Continuous Streaks Research Articles

Ash-Decorated and Ash-Painted Soot from Residual and Distillate-Fuel Combustion in Four Marine Engines and One Aviation Engine.

Soot is typically the dominant component of the nonvolatile particles emitted from internal combustion engines. Although soot is primarily composed of carbon, its chemistry, toxicity, and oxidation rates may be strongly influenced by internally mixed inorganic metal compounds (ash). Here, we describe the detailed microstructure of ash internally mixed with soot from four marine engines and one aviation engine. The engines were operated on different fuels and lubrication oils; the fuels included four residual fuels and five distillate fuels such as diesel, natural gas, and Jet A-1. Using annular-dark-field scanning transmission electron microscopy (ADF-STEM), we observed that ash may occur either as distinct nodules on the soot particle (decorated) or as continuous streaks (painted). Both structures may exist within a single particle. Decorated soot was observed for both distillate and residual fuels and contained elements associated with either the fuel (V, Ni, Fe, S) or with the lubrication oil (Zn, Ca, P). Painted soot was observed only for residual-fuel soot, and only contained elements associated with the fuel. Additional composition measurements by inductively coupled plasma mass spectrometry (ICP-MS) of filter samples indicated that the internal mixing trends of ash with soot were consistent with the overall ash-to-carbon ratio of the sampled combustion aerosols. Painted soot may form when molten ash coagulates with or condenses onto soot within engines.

Isolation and identification of Saccharomyces cerevisiae for fermentation of rice polishing in Livestock feeding

Biomass of Saccharomyces cerevisiae wasenhancedin rice polishing by fermentation to increase protein contents of feedfor its use in livestock. Broth culture of Saccharomyces cerevisiae (2.6×108CFU/mL) was prepared from culture obtained by continuous streaking. The isolated culture was identified morphologically by Gram staining and confirmed by biochemical characteristics. Rice polishing was sieved to remove larger particles. Then it was distributed to 4 treatments in triplicates. Treatments were represented as rice polishing (RP), rice polishing plus Saccharomyces culture (RPSC), rice polishing plus ammonium sulphate (RPAS), rice polishing plus Saccharomyces culture plus ammonium sulphate (RPSCAS).Fermentation was provided for 144 hours at 320C,while samples were collected after every 24 hours. Samples were dried, ground and subjected to proximate analysis. It was observed that protein content was increased from 11% to 21.51% and maximum increment was obtained after 144 hours of incubation in RPSC treatment. Ether extract and ash were increased from 14% and 10% to 16.96% and 11.11% in RPSCAS respectively. A significant reduction in neutral detergent fiber was observed after fermentation. It is concluded that Saccharomyces cerevisiae has potential to improve mineral and protein contents of rice polishing by fermentation process with or without addition of nitrogen source.

Molybdophyllite: crystal chemistry, crystal structure, OD character and modular relationships with britvinite

AbstractA detailed crystal-chemical study of the complex layered silicate molybdophyllite was conducted using single-crystal X-ray diffraction (XRD) methods, supplemented by powder XRD, infrared (IR) and Raman spectroscopic studies, chemical analyses by energy-dispersive spectrometry (EDS) on a scanning electron microscope (SEM), and electron probe microanalysis (EPMA). The results, based on several samples from both Långban and Harstigen, Filipstad, Sweden, show that the crystal structure of molybdophyllite has an order-disorder (OD) character. The latter is especially evident in specimens from Långban which display a complex diffraction pattern characterized by the simultaneous presence of sharp spots, diffuse reflections and continuous streaks. The sharp reflections define the unit cell of the family structure (a = 3.124, c = 41.832 Å, space group R32). Two main polytypes (maximum degree of order structures) are indicated by the OD approach: a trigonal one and a monoclinic one; the latter polytype is the most common in the samples that were studied and has space group C2, with a = 16.232(6), b = 9.373(2), c = 14.060(3) Å, b = 97.36(4)º and V = 2121.5(10) Å3.The crystal structure determination [R1= 0.096], together with the EPMA, IR and Raman data, reveal that molybdophyllite is built up by a regular alternation of complex layers with a composition {Mg9[Si10O28(OH)8][OPb4]2}6+and simple layers with a composition [(CO3)3·H2O]6–, leading to the ideal crystal-chemical formula Pb8Mg9[Si10O28(OH)8|O2|(CO3)3]·H2O (Z = 2).This contribution is mainly devoted to the results obtained for molybdophyllite sensu stricto, but new data for britvinite [i.e. 'molybdophyllite-18 Å'] are also presented and its modular relationship with molybdophyllite is discussed.

Microstructural and surface residual stress development during low-temperature gaseous nitriding of Fe-3.07at.%Mo alloy

Abstract Fe-3.07at.%Mo alloy specimens were nitrided at 480 °C in a NH3/H2 gas mixture applying a nitriding potential of 0.25 atm−1/2. Selected area electron diffraction patterns (SADPs) of the nitrided zone showed continuous streaking in <100>α-Fe directions, which indicates the presence of fine, nano-sized precipitate platelets, with a coherent interface parallel to the {100} planes of the ferrite (a) matrix. The X-ray diffractograms, recorded from the specimen surface, showed an asymmetric broadening of the ferrite-matrix reflections which was especially pronounced for the (200) reflections, which hints at a tetragonal distortion of the (microstressed) ferrite matrix surrounding the precipitates. These misfitting, nano-sized precipitates cause a relatively high hardness as well as a compressive residual macrostress parallel to the surface in the nitrided zone adjacent to the surface: 900HV0.05 and 1100MPa, respectively.

Rapid, continuous streaking of tremor in Cascadia

Nonvolcanic tremor is a recently discovered weak seismic signal associated with slow slip on a fault plane and has potential to answer many questions about how faults move. Its spatiotemporal distribution, however, is complex and varies over different time scales, and the causal physical mechanisms remain unclear. Here we use a beam backprojection method to show rapid, continuous, slip‐parallel streaking of tremor over time scales of several minutes to an hour during the May 2008 episodic tremor and slip event in the Cascadia subduction zone. The streaks propagate across distances up to 65 km, primarily parallel to the slip direction of the subduction zone, both updip and downdip at velocities ranging from 30 to 200 km/h. We explore mainly two models that may explain such continuous tremor streaking. The first involves interaction of slowly migrating creep front with slip‐parallel linear structures on the fault. The second is pressure‐driven fluid flow through structurally controlled conduits on the fault. Both can be consistent with the observed propagation velocities and geometries, although the second one requires unlikely condition. In addition, we put this new observation in the context of the overall variability of tremor behavior observed over different time scales.

Vastmanlandite-(Ce) a new lanthanide- and F-bearing sorosilicate mineral from Vastmanland, Sweden: description, crystal structure, and relation to gatelite-(Ce)

Vastmanlandite-(Ce), ideally (Ce,La) 3 CaAl 2 Mg 2 [Si 2 O 7 ][SiO 4 ] 3 F(OH) 2 , is a new mineral species from the Vastmanland county, Bergslagen region, Sweden. Together with more Fe-rich, F-poor members, it forms solid solutions that are important for lanthanide sequestration in the Bastnas-type skarn deposits in Vastmanland. At the type locality (Malmkarra, Norberg district) it occurs as anhedral grains 0.2–3 mm across, in association with fluorbritholite-(Ce), tremolite, a serpentine mineral, magnetite, dollaseite-(Ce) and dolomite. The mineral is allanite-like in appearance; it is dark brown, translucent, with vitreous luster, and has good cleavage parallel to {001}, uneven to conchoidal fracture, and a yellowish gray streak; D calc = 4.51(2) g·cm −3 and Mohs hardness ≈ 6. Optically it is biaxial (-), with α = 1.781 (4), β calc = 1.792, γ = 1.810(4) and 2V α = 75(5)°. Chemical analysis by electron-microprobe and 57 Fe Mossbauer spectroscopy yield: La 2 O 3 13.65, Ce 2 O 3 23.90, Pr 2 O 3 2.07, Nd 2 O 3 6.28, Sm 2 O 3 0.42, Gd 2 O 3 0.15, Y 2 O 3 0.18, CaO 4.65, FeO 1.14, Fe 2 O 3 2.69, MgO 5.51, Al 2 O 3 8.58, TiO 2 0.04, P 2 O 5 0.05, SiO 2 26.61, F 1.06, H 2 O calc 1.61, O ≡ F −0.45, sum 98.14. Vastmanlandite-(Ce) is monoclinic, P2 1 / m , with a = 8.939(1), b = 5.706(1), c = 15.855(2) A, β = 94.58(1)°, V = 806.1(2) A 3 , and Z = 2 (single-crystal data). The eight strongest lines in the X-ray powder diffraction pattern are [ d (in A) ( I/I 0 )( hkl )]: 15.81(16)(001), 4.65(10)(111), 3.50(20)(210), 2.983(100)(014), 2.685(13)(121), 2.678(11)(205), 2.625(19)(311), and 2.187(15)(402). The crystal structure was determined using single-crystal X-ray diffraction data and refined to R1( F ) = 1.73% for 2864 9observed9 reflections with F o > 4σ( F o ). Vastmanlandite-(Ce) is nearly isotypic to gatelite-(Ce), ideally Ce 3 CaAl 2 AlMg[Si 2 O 7 ][SiO 4 ] 3 O(OH) 2 , and can be described as a regular dollaseite-(Ce)-tornebohmite-(Ce) polysome. The occurrence of extremely weak, continuous streaking in the diffraction patterns, and the presence of two pairs of mirror-related atoms in the tornebohmite-(Ce) module indicate that the structure model represents an average structure, unlike the situation in gatelite-(Ce) where there are no continuous streaks but instead, due to atomic ordering, sharp superstructure reflections resulting in a different unit cell.

Upscaling relative permeabilities in a structured porous medium

Upscaling of multi-phase flow problems for a heterogeneous porous medium requires modification of constitutive functions at the grid-block scale. A particular type of heterogeneity that has important environmental consequences involves thin, continuous streaks of high permeability through lower-permeability background rocks. These streaks, which may correspond to features like abandoned wells in mature sedimentary basins, can become preferential flow paths for an invading fluid. Quantification of flow through these types of heterogeneities in deep, geological formations is necessary for estimates of migration and possible leakage of injected fluids such as hazardous liquid wastes, municipal liquid wastes, and, possibly, carbon dioxide. One of the important constitutive functions for proper estimation of flow through these flow paths is the relative permeability function. In the simple case of a single high-permeability streak in a uniform rock matrix, with both materials having identical (local) relative permeability functions, the upscaled relative permeability must be changed significantly to capture the proper leakage. Standard petroleum reservoir pseudo-functions for relative permeability capture the general features of the upscaled function, but they still produce errors of several hundred percent in the leakage estimation. Detailed three-dimensional numerical simulations and associated upscaled calculations demonstrate the proper form for the upscaled relative permeability, and provide a modified derivation of pseudo-functions to capture the leakage behavior in upscaled models.

Improved Productivity Justifies World Record Underbalanced Perforating Operation

Abstract A Dutch onshore gas well was drilled to a total depth of 5,136 m along hole (3,700 m true vertical depth) with a maximum deviation of 89 degrees. The well was completed with 193.7 mm (7 5/8 in.) 13 ﹪ chrome (Cr13) tubing with a 177.8 mm (7 in.) cemented liner across the reservoir providing fullore access to the pay zone. Due to the very stratified nature of the reservoir, the long-term sustained production depended on achieving vertical connectivity with all the layers. In order to achieve this and maximize productivity, a single run underbalanced perforating operation was required. Due to coiled tubing limitations in this deep, high pressure well, a hydraulic workover unit was selected to deploy and retrieve the guns. A total gross interval of 1,026 m was perforated in one run utilizing 85.725 mm (33/8 in.) deep penetrating guns and thereafter snubbed from the well under live conditions (46 MPa at surface). To date, it is understood that this is the longest section of guns conveyed, fired underbalanced, and deployed out of a live well. This paper addresses the perforating technique selection, the planning and execution process, the major operational learning points, and discusses final productivity results which demonstrate the validity of this technique. Introduction The Anjum reservoir is a Rotliegendes sandstone at a true vertical depth of 3,700 m. Reservoir pressure and temperature are high for onshore Netherlands at 56 MPa and 137 °CDATA[C, respectively. Following discovery of the prospect in 1992 with the Anjum 1 exploration well, Anjum 4 was drilled as the second well in the field. It was designed as a combined appraisal/development well with the objective of providing capacity in the region of six to seven million m3/day. The reservoir is of a highly stratified nature with a number of high permeability features, some of which are on a centimetre scale. The Upper-Slochteren gas-bearing interval is split up into six discrete units, which are correlatable across the whole of the North Netherlands area. The upper three sands dominate in terms of reservoir quality and productivity. There exist two significant and continuous high permeability streaks (HPS) which, if targeted, would provide initial high productivity. However, the longterm sustained production depends on achieving vertical connectivity with all reservoir zones. Therefore, in order to maximize exposure across all intervals, and to provide the maximum connectivity with the individual layers, a sub-horizontal well was designed. A cemented and perforated liner was selected, since it provided the opportunity to effectively bypass near wellbore drilling induced damage. Secondary benefits of this design are that it provides maximum selectivity (water shut off, stimulation etc.) and through the utilization of deep penetrating perforating guns reduces non-Darcy turbulent effects. The well was completed with a 177.8 mm (7 in.) Cr13 liner across the pay zone and a 193.7 mm (7 5/8 in.) Cr 13 monobore completion with a tubing retrievable safety valve to provide maximum wellbore access (Figure 1).

Transmission electron microscopy study of gaudefroyite,

A transmission electron microscopy (TEM) study of gaudefroyite, \(Ca_{8}Mn_{6}^{3+}[(BO_{3})_{6}(CO_{3})_{2}O_{6}]\) , from the Wessels mine, Kalahari manganese field, South Africa, shows strong, continuous streaking in selected-area electron diffraction (SAED) patterns. The pseudo-hexagonal parameters for gaudefroyite are a = 10.606(1) and c = 5.896(1) A. The symmetry of gaudefroyite is lower than hexagonal because of the streaked reflections. The CO 3 groups in the large 6 3 channels are ordered in two different ways and this ordering gives rise to two different types of channels, A and B. The A and B channels occur in a 1:1 ratio and these channels are partially ordered and give rise to the continuous streak reflections in gaudefroyite.

A paracrystalline description of defect distributions in wüstite, Fe1−xO

Diffuse X-ray scattering data from a crystal of wustite, Fe0.943O, are presented. Satellite reflections corresponding to an incommensurate repeat distance of ∼2.7a in all three cubic directions were observed (the P′ phase). The satellites were diffuse, anisotropically elongated, interconnected by weaker continuous streaks, and negligible in intensity beyond first order. Monte Carlo computer simulations have been carried out which demonstrate that this diffraction behavior is consistent with defect clusters forming a paracrystalline (or highly distorted) lattice. The paracrystalline distribution which best fits the observations is such that the spacing between defects tends to be maintained fairly constant, but relative lateral translations may occur more variably. When these lateral translations are suppressed, additional superlattice peaks appear which are consistent with the P″ phase diffraction patterns. The diffuse satellites are systematically more intense on the low-angle side of a Bragg reflection than on the high-angle side. This behavior may be understood in terms of the well-known atomic size effect and is consistent with a local contraction of the structure around regions of low scattering power (defect clusters) and compensating expansion in other parts of the structure.

Morphology of .GAMMA." Precipitates in a Ni-15Cr-8Fe-6Nb Alloy.

The morphology of γ'' precipitates extracted from a nickel-base superalloy, a modified NCF 3 type alloy (X-750M), was investigated mainly by transmission electron microscopy (TEM). The TEM images using carbon extraction replica of γ'' precipitates were clearer than those using electro-polished thin film. The γ'' precipitates were disc shaped in the early stage of aging and became elliptic or irregular shaped plates in latter at up to 1033 K, while they grew in rectangular shaped plates in latter at 1073 K. Many of larger γ'' precipitates in the specimens aged at up to 1033 K exhibited a considerable amount of internal fringe contrast. Selected area diffraction pattern from them showed continuous streaks normal to {112}γ''. The internal contrast is thought to be due to stacking faults. The internal fringe contrast was not observed in γ'' precipitates in the specimen aged at 1073 K.

Radioactive 2-DG incorporation patterns in the mesial frontal cortex of task-performing monkeys

The pattern of radioactive 2-deoxy- d-glucose (2-DG) uptake in the rostral mesial cortex was investigated in seven hemispheres of four task-performing monkeys (a delayed-response task performed with a forelimb). A two-dimensional 2-DG map was constructed from frontal sections. Blob-like 2-DG incorporation sites (2-DG active sites) were observed in single frontal sections, e.g., in the anterior cingulate gyms (CiG) and supplementary and primary motor cortices in the mesial surface, and around the superior precentral sulcus in the premotor area. Blob-like 2-DG incorporation sites were also observed in the medial part of the dorsal frontal cortex near the midline. However, most of these blob-like 2-DG active sites were revealed in fact not to be blobs. They formed rostrocaudally continuous streaks when they were constructed in a two-dimensional map. Streaks fused with one another in some areas, and gave off branches in other areas. These 2-DG uptake patterns were similar between the paired left and right hemispheres of three brains. It is highly probable that these 2-DG active streaks (or blobs) reflected neuronal activity related to somatomotor and/or eye movements, because the 2-DG-labeled areas included motor, premotor, supplementary motor, and possibly part of the supplementary eye fields. It is also probable that this 2-DG incorporation was related to cognitive or memory functions, because neuronal activity related to performance of a delayed-response was reported in the rostral mesial cortex and in the CiG.

A Paracrystalline Description of Defect Distributions in Wüstite, Fe1-xO

Diffuse X-ray scattering data from a crystal of wüstite, Fe0.943O, are presented. Satellite reflections corresponding to an incommensurate repeat distance of ∼2.7a in all three cubic directions were observed (the P′ phase). The satellites were diffuse, anisotropically elongated, interconnected by weaker continuous streaks, and negligible in intensity beyond first order. Monte Carlo computer simulations have been carried out which demonstrate that this diffraction behavior is consistent with defect clusters forming a paracrystalline (or highly distorted) lattice. The paracrystalline distribution which best fits the observations is such that the spacing between defects tends to be maintained fairly constant, but relative lateral translations may occur more variably. When these lateral translations are suppressed, additional superlattice peaks appear which are consistent with the P″ phase diffraction patterns. The diffuse satellites are systematically more intense on the low-angle side of a Bragg reflection than on the high-angle side. This behavior may be understood in terms of the well-known atomic size effect and is consistent with a local contraction of the structure around regions of low scattering power (defect clusters) and compensating expansion in other parts of the structure.

Supersonic propagation of an ionization front in low density foam targets driven by thermal radiation.

Observations of the sustained propagation of a supersonic ionization front, produced by an intense pulse of thermal radiation in low density foam targets, are reported. The position of the front was observed with a high resolution soft x-ray imaging system (at 50 and 70 \AA{}), using 1D continuous streaks and 2D gated images. The experimental observations were in good agreement with 1D and 2D radiation hydrodynamic code simulations.

TEM study of synthetic hillebrandite (Ca2SiO4 · H2O)

Hillebrandite (dicalcium silicate hydrate) was produced by a hydrothermal process. Its crystal structure and microstructures were investigated by conventional TEM and HREM. Most hillebrandite fibers showed their elongation to be parallel to the b axis and tended to lie on the {001} cleavage planes. Selected area diffraction patterns frequently displayed continuous streaking, and corresponding dark-field images revealed stacking disorders perpendicular to the fiber axis. The morphology, stacking disorders, and extinction conditions of {hkO} reflections and hillebrandite resembled those of the minerals wollastonite (CaSiO3) and pectolite (Ca2NaH[SiO3]3). Periodic (100) faulting with a displacement vector 1/2 b is suggested to be the major origin of the streaking and the systematic absences in hillebrandite.

TEM characterization of synthetic hillebrandite: Structure, microstructure, and dehydration

Hillebrandite (Ca2SiO4•H2O) occurs in nature as a white, fibrous mineral. Synthetic hillebrandite was prepared hydrothemally from calcia and silica. On heating, hillebrandite dehydrated to β-Ca2SiO4 which is stable at room temperature. The crystal structure, microstructures and the dehydration mechanism of the synthetic hillebrandite prepared by Ishida et. al were investigated by conventional TEM, HREM, and in situ hot-stage TEM.Most hillebrandite fibers showed their fiber axis to be parallel to the b axis and tended to lie on {001} cleavage planes. SADP’s frequently displayed continuous streaking, and corresponding dark field images revealed stacking disorders perpendicular to the fiber axis (Fig. 1). The observed [001] SADP (Fig. 2) was very different from the expected [001] SADP based on published XRD data (space group, P21/a). For all hk0 reflections, (i) if k = odd, no individual spots are shown but weak continuous streaking exists, (ii) if k = 2, reflections of h = even are extinct, and (iii) if k = 4, reflections of h = odd are extinct.

A color-coded particle tracking velocimeter with application to natural convection

This paper introduces a novel concept of the image-processing technique to visualize a two-dimensional flow field and to generate streaks with embedded time marks in real time. Grey levels of a pixel are used in this work to encode the temporal information rather than the intensity of particle trajectories used in conventional image-processing systems. To do this, the incoming video image is first binarized by a step function predefined in an input look-up table, with the height of the step varying with time to bear temporal marks. A real-time arithmetic-logic unit and an image-frame buffer are used to accumulate the images. These processes result in continuous streaks with embedded time marks which have many advantages over those recorded by conventional techniques. Pseudo-color output look-up tables and color monitor provide more direct and intuitive means for human visual perception. This color-coded particle tracking velocimetry was applied to investigate natural convection in an enclosure heated from below with an isothermal extrusion. By quantifying the color-coded streaks, velocity vectors were obtained at a discrete number of points with less labor. The present technique provides an elaborate tool for simultaneous qualitative and quantitative realizations of steady and slowly varying flow fields.

Lattice imaging of metastable TiSi2

The microstucture of metastable C49-TiSi2 was studied by high-resolution transmission electron microscopy in a bilayer thin film of Ti and Si annealed at 700 °C. Large grains (300–400 nm) of C49-TiSi2 phase with high density of stacking faults on (010) planes were observed. A preferred orientation among the C49-TiSi2 grains was identified, and the grains were aligned along the [010] with slight misorientation. The diffraction pattern from the metastable TiSi2 showed continuous streaks superimposed by discrete spots along hk0 reciprocal lattice rows, indicating the presence of polytypism. Lattice imaging of polytypic TiSi2 has been obtained and it showed that the structure is nonperiodic and one dimensionally disordered due to the stacking faults. The finding of metastable TiSi2 associated with polytypism suggests that its structure could be conveniently represented by various stackings of atomic planes along the [010] direction. An atomic model is proposed to explain the origin of polytypism. It is shown that the arrangement of atoms in C49-TiSi2 structure has four equivalent positions.

The stability and structure of [formula omitted

The stability of the phase Cs x[ Ti 2− x 4 □ x 4 ] O 4 , □ = vacancy, in the Cs 2OTiO 2 system has been studied in the temperature range 800−1120°C. The phase has a narrow range of homogeneity with 0.61 < x < 0.65. Structure refinements were carried out for X-ray intensity data from two crystals obtained from melts with TiO 2:CsO 0.5 molar ratios of 2.0 and 3.2. The crystals have orthorhombic symmetry, Immm, a 0 = 3.83, b 0 = 17.00, c 0 = 2.96 Å. The refinements are consistent with the structural model of Hervieu and Raveau ( Rev. Chim. Minér. 18, 642 (1981)) in which (010) corrugated layers of titanium-oxygen octahedra, containing disordered titanium vacancies, are separated by planes of cesium ions. Long-exposure precession photographs showed diffuse superlattice diffraction effects in the form of continuous streaks parallel to b∗ 0 . These have been analyzed in terms of models for two-dimensional ordering of the interlayer cesium ions. Annealing of melted samples below 700°C causes a transformation of the I-centered structure to a C-centered structure of the K x ( M y Ti 2− y )O 4 type in which 3-D ordering of cesium occurs.

X-Ray Diffraction and Transmission Electron Microscopy Study of One-Dimensional Disorder Polytypes in SiC

Silicon carbide crystallizes into several structural modifications whose c-periodicities vary from 1 nm to more than 100 nm. Its high period structures are found to consist of intergrowth of smaller period structures at the unit cell level. The X-ray diffraction studies show that SiC crystals often possess one-dimensional disorder which is characterized by continuous streaks in X-ray diffraction patterns along ho.1 reciprocal lattice rows. However, it is shown that these streaks can also arise as a result of extremely high c-periodicities of the crystals as their ho.1 spots cannot be resolved easily. This contribution reports the observation of only few representative cases of so-called one-dimensional disordered crystals as observed in their X-ray and electron diffractions with lattice imaging.