiffness expressions used for building industry deck forms. The bridge metal deck form systems utilized in the tests consisted of sheets with thicknesses of 0.75 mm to 1.90 mm, heights of 50 mm to 75 mm and lengths of up to 2.7 m; which are representative of bridge metal deck forms frequently employed in steel bridge constructions. The results indicate that expressions provided in these manuals to predict the shear stiffness of building metal deck form panels can be used to estimate the shear stiffness of bridge metal deck form bracing systems with certain limitations. The SDI Diaphragm Design Manual expressions result in reasonable estimates for sheet thicknesses of 0.75 mm, 0.91 mm, and 1.21 mm and underestimate the shear stiffness of 1.52 and 1.90 mm thick bridge metal deck forms. Whereas, the ECCS Diaphragm Stressed Skin Design Manual expressions significantly underestimate the shear stiffness of bridge metal deck form systems for above mentioned deck thicknesses.

Active region fine structure observed at 0.08 arcsec resolution

The various mechanisms of magneto-convective energy transport determines the structure of sunspots and active regions. We characterise the appearance of light bridges and other fine-structure details and elaborate on their magneto-convective nature. We present speckle-reconstructed images taken with the broad-band imager at the 1.5 m GREGOR telescope in the 486nm and 589nm bands. We estimate the spatial resolution from the noise characteristics of the image bursts and obtain 0.08" at 589nm. We describe structure details in individual best images as well as the temporal evolution of selected features. We find branched dark lanes extending along thin (~1") light bridges in sunspots at various heliocentric angles. In thick (~2") light bridges the branches are disconnected from the central lane and have a Y shape with a bright grain toward the umbra. The images reveal that light bridges exist on varying intensity levels and that their small-scale features evolve on timescales of minutes. Faint light bridges show dark lanes outlined by the surrounding bright features. Dark lanes are very common and are also found in the boundary of pores. They have a characteristic width of 0.1" or smaller. Intergranular dark lanes of that width are seen in active region granulation. While central dark lanes in thin light bridges are elevated and associated with an density increase above upflows, the dark lane branches correspond to locations of downflows and are depressed relative to the adjacent bright plasma. Thick light bridges with central dark lanes show no projection effect. They have a flat elevated plateau that falls off steeply at the umbral boundary. There, Y-shaped filaments form as they do in the inner penumbra. This indicates the presence of inclined magnetic fields, meaning that the umbral magnetic field is wrapped around the convective light bridge.

A New Morphological Type of Volvox from Japanese Large Lakes and Recent Divergence of this Type and V. ferrisii in Two Different Freshwater Habitats.

Volvox sect. Volvox is characterized by having unique morphological characteristics, such as thick cytoplasmic bridges between adult somatic cells in the spheroids and spiny zygote walls. Species of this section are found from various freshwater habitats. Recently, three species of Volvox sect. Volvox originating from rice paddies and a marsh were studied taxonomically based on molecular and morphological data of cultured materials. However, taxonomic studies have not been performed on cultured materials of this section originating from large lake water bodies. We studied a new morphological type of Volvox sect. Volvox (“Volvox sp. Sagami”), using cultured materials originating from two large lakes and a pond in Japan. Volvox sp. Sagami produced monoecious sexual spheroids and may represent a new morphological species; it could be clearly distinguished from all previously described monoecious species of Volvox sect. Volvox by its small number of eggs or zygotes (5–25) in sexual spheroids, with short acute spines (up to 3 μm long) on the zygote walls and elongated anterior somatic cells in asexual spheroids. Based on sequences of internal transcribed spacer (ITS) regions of nuclear ribosomal DNA (rDNA; ITS-1, 5.8S rDNA and ITS-2) and plastid genes, however, the Volvox sp. Sagami lineage and its sister lineage (the monoecious species V. ferrisii) showed very small genetic differences, which correspond to the variation within a single biological species in other volvocalean algae. Since V. ferrisii was different from Volvox sp. Sagami, by having approximately 100–200 zygotes in the sexual spheroids and long spines (6–8.5 μm long) on the zygote walls, as well as growing in Japanese rice paddies, these two morphologically distinct lineages might have diverged rapidly in the two different freshwater habitats. In addition, the swimming velocity during phototaxis of Volvox sp. Sagami spheroids originating from large lakes was significantly higher than that of V. ferrisii originating from rice paddies, suggesting adaptation of Volvox sp. Sagami to large water bodies.

Condensation heat transfer enhancement mechanism for vertical upflows by the phase separation concept at small gravity

In the field of aerospace, minimum and seal of equipments cause the increase in the thermal loading sharply. Due to the lack of driving force, the performance of conventional condenser deteriorates greatly under the small gravity environment, which leads to reduction in the service life of equipments. In this study, a passive condenser, developed on basis of the phase separation concept, is utilized to improve the performance of the condensation heat transfer under the small gravity environment. As a result of the limitation of experiments, the mechanisms of heat transfer enhancement of the phase separation condenser tube are revealed through numerical simulation based on the volume-of-fluid (VOF) method. The following conclusions could be obtained: (1) A novel phase distribution of ‘‘gas near the tube wall and liquid in the tube core’’ is formed. The thin liquid film is indeed created after the flow pattern modulation by inserting mesh cylinder. (2) The condensation quantity for single bubble in the annular region increases about 16 times greater than that in the bare tube region in the case of Jl = 0.0574m/s and Jg = 0.0229m/s. (3) Gas volume fraction affects the parameters of liquid film thickness, bubble length and liquid bridge length. The increase in the gas volume fraction results in the decrease in the evaluation index from 21.56 to 12.82. The evaluation index is defined as the ratio of the condensation quantities per unit tube length of the annular region and the bare tube region.

Steel fiber as replacement of minimum shear reinforcement for one-way thick bridge slab

This paper evaluates the possibility of replacing minimum shear reinforcement by steel fibers in both prestressed and non-prestressed thick concrete slab. Due to brittle behavior of plain concrete in tension, shear failure of thick slab is generally catastrophic. The use of minimum shear reinforcement is recommended in many instances to avoid such failure. This paper presents an alternative solution realising that the use of optimum steel fibers can give ductility performance equivalent to the slab with minimum shear reinforcement. To evaluate the effect of steel fibers on shear performance, eight full-scale tests are carried out. The influence of fibers on shear performance is evaluated and its potential to replace the minimum transverse steel of thick slab is discussed. Finally a procedure for predicting the shear capacity of such slab is presented.

Subtotal lower lid reconstruction from upper eyelid full thickness bridge flap with earlier 2(nd) stage surgery at 3 weeks.

Subtotal lower lid reconstruction from upper eyelid full thickness bridge flap with earlier 2(nd) stage surgery at 3 weeks.