Large Number Of Filaments Research Articles

HYDROBIOLOGICAL INDICATORS OF ACTIVATED SLUDGE OF INDUSTRIAL WASTEWATER TREATMENT PLANT

The hydrochemical and hydrobiological indicators of activated sludge of industrial wastewater treatment plant of nitrogen-fertilizers enterprise were characterized. Nitrified activated sludge consists of loose flocs with a large number of filaments (156–495 ind./cm3), which determines its low sedimentation properties (sludge index 260–367 cm3/g). Its microfauna is characterized by low species diversity, with the dominance of the shell amoebae Euglypha. Denitrification sludge is formed from flakes 0.27–0.76 mm2 in size with a large number of dispersed bacteria due to the absence of microfauna under anaerobic conditions. In aeration tanks, intensive aeration and low concentration of wastewater ensure the development of flocculeforming bacteria Zoogloea ramigera, stalked ciliates and rotifers. The activated sludge of aeration tanks consists of compact large floccules 0.64–1.28 mm2 in size with an optimal amount of filamentous bacteria (1009–10 083 ind/cm3).

Persistent homology of the cosmic web – I. Hierarchical topology in ΛCDM cosmologies

ABSTRACT Using a set of Lambda cold dark matter simulations of cosmic structure formation, we study the evolving connectivity and changing topological structure of the cosmic web using state-of-the-art tools of multiscale topological data analysis (TDA). We follow the development of the cosmic web topology in terms of the evolution of Betti number curves and feature persistence diagrams of the three (topological) classes of structural features: matter concentrations, filaments and tunnels, and voids. The Betti curves specify the prominence of features as a function of density level, and their evolution with cosmic epoch reflects the changing network connections between these structural features. The persistence diagrams quantify the longevity and stability of topological features. In this study, we establish, for the first time, the link between persistence diagrams, the features they show, and the gravitationally driven cosmic structure formation process. By following the diagrams’ development over cosmic time, the link between the multiscale topology of the cosmic web and the hierarchical buildup of cosmic structure is established. The sharp apexes in the diagrams are intimately related to key transitions in the structure formation process. The apex in the matter concentration diagrams coincides with the density level at which, typically, they detach from the Hubble expansion and begin to collapse. At that level many individual islands merge to form the network of the cosmic web and a large number of filaments and tunnels emerge to establish its connecting bridges. The location trends of the apex possess a self-similar character that can be related to the cosmic web’s hierarchical buildup. We find that persistence diagrams provide a significantly higher and more profound level of information on the structure formation process than more global summary statistics like Euler characteristic or Betti numbers.

Experimental and Numerical Investigations on the Mechanical Characteristics of Carbon Fiber Sensors.

Carbon fiber-based materials possess excellent mechanical properties and show linear piezoresistive behavior, which make them good candidate materials for strain measurements. They have the potential to be used as sensors for various applications such as damage detection, stress analysis and monitoring of manufacturing processes and quality. In this paper, carbon fiber sensors are prepared to perform reliable strain measurements. Both experimental and computational studies were carried out on commercially available carbon fibers in order to understand the response of the carbon fiber sensors due to changes in the axial strain. Effects of parameters such as diameter, length, and epoxy-hardener ratio are discussed. The developed numerical model was calibrated using laboratory-based experimental data. The results of the current study show that sensors with shorter lengths have relatively better sensitivity. This is due to the fact short fibers have low initial resistance, which will increase the change of resistance over initial resistance. Carbon fibers with low number of filaments exhibit linear behavior while nonlinear behavior due to transverse resistance is significant in fibers with large number of filaments. This study will allow researchers to predict the behavior of the carbon fiber sensor in real life and it will serve as a basis for designing carbon fiber sensors to be used in different applications.

Effect of the texture of Langmuir copolymer films on structural phase transitions

An atomic-force microscopy study has surprisingly revealed that ultrathin copolymer films fabricated according to Langmuir technology constitute a network of tangled filaments. A long-range order is absent in the samples. The observed filaments consist of several parallel-packed copolymer chains. The shape of ferroelectric domains in a film is independent of the direction of copolymer chains. Each domain includes a large number of filaments. The nature of high-temperature (ferroelectric) and low-temperature phase transitions has been discussed in terms of structural data.

Computational Fluid Dynamics Simulations of the Complex Geometry of a Technical Textile

The use of virtual prototypes for the prediction of relevant flow related parameters is well established in many industries such as the automotive industry. For the development of technical textiles an analogous approach is anticipated as being beneficial. However, so far the complex geometry of textiles consisting of a very large number of filaments has impeded this approach. We utilize this approach for the first time investigating a fabric, which is used during the paper forming process. The most challenging aspect for the simulation is the the process of geometry creation by use of single filaments together with the indispensable simplifications for a currently marketed fabric. Meshes of different sizes up 20 million cells have been generated and results from CFD calculations will be displayed together with an analysis of the numerical accuracy. The individual relevance of the simulation experiments will be discussed. Physical experiments at ambient temperature of laminar water flow through the same fabric under comparable conditions with a Reynolds Number of 15 based on pipe diameter of 9.0 mm and pipe volume flow rate averaged velocity magnitude of 0.00172 m/s were performed. The Reynolds Number based on the diameter of the different filaments of 0.2 mm up to 0.45 mm is approx. between 0.34 and 0.77. The experimental set up using Magnetic Resonance Imaging (MRI) will be explained. The use of this experimental approach as a means to validate the results of the simulation will be critically evaluated.

Effect of number of filaments on the critical current density in multifilamentary Bi-2223 tape

The critical current property of Bi2Sr2Ca2Cu3Ox(Bi-2223) silver-sheathed tape has been remarkably improved by application of ConTrolled Over Pressure (CT-OP) process with adjusting temperature and oxygen partial pressure. For further improvement of the property of Bi-2223 tapes, the effect of number of filaments on the critical current density Jc was investigated. It was found that Jc was higher and its decrease with increasing magnetic field was weaker in the tape with larger number of filaments. In addition, the irreversibility field Bi increased with increasing filament number. The field-angle anisotropy Jc(0°)/Jc(90°) of the tape with the largest filament number was smallest, where the field-angle was measured from the a–b plane. However, the out-of-plane misorientation angle is fairly small in this tape. Hence, the low field-angle anisotropy in this tape seems to be attributed to improved superconductivity in the block layers in the superconducting region near the interface with silver matrix.

Superplastic deformation behavior of hot-rolled AZ31 magnesium alloy sheet at elevated temperatures

Uniaxial tensile tests were carried out in the temperature range of 250–450°C and the strain rate range of 0.7×10−3–1.4×10−1 s−1 to evaluate the superplasticity of AZ31 Mg alloy. The threshold stress which characterizes the difficulty for grain boundary sliding was calculated at various temperatures. The surface relieves of superplastically deformed specimens were observed by using a scanning electronic microscope (SEM). Results show that, at the temperature of 400°C and strain rate of 0.7×10−3s−1, the strain rate sensitivity exponent, i e, m value reaches 0.47 and the maximum elongation of 362.5% is achieved. Grain boundary sliding (GBS) is the primary deformation mechanism and characterized by a pronounced improvement in the homogeneity with increasing temperatures. A large number of filaments were formed at the end of deformation and integranular cavities were produced with the necking and fracture of filaments. Finally, the model for the formation of intergranular cavities was proposed.

Analysis of room-temperature results on normally conducting and superconducting channels through polymer films

There are strong reasons from dc and pulsed-current measurements, and from thermal conductivity results, for thinking that narrow channels through films of oxidized atatic polypropylene are superconducting at room temperature. It is thought that the conducting channels, with diameters less than or of the order of a micrometre, are composed of smaller nanofilaments, with diameters of the order of a nanometre. In the present paper a possible explanation is given of measurements which show that the average resistance of non-superconducting channels through films increases with film thickness more slowly than linearly. This result is interpreted in terms of how the Bose condensation temperatures of bosons in arrays of nanofilaments depend on the length and numbers of filaments, and examples are given of parameters of the arrays which could explain the data. The dispersion for the bosons is assumed to consist of a sum of linear and quadratic terms, which is an approximate type of dispersion reported for Cooper pairs. In order to fit the data with the model used, it is necessary to suppose that values of superconducting T c for channels composed of large numbers of filaments are only slightly above room temperature. It is argued that the larger T cs reported in 1989 when currents of 0.5 A were passed through channels may arise because (a) currents concentrate in a subchannel of smaller width than the original channel, and (b) current–current interactions draw the filaments of the subchannel sufficiently close together to increase the transverse bandwidth and T c in the model by the required amount.

Intercluster filaments of galaxies programme: abundance and distribution of filaments in the 2dFGRS catalogue

Filaments of galaxies are known to stretch between galaxy clusters at all redshifts in a complex manner. In this Letter, we present an analysis of the frequency and distribution of intercluster galaxy filaments selected from the 2dF Galaxy Redshift Survey. Out of 805 cluster–cluster pairs, we find at least 40 per cent have bona fide filaments. We introduce a filament classification scheme and divide the filaments into several types according to their visual morphology: straight (lying on the cluster–cluster axis; 37 per cent), warped or curved (lying off the cluster–cluster axis; 33 per cent), sheets (planar configurations of galaxies; 3 per cent), uniform (1 per cent) and irregular (26 per cent). We find that straight filaments are more likely to reside between close cluster pairs and they become more curved with increasing cluster separation. This curving is toward a larger mass concentration in general. We also show that the more massive a cluster is, the more likely it is to have a larger number of filaments. Our results are found to be consistent with a Λ cold dark matter cosmology.

Impacts of structural characteristics on activated sludge floc stability

Activated sludge samples from seven full-scale plants were investigated in order to determine the relationship between floc structure and floc stability. Floc stability was determined by shear sensitivity and floc strength. Floc structure was considered in terms of two size scales, the micro- and macrostructure. The microstructure refers to the organization of the floc components, such as the individual microorganisms. The macrostructure refers to the overall floc. The floc macrostructure was characterized by filament index, sludge volume index, size, and fractal dimension. It had a significant impact on floc stability. Large and open flocs with low fractal dimensions containing large number of filaments were more shear sensitive and had lower floc strength compared to small and dense flocs. Fluorescent in situ hybridization analysis indicated that the organization of the bacterial cells might also have an effect on the floc stability.

Synthesis and characterization of carbon filaments grown from Pd3P colloids

Amorphous carbon filaments were synthesized by catalytic pyrolysis of propene over Pd3P colloids. The channel close to the center of the filaments usually contained particles, which were analyzed by analytical electron microscopy to be palladium. The palladium particles could be found anywhere along the filament. The carbon filaments were of two types and of different diameters, about 8–15 nm and about 40–80 nm. The thinner type of filament shows a channel diameter of about 5 nm. The type of filament produced depends on the reaction conditions. Increased reaction time results in a large number of filaments, whereas an increased propene gas flow results in more of the thicker type of filaments.

Guiding large-scale spark discharges with ultrashort pulse laser filaments

Using the nonlinear propagation properties of ultrashort laser pulses in air, we were able to produce long ionized filaments that served to guide spark discharges. With a laser pulse energy of 20 mJ, one or two ionized filaments were created and could guide streamer discharges over 2 m air gaps, where the electric field was fairly uniform and had an average value of 0.6 MV/m. Such a guiding effect was observed for times of 1–3 μs after the laser pulse created the ionized filaments. Longer delays (10–15 μs) were recorded at higher laser pulse energy, with a larger number of filaments. Images of the early stages of the discharge of a uniform air gap show that the laser-produced ionized filaments do not initiate the discharge process but act rather as preferred channels where the leader growth is accelerated. In the end, these straight conductive channels carry the arc current as the voltage in the gap breaks down.

A new method to substantially reduce the processing time of Ag/Bi-2223 tapes

Multi-stage thermal cycling is commonly used in the processing of Ag/Bi-2223 tapes requiring a total annealing time often in excess of 100 h, which is very undesirable for large-scale production. A new process was investigated that reduced the heat treatment time for Ag/Bi-2223 tapes. In this process, the tape was quenched at the end of the 1st thermal cycle. Following either pressing or rolling, it was rapidly heated to the sintering temperature. In doing so, the usual decomposition and recovery of Bi-2223 during cooling and heating was eliminated, along with a reduced formation time for Bi-2223. By using this new procedure, the zero-field J c and the Bi-2223 volume fraction in tapes sintered for a total time of 20–30 h were comparable to those treated for 100 h using a conventional process. The results further confirm that a low-temperature annealing at 825°C in the end of the last thermal cycle eliminates residual 2201, hence improving J c. It was also found out that tapes containing a large number of filaments had a higher Bi-2223 volume fraction and exhibited a better J c vs. H performance, than for tapes with a small number of filaments, when both were processed for the same time period.

TEM specimen preparation and characterization of ceramic coatings on fiber tows

A method for making transmission electron microscopy (TEM) specimens of ceramic fibers is described. The specimens are particularly well suited for observation of ceramic coatings on a large number of filaments. The technique is also useful for preparation of extremely flat SEM specimens with good edge retention.

Effects of initial cold work conditions on the deformation and current capacity of monofilamentary and multifilamentary Bi-2223 conductors

The influences of initial cold work conditions on the deformation characteristics and the current-carrying capability of Bi-2223 powder-in-tube conductors have been investigated by varying the working friction and the amount of reduction per pass. The results demonstrate that deformation of the conductors can be very inhomogeneous depending on the working parameters. Specifically, dead zones are found within the transverse cross-sections of the tapes close to the tools - sample interfaces such that the bulk of the deformation is restricted to the central portions of the conductors. Since the core of monofilamentary tape is located outside the dead zones, it is highly densified when deformed under high friction condition resulting in the largest . On the other hand, a large number of filaments in multifilamentary tape reside within the dead zones such that high working friction does not result in optimum . Instead, a combination of low friction and large reduction per pass resulted in the most homogeneous deformation and highest current capacity.

Relation of strength distribution of Nb 3Al filaments to strength of multifilamentary superconducting composite wire

The distribution of tensile strength of Nb 3Al filaments and its relation to tensile strength of Nb 3Al multifilamentary superconducting composite wire were studied. The main results can be summarized-as follows: (1) The tensile strength of the extracted filaments with an average diameter of 24 μm was estimated based on the two-parameter Weibull distribution function. The shape and scale parameters were 7.0 and 530 MPa (for a standard length of 1 m), respectively. (2) Although the scatter of the strength of the Nb 3Al filaments was large, that of the multifilamentary composite was very small. This means that, when a large number of filaments are embedded in a composite, the stress leading to overall fracture of the composite is not very different from sample to sample, even though the strengths of the embedded filaments are significantly different. This feature was confirmed by means of a computer-aided Monte Carlo simulation. (3) It was shown by experiment and simulation that the strength of the Nb 3Al composite wire has a very slight dependence on length, although the strength of the Nb 3Al filament decreases markedly with increasing length. This result indicates that, even if the length of the composite wire is extended from a short, laboratory scale sample to an industrial scale, the reduction in strength will be very small.

Characterization of horse plasma gelsolin

Gelsolin can be purified from horse blood plasma by treating the plasma sequentially with an anion-exchange medium in the presence and then the absence of free Ca2+. The purified gelsolin migrates as a 90-kilodalton protein on electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate. It has an absorption coefficient of 1.4 mL/(mg.cm) and is similar in amino acid composition to other plasma gelsolins. Horse plasma gelsolin has an intrinsic sedimentation coefficient of 4.8S and a Stokes' radius of 3.8 nm. Hydrodynamic calculations suggest it to be a rather globular protein of 75,000 relative mass, a value similar to those calculated for human and pig plasma gelsolins from their amino acid sequences. Horse plasma gelsolin is able to nucleate actin polymerization, i.e., to abolish the lag observed between the initiation of polymerization of monomeric actin by the addition of salts and the rapid elongation phase of actin filament growth. This nucleation activity also results in lower final viscosities of F-actin solutions, as the existence of a larger number of filaments in samples that contain gelsolin requires that their average length be shorter.

Ultrastructural survey of the spinal cord of young tuatara (Sphenodon punctatus) with emphasis on the glia

Abstract The caudal spinal cord of three 3-month old Sphenodon were examined by light and electron microscopy. The normal spinal cord shows white matter being invaded by dark cells of a seemingly oligodendrocyte type, which appear to be forming myelin sheaths. The presence of large numbers of filaments (7–10 nm in diameter) between the standard organelles, including microtubules of 20–24 nm diameter, is unusual for oligodendrocytes, but quite typical for astrocytes. A single oligodendrocyte-like cell can envelope many axons in order to delimit specific areas of white matter. In 3-month old tuatara it is difficult to discriminate between oligodendrocytes, astrocytes, and various neural elements in the dorsal region of the spinal cord because they are still insufficiently differentiated. Motoneurons, however, are well developed. Ependymal cells resemble oligodendrocyte-like cells, but have retained an epithelial position with desmosomes in order to delimit the central canal. These cells possess intermediate...

Visualization and Identification of Cytoskeletal Filaments in Embryonic Chick Heart by the Quick-Freeze Deep-Etch Method Combined with Immunocytochemistry

Cytoskeletal filaments in myocardial cells of chick embryo (stage 18-20, day 3) were studied by immunocytochemical and rapid-freeze deep-etch methods. A three-dimensional network of cytoplasmic filaments surrounding nascent myofibrils was visualized in saponin-treated myocardial cells. The major part of the network was composed of 12 to 14 nm filaments in platinum replicas. To identify the filaments, the myocardial cells were permeabilized with Triton X-100 and treated with myosin subfragment-1 (S1) for actin or immunogold-labeled antibody for desmin. A large number of filaments in myofibrils and a few cytoplasmic filaments were decorated with S1. A loose network surrounding the myofibrils was not decorated with S1 but with gold particles. This finding means that the majority of filaments occupying the interfibrillar space were desmin-containing filaments.

Epithelial-Mesenchymal Junctional Area in an Early Stage of Odontogenesis in Macaca Fuscata

The epithelial-mesenchymal junctional area in tooth germs of one- and three-year-old Japanese monkeys was studied with electron microscopy.The plasma membranes at the distal ends of inner enamel epithelium cells were relatively even, and were associated with basement membrane. A large number of filaments, which were 15 nm in diameter and up to 2 μm in length, were present, extending perpendicularly from the basement membrane toward the dental papilla, forming an unique fibrillar layer. The distal cytoplasm of the cell contained rather few vesicles and granules which were positive for the acid phosphatase reaction. The distal ends of differentiating ameloblasts showed irregular undulations and numerous small processes which penetrated through the basement membrane and fibrillar layer. Following an increase of the undulations, the fibrillar layer and the basement membrane were engulfed by the cells and removed from the surface of pre-dentin. Large irregular bodies, which were filled with the filaments of the disintegrating fibrillar layer, were observed frequently. The distal cytoplasm contained a large number of coated pits, coated vesicles, and acid-phosphatase-positive granules. The fibrillar layer then disappeared, being replaced by collagen fibrils in the pre-dentin, which was in the stage of early mineralization.These results indicate that the fibrillar layer is removed by the differentiating ameloblasts and degraded through an engulfing system which is formed by the cell surfaces.