Spot Core Research Articles

Femtosecond laser direct-writing of high quality first-order Bragg gratings with arbitrary complex apodization by phase modulation.

Femtosecond laser direct-writing is an attractive technique to fabricate fiber Bragg gratings and to achieve through-the-coating inscription. In this article, we report the direct inscription of high-quality first-order gratings in optical fiber, without the use of an index-matching medium. A new alignment technique based on the inscription of weak probe gratings is used to track the relative position between the focal spot and fiber core. A simple and flexible method to precisely control the position of each grating plane is also presented. With this method, periodic phase modulation of grating structures is achieved and used to inscribe arbitrary apodization and phase profiles. It is shown that a burst of multiple laser pulses used to inscribe each grating plane leads to a significant increase in the grating strength, while maintaining low insertion loss, critical for many applications.

Active Basalt Alteration at Supercritical Conditions in a Seawater‐Recharged Hydrothermal System: IDDP‐2 Drill Hole, Reykjanes, Iceland

AbstractThe 4.5 km deep IDDP‐2 drill hole was drilled at Reykjanes, Iceland, in an active seawater‐recharged hydrothermal system on the landward extension the Mid‐Atlantic Ridge. Drilling targeted a well‐defined hydrothermal up‐flow zone feeding the Reykjanes geothermal reservoir, which produces fluids compositionally equivalent to basalt‐hosted deep sea hydrothermal vents. Spot cores recovered from depths between 3,648 to 4,659 m depths consist of pervasively altered sheeted diabase dikes. The shallowest core has an alteration mineral assemblage similar to the producing geothermal reservoir but is being overprinted by the underlying Hornblende Zone assemblage dominated by labradorite and hornblende. The deepest cored section (4,634–4,659 m) retains a diabasic texture, but all primary minerals are replaced or have changed composition. Plagioclase ranges from An30 to An99 and igneous augite is replaced by intergrown hornblende, clinopyroxene, and orthopyroxene. Hydrothermal biotite and potassium feldspar formed locally due to reaction with a phase‐separated brine, indicated by co‐existing vapor‐rich and salt + vapor‐rich fluid inclusions. Seawater‐derived supercritical hydrothermal fluid entering the bottom of the bore hole actively phase separates due pressure drop controlled by the fluid levels in the drill hole. Felsic veins, present in trace amounts, record a continuous transition from magmatic to hydrothermal conditions, including incipient hydrous melting. The vertical changes observed in mineralogy and mineral chemistry indicate that fluids from the deep high temperature reaction zone can undergo significant cooling and reaction with host rocks along their path to the seafloor.

Spot Dynamics of a Reaction-Diffusion System on the Surface of a Torus

Quasi-stationary states consisting of localized spots in a reaction-diffusion system are considered on the surface of a torus with major radius $R$ and minor radius $r$. Under the assumption that these localized spots persist stably, the evolution equation of the spot cores is derived analytically based on the higher-order matched asymptotic expansion with the analytic expression of the Green's function of the Laplace--Beltrami operator on the toroidal surface. Owing to the analytic representation, one can investigate the existence of equilibria with a single spot, two spots, and the ring configuration where $N$ localized spots are equally spaced along a latitudinal line with mathematical rigor. We show that localized spots at the innermost/outermost locations of the torus are equilibria for any aspect ratio $\alpha=\frac{R}{r}$. In addition, we find that there exists a range of the aspect ratio in which localized spots stay at a special location of the torus. The theoretical results and the linear stability of these spot equilibria are confirmed by solving the nonlinear evolution of the Brusselator reaction-diffusion model by numerical means. We also compare the spot dynamics with the point vortex dynamics, which is another model of spot structures.

The Discovery of the Hepatitis D Virus: Three Princes of Serendip and the Recognition of Autoantibodies to Liver-Kidney Microsomes.

The Discovery of the Hepatitis D Virus: Three Princes of Serendip and the Recognition of Autoantibodies to Liver-Kidney Microsomes.

Development of a polar-view Kirkpatrick-Baez X-ray microscope for implosion asymmetry studies.

The development of a polar-view Kirkpatrick-Baez microscope, fielded in the upper polar zone of the Shenguang-III laser fusion facility, is presented. With this microscope, the resolving power of polar-direction X-ray imaging diagnostics is improved, to the 3 ~5 μm scale. The microscope is designed for implosion asymmetry studies, with response energy points at 1.2 keV, 3.5 keV, and 8 keV. A biperiodic multilayer scheme is adopted to accommodate multiple implosion stages. We present the overall optical system design, target aiming scheme, characteristic composite imaging diagnostic experiments and initial results. The inertial-driven quasi-one-dimensional spherical implosions were observed from orthogonal directions with a convergence ratio of ~14.4. Fine features of the stagnating hot spot core are also resolved.

Mitigating non‐uniform heat generation induced hot spot(s) in multicore processors using nanofluids in parallel microchannels

The present paper illustrates experimentally the impact of non-uniform heat generation in a microprocessor on the hot spot distribution and the method to cool the same, efficiently employing parallel microchannel cooling configurations. It is often assumed during design of microprocessor cooling systems that the heat load emitted by the device is uniform, however real time tracking of the device shows that such assumptions are far from the reality. An Intel® Core™ i7–4770 3.40 GHz quad core processor has been experimentally mimicked using heat load data retrieved from a real microprocessor with non-uniform core activity. Parallel microchannel based heat spreader configurations using U, I and Z type flow configurations have been employed to mitigate the thermal load from the mimicked device. The observations clearly show that the microchannel cooling system experiences two forms of hot spots, one due to the flow maldistribution within the system and the other due to the additional non-uniform heat generation by the device. The hot spots have been shown to exhibit drastically different shapes and core temperatures and this has been verified through simulations and infrared thermography. To efficiently cool hot spot core temperatures, nanofluids have been employed and ‘smart cooling’ has been observed and the same has been explained based on nanoparticle slip mechanisms. The present work shows that the notion that high flow maldistribution leads to high thermal maldistribution, is not always true and existing maldistribution can be effectively utilized to tackle specific hot spot location. The present work can be important to design cooling mechanisms for real microprocessors with high core activity leading to non-uniform hot spot formation probabilities.

Selecting Optimal Parallel Microchannel Configuration(s) for Active Hot Spot Mitigation of Multicore Microprocessors in Real Time

Design of effective microcooling systems to address the challenges of ever increasing heat flux from microdevices requires deep examination of real-time problems and has been tackled in depth. The most common (and apparently misleading) assumption while designing microcooling systems is that the heat flux generated by the device is uniform, but the reality is far from this. Detailed simulations have been performed by considering nonuniform heat load employing the configurations U, I, and Z for parallel microchannel systems with water and nanofluids as the coolants. An Intel® Core™ i7-4770 3.40 GHz quad core processor has been mimicked using heat load data retrieved from a real microprocessor with nonuniform core activity. This study clearly demonstrates that there is a nonuniform thermal load induced temperature maldistribution along with the already existent flow maldistribution induced temperature maldistribution. The suitable configuration(s) for maximum possible overall heat removal for a hot zone while maximizing the uniformity of cooling have been tabulated. An Eulerian–Lagrangian model of the nanofluids shows that such “smart” coolants not only reduce the hot spot core temperature but also the hot spot core region and thermal slip mechanisms of Brownian diffusion and thermophoresis are at the crux of this. The present work conclusively shows that high flow maldistribution leads to high thermal maldistribution, as the common prevalent notion is no longer valid and existing maldistribution can be effectively utilized to tackle specific hot spot location, making the present study important to the field.

Clocking Effects of Inlet Nonuniformities in a Fully Cooled High-Pressure Vane: A Conjugate Heat Transfer Analysis

A high-pressure vane (HPV) equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side, while the leading edge (LE) is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-averaged Navier–Stokes simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and HPVs are then investigated, considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first in which hot spot and swirl core are aligned with passage; and the second in which they are aligned with the LE. Comparisons between metal temperature distributions obtained from conjugate heat transfer (CHT) simulations are performed, evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The LE aligned configuration is determined to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage-aligned case. A strong sensitivity to both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.

Distinct Rayleigh Scattering from Hot Spot Mutant p53 Proteins Reveals Cancer Cells

The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor.

Spectroscopy of Single Vacuum Arc Cathode Spots With Improved Sensitivity

Recently, we reported on the optical emission of vacuum arc discharges with a single cathode spot. The discharges were initiated by rectangular voltage pulses of 100-ns length produced by a cable generator. In combination with the application of a liquid Ga-In alloy cathode and ultrahigh vacuum conditions, a high reproducibility was obtained. An improvement of the sensitivity and the signal-to-noise ratio was achieved by the replacement of the streak camera by an intensified charge-coupled device camera. Thus, the accumulation of calibrated spectra with high temporal, spatial, and wavelength resolution was possible. Distinct differences in the temporal development of the atomic and ionic line intensities were found depending on the spatial position, that is, comparing the spot core and the spot surrounding.

Relationships between storage disorders and fruit calcium contents, lipoxygenase activity, and rates of ethylene evolution and respiration in ‘Royal Delicious’ apple (Malus × domestica Borkh.)

SummaryExperiments were conducted to determine the relationships between the occurrence of storage disorders in ‘Royal Delicious’ apple (Malus ×domestica Borkh.) and fruit Ca2+ ion contents, rates of ethylene evolution and respiration, and lipoxygenase (LOX) activity. Apples were stored at 0º ± 1ºC and 90 – 95% relative humidity and sampled each month, up to 6 months, for storage disorders, fruit Ca2+ ion contents, rates of ethylene evolution and respiration, and LOX activity. Storage disorders such as bitter pit, cork spot, and brown core appeared after 3 months and increased in frequency at subsequent samplings. Regardless of the presence or absence of storage disorders, fruit showed a decline in Ca2+ ion concentration during storage. Ca2+ ion concentrations (means of 3, 4, 5, and 6 month samples) were significantly higher in disorder-free fruit [0.419 mg g–1 dry weight (DW)] than in fruit showing bitter pit (0.329 mg g–1 DW) or cork spot (0.340 mg g–1 DW), but were not significantly higher than in fruit with brown core (0.393 mg g–1 DW). Conversely, LOX activity was significantly lower in disorder-free fruit [0.168 µmoles linolenic acid oxidised min–1 g–1 fresh weight (FW)] compared to symptomatic fruit. LOX activity increased with the duration of storage in all fruit samples. The rates of ethylene evolution (58.5 µl C2H4 kg–1 FW fruit h–1) and respiration (16.0 ml CO2 kg–1 FW fruit h–1) were significantly lower in disorder-free fruit than in symptomatic fruit. The rates of ethylene evolution and respiration increased between 3 – 5 months in storage. After 5 months in storage, they remained stable or declined in all fruit. The correlations (R2) between Ca2+ ion content vs. the presence of physiological disorders such as bitter pit (–0.77), cork spot (–0.75), and brown core (–0.64), and between Ca2+ ion contents vs. LOX activity were strongly negative (–0.94). In contrast; the correlation between LOX activity vs. physiological disorders was strongly positive. Our study concluded that an inverse relationship existed between fruit Ca2+ ion content and the occurrence of bitter pit, cork spot, and/or brown core, and between fruit Ca2+ ion content and LOX activity. Moreover, the relationship between LOX activity and the presence of storage disorders was strongly positive.

Lithology and internal structure of the San Andreas fault at depth based on characterization of Phase 3 whole-rock core in the San Andreas Fault Observatory at Depth (SAFOD) borehole

We characterize the lithology and structure of the spot core obtained in 2007 during Phase 3 drilling of the San Andreas Fault Observatory at Depth (SAFOD) in order to determine the composition, structure, and deformation processes of the fault zone at 3 km depth where creep and microseismicity occur. A total of approximately 41 m of spot core was taken from three separate sections of the borehole; the core samples consist of fractured arkosic sandstones and shale west of the SAF zone (Pacific Plate) and sheared fine-grained sedimentary rocks, ultrafine black fault-related rocks, and phyllosilicate-rich fault gouge within the fault zone (North American Plate). The fault zone at SAFOD consists of a broad zone of variably damaged rock containing localized zones of highly concentrated shear that often juxtapose distinct protoliths. Two zones of serpentinite-bearing clay gouge, each meters-thick, occur at the two locations of aseismic creep identified in the borehole on the basis of casing deformation. The gouge primarily is comprised of Mg-rich clays, serpentinite (lizardite ± chrysotile) with notable increases in magnetite, and Ni-Cr-oxides/hydroxides relative to the surrounding host rock. The rocks surrounding the two creeping gouge zones display a range of deformation including fractured protolith, block-in-matrix, and foliated cataclasite structure. The blocks and clasts predominately consist of sandstone and siltstone embedded in a clay-rich matrix that displays a penetrative scaly fabric. Mineral alteration, veins and fracture-surface coatings are present throughout the core, and reflect a long history of syn-deformation, fluid-rock reaction that contributes to the low-strength and creep in the meters-thick gouge zones.

Design, Manufacture, and Operation of a Core Barrel for the Iceland Deep Drilling Project (IDDP)

The science program of the Iceland Deep Drilling Project (IDDP) requires as much core as possible in the transition zone to supercritical and inside the supercritical zone (>374°C), in the depth interval 2400–4500 m. The spot coring system selected has a 7 ¼ (184.15 mm) OD at 10 m length and collects a 4 (101.6 mm) diameter core using an 8 ½ (215.9 mm) OD core bit. It incorporates design characteristics, materials, clearances and bearings compatible with operation of the core barrel at temperatures as high as 600°C. Special attention was given to the volume of flushing which could be applied to the core barrel and through the bit while running in and out of the borehole and while coring. In November 2008 a successful spot coring test using the new core barrel was performed at 2800 m depth in the production well RN-17 B at Reykjanes, Iceland, where the formation temperature is 322°C. A 9.3-m hydrothermally altered hyaloclastite breccia was cored with 100% core recovery, in spite of it being highly fractured. A core tube data logger was also designed and placed inside the inner barrel to monitor the effectiveness of cooling. The temperature could be maintained at 100°C while coring, but it reached 170°C for a very short period while tripping in. The effective cooling is attributed to the high flush design and a top drive being employed, which allows circulation while tripping in or out, except for the very short time when a new drill pipe connection is being made.

Design, Manufacture, and Operation of a Core Barrel for the Iceland Deep Drilling Project (IDDP)

The science program of the Iceland Deep Drilling Project (IDDP) requires as much core as possible in the transition zone to supercritical and inside the supercritical zone (>374°C), in the depth interval 2400–4500 m. The spot coring system selected has a 7 1/4" (184.15 mm) OD at 10 m length and collects a 4" (101.6 mm) diameter core using an 8 1/2" (215.9 mm) OD core bit. It incorporates design characteristics, materials, clearances and bearings compatible with operation of the core barrel at temperatures as high as 600°C. Special attention was given to the volume of flushing which could be applied to the core barrel and through the bit while running in and out of the borehole and while coring. In November 2008 a successful spot coring test using the new core barrel was performed at 2800 m depth in the production well RN-17 B at Reykjanes, Iceland, where the formation temperature is 322°C. A 9.3-m hydrothermally altered hyaloclastite breccia was cored with 100% core recovery, in spite of it being highly fractured. A core tube data logger was also designed and placed inside the inner barrel to monitor the effectiveness of cooling. The temperature could be maintained at 100°C while coring, but it reached 170°C for a very short period while tripping in. The effective cooling is attributed to the high flush design and a top drive being employed, which allows circulation while tripping in or out, except for the very short time when a new drill pipe connection is being made. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.10.05.2010" target="_blank">10.2204/iodp.sd.10.05.2010</a>

Paleomagnetic reorientation of San Andreas Fault Observatory at Depth (SAFOD) core

We present a protocol for using paleomagnetic analysis to determine the absolute orientation of core recovered from the SAFOD borehole. Our approach is based on determining the direction of the primary remanent magnetization of a spot core recovered from the Great Valley Sequence during SAFOD Phase 2 and comparing its direction to the expected reference field direction for the Late Cretaceous in North America. Both thermal and alternating field demagnetization provide equally resolved magnetization, possibly residing in magnetite, that allow reorientation. Because compositionally similar siltstones and fine‐grained sandstones were encountered in the San Andreas Fault Zone during Stage 2 rotary drilling, we expect that paleomagnetic reorientation will yield reliable core orientations for continuous core acquired from directly within and adjacent to the San Andreas Fault during SAFOD Phase 3, which will be key to interpretation of spatial properties of these rocks.

04/02409 Porosity and permeability of the Tiwi geothermalfield, Philippines, based on continuous and spot core measurements: Stimac, J. A. et al. Geothermics, 2004, 33, (1–2), 87–107

04/02409 Porosity and permeability of the Tiwi geothermalfield, Philippines, based on continuous and spot core measurements: Stimac, J. A. et al. Geothermics, 2004, 33, (1–2), 87–107

Porosity and permeability of the Tiwi geothermal field, Philippines, based on continuous and spot core measurements

Petrologic analyses of corehole Mat-25 provide a detailed look at the influence of lithology, depth of burial, temperature and hydrothermal fluid chemistry on matrix porosity and permeability in a geothermal system. Average porosity values decline from about 10% at the top of the reservoir to 2.5% at the bottom. A similar trend of declining porosity with depth is observed in spot cores from other wells. The trend of declining porosity with depth is ascribed mainly to increasing overburden stresses and chemical reaction with hydrothermal fluids. Local variations in porosity are a complex function of sample-to-sample variations in the original texture, phenocryst abundance, and amount of glass in the primary rocks, and their exposure to tectonic and hydrothermal processes. Matrix permeability mimics porosity, but is very low within the reservoir section (<10 microdarcy), and even lower above and below the reservoir (<1 microdarcy) in Mat-25. Image analysis indicates that pores >1 μm form mainly by dissolution and partial replacement of plagioclase phenocrysts in the andesitic reservoir rocks, with calcic plagioclase being most susceptible. This relationship between hydrothermal alteration and pore formation may link these larger pores to fracture permeability. The size of the pores can be enhanced by further dissolution of the plagioclase and other minerals or sealed by illite, which is supersaturated in the present-day reservoir fluid.

Calcium sprays, time of harvest, and duration in cold storage affects fruit quality of d'Anjou pears in a critical year

Calcium chloride (CaCl2) sprays increased calcium (Ca) concentrations in d'Anjou fruit (Pyrus communis L.), reduced the incidence of cork spot and improved shelf‐life by increasing fruit firmness in a critical year that had lower fruit Ca concentrations due to record high spring and late season temperatures. The third and final harvest in late September resulted in larger fruit size, lower fruit Ca concentrations, higher incidence of cork spot, more extractable juice and yellow fruit skin color, higher soluble solids and sucrose concentrations, but lower acidity than earlier harvested fruits. Fruit held longer in cold storage (145 days) had higher concentrations of fruit Ca, lower concentrations of carbon dioxide (CO2) and ethylene (C2H4), less fruit firmness, soluble solids and acidity, lower concentrations of sucrose, glucose and fructose, and less green color of fruit skin than short term storage (45 days). Shelf‐life of CaCl2‐sprayed fruit was improved because of higher concentrations of fruit Ca that resulted in a lower incidence of cork spot and brown core, fruit firmness was higher, levels of CO2 and C2H4 were lower, and soluble solids, acidity, and extractable juices were affected less for ripened fruit.

Fracture systematics in and around well WD-1, kakkonda geothermal field, japan

Interpretation of FMI (Schlumbergers Fullbore Formation MicroImager) logs from well WD-1 and observation of spot cores from well WD-1 in the Kakkonda geothermal field have provided important clues about the nature and configuration of the fracture networks controlling circulation of high-temperature hydrothermal fluid. The fractures comprise four groups: (1) fractures striking NW, (2) high-angle fractures striking NE to E, (3) low-angle fractures striking N, and (4) low-angle fractures striking E. Most permeable fractures in the shallow (<1500 m depth) and deep reservoirs are of group 3, and likely reflect reverse faulting in the modern stress field. Low-angle, group 4 fractures are also permeable, and may have formed in the stress field that existed prior to 0.2±0.1 Ma. Distributions and densities of fractures are comparable in the shallow and deep reservoirs; the temperature difference between the reservoirs is independent of these variables.

High-resolution 3D seismic reflection and coring techniques applied to late Quaternary deposits on the New Jersey shelf

Studies of variable, small-scale features typical of Quaternary glacimarine environments require an interdisciplinary approach: precisely navigated, high-resolution 3D seismic surveys nested within a regional 2D seismic framework and integrated with a precisely navigated coring program designed to sample specific shallow acoustic facies. We illustrate this approach with examples from continuing studies of sediments on the New Jersey continental shelf. Surficial stratigraphy associated with the latest Pleistocene-Holocene deglaciation has been imaged twice in true 3D using the Huntec® DTS system, a deep-towed, high-frequency (500–3500 Hz) boomer source. In both cases, nominal profile spacing was 10 m (2.5 m shot points). Penetration of ~40 ms (~30 m) was achieved. Seismic facies in the upper 5 m have been interpreted using differential GPS-navigated vibra-cores. Accuracy of position of both seismic profiles and core locations approaches 5 m, much smaller than the wavelengths of the geologic features being imaged/sampled. Survey results show multiple, sediment-filled channels buried beneath the modern outer shelf meandering south and southeast, in the general direction of the shelf edge. Channels are typically a few meters deep and 100–200 m across. Lateral continuity between the channeled surfaces within the outer-shelf wedge and the mid-shelf cannot be demonstrated because of later erosion, but both sets of channels incise reflector ‘R’, believed to be a pre-Late Wisconsinan exposure surface. AMS 14C dates on benthic foraminifers from cores show that channels on the midshelf are cut into sediment >45,000 yrs old, and filled with muddy sediment as young as ~12,500 yrs, whereas channels on the outer shelf are filled with coarser, and perhaps older, sediment. Both sets of filled channels are buried beneath a surficial sand layer. The integrated approach described here can remove some uncertainties and considerably ‘sharpen’ the Quaternary stratigraphic picture. Without the perspective obtained from 3D seismic surveys and equally precise sampling, interpretations based on broader regional seismic surveys and spot coring are inevitably constrained by the potential for mismatching shallow acoustic and sedimentary facies.