Journal articles: 'Direct in situ high-pressure preconcentration'

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Lecharlier, Aurore, Hervé Carrier, Brice Bouyssiere, Guilhem Caumette, Pierre Chiquet, and Isabelle Le Hécho. "Novel field-portable high-pressure adsorbent tube sampler prototype for the direct in situ preconcentration of trace compounds in gases at their working pressures: application to biomethane." RSC Advances 12, no. 16 (2022): 10071–87. http://dx.doi.org/10.1039/d2ra00601d.

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Claflin, Megan S., Demetrios Pagonis, Zachary Finewax, Anne V. Handschy, Douglas A. Day, Wyatt L. Brown, John T. Jayne, et al. "An in situ gas chromatograph with automatic detector switching between PTR- and EI-TOF-MS: isomer-resolved measurements of indoor air." Atmospheric Measurement Techniques 14, no. 1 (January 7, 2021): 133–52. http://dx.doi.org/10.5194/amt-14-133-2021.

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Abstract. We have developed a field-deployable gas chromatograph (GC) with thermal desorption preconcentration (TDPC), which is demonstrated here with automatic detector switching between two high-resolution time-of-flight mass spectrometers (TOF-MSs) for in situ measurements of volatile organic compounds (VOCs). This system provides many analytical advances, including acquisition of fast time–response data in tandem with molecular speciation and two types of mass spectral information for each resolved GC peak: molecular ion identification from Vocus proton transfer reaction (PTR) TOF-MS and fragmentation pattern from electron ionization (EI) TOF-MS detection. This system was deployed during the 2018 ATHLETIC campaign at the University of Colorado Dal Ward Athletic Center in Boulder, Colorado, where it was used to characterize VOC emissions in the indoor environment. The addition of the TDPC-GC increased the Vocus sensitivity by a factor of 50 due to preconcentration over a 6 min GC sample time versus direct air sampling with the Vocus, which was operated with a time resolution of 1 Hz. The GC-TOF methods demonstrated average limits of detection of 1.6 ppt across a range of monoterpenes and aromatics. Here, we describe the method to use the two-detector system to conclusively identify a range of VOCs including hydrocarbons, oxygenates, and halocarbons, along with detailed results including the quantification of anthropogenic monoterpenes, where limonene accounted for 47 %–80 % of the indoor monoterpene composition. We also report the detection of dimethylsilanediol (DMSD), an organosiloxane degradation product, which was observed with dynamic temporal behavior distinct from volatile organosiloxanes (e.g., decamethylcyclopentasiloxane, D5 siloxane). Our results suggest DMSD is produced from humidity-dependent heterogeneous reactions occurring on surfaces in the indoor environment, rather than formed through gas-phase oxidation of volatile siloxanes.

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Mohn, J., C. Guggenheim, B. Tuzson, M. K. Vollmer, and L. Emmenegger. "A liquid nitrogen-free preconcentration unit for measurements of ambient N<sub>2</sub>O isotopomers by QCLAS." Atmospheric Measurement Techniques Discussions 2, no. 6 (December 4, 2009): 3099–126. http://dx.doi.org/10.5194/amtd-2-3099-2009.

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Abstract. Important information about the biogeochemical cycle of nitrous oxide (N2O) can be obtained by measuring its three main isotopomers, 14N15N16O, 15N14N16O, and 14N14N16O, and the respective site-specific isotope ratios δ15Nα and δ15Nβ. Absorption laser spectroscopy in the mid-infrared is a direct method for N2O isotopomer analysis, yet not sensitive enough for atmospheric N2O concentrations (320 ppb). To enable a fully-automated high precision N2O isotopomer analysis at ambient concentrations, we built and optimized a liquid nitrogen-free preconcentration unit to be coupled to a quantum cascade laser (QCL) based spectrometer. Rigorous tests were conducted, using FTIR and quantum cascade laser absorption spectroscopy (QCLAS), to investigate recovery rates, conservation of isotopic signatures and spectral interferences after preconcentration. We achieve quantitative N2O recovery of >99% with only minor, statistically not significant isotopic fractionation and no relevant spectral interferences from other atmospheric constituents. The developed preconcentration unit also has the potential to be applied to other trace gases and their isotopic composition.

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Humphries, Terry D., Derek Birkmire, Bjørn C. Hauback, G. Sean McGrady, and Craig M. Jensen. "In situ high pressure NMR study of the direct synthesis of LiAlH4." Journal of Materials Chemistry A 1, no. 9 (2013): 2974. http://dx.doi.org/10.1039/c3ta10239d.

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Humphries, Terry D., Derek Birkmire, Bjørn C. Hauback, G. Sean McGrady, and Craig M. Jensen. "In situ high pressure NMR study of the direct synthesis of NaAlH4." Physical Chemistry Chemical Physics 15, no. 17 (2013): 6179. http://dx.doi.org/10.1039/c3cp50777g.

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Mohn, J., C. Guggenheim, B. Tuzson, M. K. Vollmer, S. Toyoda, N. Yoshida, and L. Emmenegger. "A liquid nitrogen-free preconcentration unit for measurements of ambient N<sub>2</sub>O isotopomers by QCLAS." Atmospheric Measurement Techniques 3, no. 3 (May 12, 2010): 609–18. http://dx.doi.org/10.5194/amt-3-609-2010.

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Abstract. Important information about the biogeochemical cycle of nitrous oxide (N2O) can be obtained by measuring its three main isotopic species, 14N15N16O, 15N14N16O, and 14N14N16O, and the respective site-specific relative isotope ratio differences δ15Nα and δ15Nβ. Absorption laser spectroscopy in the mid-infrared is a direct method for the analysis of the 15N isotopic composition of N2O, yet not sensitive enough for atmospheric N2O mixing ratios (320 ppb). To enable a fully-automated high precision analysis of N2O isotopic species at ambient mixing ratios, we built and optimized a liquid nitrogen-free preconcentration unit to be coupled to a quantum cascade laser (QCL) based spectrometer. During standard operation 10 l of ambient air are preconcentrated on a HayeSep D trap and desorbed in 50 ml of synthetic air. Rigorous tests were conducted, using FTIR, quantum cascade laser absorption spectroscopy (QCLAS), GC-FID and component-specific ozone and oxygen analysers to investigate recovery rates, conservation of isotopic signatures and spectral interferences after preconcentration. We achieve quantitative N2O recovery of >99% with only minor, statistically not significant isotopic fractionation and no relevant spectral interferences from other atmospheric constituents. The developed preconcentration unit also has the potential to be applied to other trace gases and their isotopic composition.

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Krogh Andersen, Anne Marie, and Stefan Carlson. "High-pressure structures of α- and δ-ZrMo2O8." Acta Crystallographica Section B Structural Science 57, no. 1 (February 1, 2001): 20–26. http://dx.doi.org/10.1107/s0108768100013215.

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In situ high-pressure synchrotron X-ray powder diffraction studies of trigonal α-ZrMo2O8, zirconium molybdate, have been performed from ambient conditions to 1.9 GPa, over the α–δ phase transition at 1.06–1.11 GPa. The monoclinic structure of δ-ZrMo2O8, stable between 1.1 and 2.5 GPa at 298 K, has been solved by direct methods and refined using the Rietveld method. Significant distortions of the ZrO6 and MoO4 polyhedral elements are observed for δ-ZrMo2O8, as compared to the ambient conditions of the α-phase, while the packing of anions becomes more symmetric at high pressure.

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Kakurina, Maria, Yves Guglielmi, Christophe Nussbaum, and Benoît Valley. "In Situ Direct Displacement Information on Fault Reactivation During Fluid Injection." Rock Mechanics and Rock Engineering 53, no. 10 (August 10, 2020): 4313–28. http://dx.doi.org/10.1007/s00603-020-02160-w.

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Abstract The three dimensional (3D) displacement induced by fluid injection was measured during two fault reactivation experiments conducted in carbonate rocks at the Rustrel Low Noise Underground Laboratory (LSBB URL), France, and in shale rocks at the Mont Terri Rock laboratory, Switzerland. The faults were activated by injecting high pressure fluid and using the Step-Rate Injection Method for Fracture In-Situ Properties, which allows a coupled pressure-flowrate-3D displacement monitoring in boreholes. Both experiments mainly show complex aseismic deformation of preexisting fractures that depend on (1) the fluid pressure variations related to chamber pressurization and leakage into the formation and (2) irreversible shear slip and opening of the reactivated fractures. Here we detail the processing of the 3D displacement data from both experiments to isolate slip vectors from the complex displacement signal. Firstly, we explain the test protocol and describe the in situ hydromechanical behavior of the borehole/fault system. Secondly, we define the methodology of the displacement data processing to isolate slip vectors with high displacement rates, which carry information about the key orientation of fault reactivation. Finally, we discuss which slip vectors can potentially be used to solve the stress inversion problem.

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Hoffman, Adam S., Joseph A. Singh, Stacey F. Bent, and Simon R. Bare. "In situ observation of phase changes of a silica-supported cobalt catalyst for the Fischer–Tropsch process by the development of a synchrotron-compatible in situ/operando powder X-ray diffraction cell." Journal of Synchrotron Radiation 25, no. 6 (October 26, 2018): 1673–82. http://dx.doi.org/10.1107/s1600577518013942.

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In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer–Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer–Tropsch catalysis using syngas, H2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

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Ivanova, E., G. Schaldach, and H. Berndt. "Hydraulic high-pressure nebulization sample introduction for direct analysis or on-line matrix separation and trace preconcentration in flame AAS." Fresenius' Journal of Analytical Chemistry 342, no. 1-2 (1992): 47–50. http://dx.doi.org/10.1007/bf00321688.

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Storey, Benjamin M., Richard H. Worden, and David D. McNamara. "The Geoscience of In-Situ Combustion and High-Pressure Air Injection." Geosciences 12, no. 9 (September 13, 2022): 340. http://dx.doi.org/10.3390/geosciences12090340.

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Considering the global drive toward net-zero carbon emissions in the near future, the need to find clean sources of energy has never been more important. It is estimated that globally there are tens of thousands of depleted and abandoned oil fields that may be adapted to produce green energy. These may be re-cycled with the help of air injection, either from the production of hydrogen, as a direct result of oxidation of oil, or the exploitation of the inherent increase in heat flow and pressure via enhanced geothermal systems. In the past, the use of in-situ combustion (ISC) and high-pressure air injection (HPAI) have experienced many failures, largely due to poor project design and inappropriate reservoir selection. Here, we review data from field applications, experimental studies, and numerical modelling to define the roles of sub-surface sedimentology and petrophysics, structural geology, geomechanics, mineralogy, diagenesis, and petroleum geology on the success of ISC and HPAI. We show how current knowledge can help mitigate project failure via improved project design and initial reservoir selection. Improvements to the design and implementation of ISC and HPAI projects promise to allow the utilisation of the many abandoned oil fields, to produce green energy with the added benefit of the cost-effective, and materials and energy efficient, re-use of existing oil field infrastructure. We conclude that the integration of field data, laboratory experiments, and numerical modelling methods previously studied can be used to help develop ISC and minimize risk of failure.

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Wang, Ding-Ming, Ling Chen, Da Guo, Zhi-Qiang Liu, Ju Li, Xun Yang, and Yi-Wei Zhang. "Discrete element analysis on the influence of drilling fluid pressure on core discing in pressure-preserved coring." Thermal Science 27, no. 1 Part B (2023): 655–65. http://dx.doi.org/10.2298/tsci2301655w.

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In the process of coring in a high in-situ stress environment, the rock core is damaged due to stress release, and core discing is a prominent manifestation of this damage. Pressure-preserved coring has no direct effect on in-situ stress, and its influence on stress release is related to drilling fluid pressure. Yet fluid pressure in the coring process was not considered in most former numerical simulation studies on core discing. In this paper, the discrete element method software PFC3D is used to conduct a numerical simulation of the coring process. According to the two conditions without drilling fluid pressure and with it, and different horizontal in-situ stresses of 5-160 MPa, fracture and discing of the core with drilling are observed. In addition, the law of fracture and discing in the process of coring was studied, and the function of pressure-preserved coring to prevent fracture and discing is explored. Simulation results show nonlinear trends in distribution of discs both in time and in space.

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Ono, S. "High-pressure phase transformation in MnCO3: a synchrotron XRD study." Mineralogical Magazine 71, no. 1 (February 2006): 105–11. http://dx.doi.org/10.1180/minmag.2007.071.1.105.

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AbstractThe high-pressure behaviour of manganese carbonate was investigated by in situ synchrotron X-ray powder diffraction up to 54 GPa with a laser-heated diamond anvil cell. A phase transition from rhodochrosite to a new structure form was observed at 50 GPa after laser heating. The diffraction pattern of the new high-pressure form was reasonably indexed with an orthorhombic unit-cell with a = 5.361 A, b = 8.591 A and c = 9.743 Å. The pressure-induced phase transition implies a unit-cell volume reduction of ∼5%. This result does not support the direct formation of diamond by dissociation of solid state MnCO3 reported in a previous study. Fitting the compression data of rhodochrosite to a second-order Birch-Murnaghan equation of state (Ko’ = 4) gives K0 = 126(±10) GPa. The c axis of the unit-cell parameter was more compressive than the a axis.

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Brown, S. Brennan, A. E. Gleason, E. Galtier, A. Higginbotham, B. Arnold, A. Fry, E. Granados, et al. "Direct imaging of ultrafast lattice dynamics." Science Advances 5, no. 3 (March 2019): eaau8044. http://dx.doi.org/10.1126/sciadv.aau8044.

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Under rapid high-temperature, high-pressure loading, lattices exhibit complex elastic-inelastic responses. The dynamics of these responses are challenging to measure experimentally because of high sample density and extremely small relevant spatial and temporal scales. Here, we use an x-ray free-electron laser providing simultaneous in situ direct imaging and x-ray diffraction to spatially resolve lattice dynamics of silicon under high–strain rate conditions. We present the first imaging of a new intermediate elastic feature modulating compression along the axis of applied stress, and we identify the structure, compression, and density behind each observed wave. The ultrafast probe x-rays enabled time-resolved characterization of the intermediate elastic feature, which is leveraged to constrain kinetic inhibition of the phase transformation between 2 and 4 ns. These results not only address long-standing questions about the response of silicon under extreme environments but also demonstrate the potential for ultrafast direct measurements to illuminate new lattice dynamics.

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Geilfus, N. X., B. Delille, V. Verbeke, and J. L. Tison. "Towards a method for high vertical resolution measurements of the partial pressure of CO2 within bulk sea ice." Journal of Glaciology 58, no. 208 (2012): 287–300. http://dx.doi.org/10.3189/2012jog11j071.

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AbstractFluxes of atmospheric CO2 have been reported over sea ice during winter and spring. These fluxes are partly driven by the gradient of the CO2 concentration between sea ice and the atmosphere. We present a new non-destructive method to measure the pCO2 of bulk sea ice at its in situ temperature. This method is based on an equilibration procedure between sea ice and a standard gas of known CO2 concentration. The concentration is measured by gas chromatography with a precision of 5%. Tests were performed on artificial standard sea ice and confirmed the reproducibility of the technique in the range of precision of the gas chromatograph. To test the accuracy of this method, the first profiles of pCO2 measured in bulk sea ice are reported and compared with direct in situ measurements of brine pCO2 over depth-integrated intervals.

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Adibah, Nurulain A., S. N. Azella, and M. F. Abd Shukur. "Synthesis of Ti₃C₂ Mxene through In Situ HF and Direct HF Etching Procedures as Electrolyte Fillers in Dye-Sensitized Solar Cell." Materials Science Forum 1023 (March 2021): 15–20. http://dx.doi.org/10.4028/www.scientific.net/msf.1023.15.

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MXene is the new family of two-dimensional (2D) transition metal carbides, carbonitrides and nitrides discovered in 2011. The unique properties of 2D MXene such as excellent mechanical properties, hydrophilic surfaces and metallic conductivity made it interesting for application in electrodes of rechargeable batteries, supercapacitors, photocatalysts, catalysts, transparent conducting films, and flexible high-strength composites. The MXene can be synthesized through a selective etching process by using either in-situ HF (hydrofluoric acid) or direct HF methods. This study reports on the effect of the in-situ HF and direct HF etching procedures on the morphology of the synthesis Ti2C3 MXene using titanium aluminum carbide (Ti2AlC3) as precursor. The morphology and elements presence were evaluated by using variable pressure field emission scanning electron microscope (FESEM) and energy dispersion X-ray (EDX) spectroscopy analyses, respectively. The analysis shows that the MXene synthesized through the direct HF method was successfully delaminated compared to the in-situ HF procedures.

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Giomataris, I., S. Green, I. Katsioulas, P. Knights, I. Manthos, J. Matthews, T. Neep, et al. "Neutron spectroscopy with N₂-filled high-pressure large-volume spherical proportional counters." Journal of Physics: Conference Series 2374, no. 1 (November 1, 2022): 012144. http://dx.doi.org/10.1088/1742-6596/2374/1/012144.

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Precise in-situ measurements of the neutron flux in underground laboratories is crucial for direct dark matter searches, as neutron induced backgrounds can mimic the typical dark matter signal. The development of a novel neutron spectroscopy technique using Spherical Proportional Counters is investigated. The detector is operated with nitrogen and is sensitive to both fast and thermal neutrons through the 14N(n, α)11B and 14N(n, p)14C reactions. This method holds potential to be a safe, inexpensive, effective, and reliable alternative to 3He-based detectors. Measurements of fast and thermal neutrons from an Am-Be source with a Spherical Proportional Counter operated at pressures up to 2 bar at Birmingham are discussed.

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Zhong, Xin, Arianne J. Petley-Ragan, Sarah H. M. Incel, Marcin Dabrowski, Niels H. Andersen, and Bjørn Jamtveit. "Lower crustal earthquake associated with highly pressurized frictional melts." Nature Geoscience 14, no. 7 (June 17, 2021): 519–25. http://dx.doi.org/10.1038/s41561-021-00760-x.

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AbstractEarthquakes at lower crustal depths are common during continental collision. However, the coseismic weakening mechanisms required to propagate an earthquake at high pressures are poorly understood. Transient high-pressure fluids or melts have been proposed as a viable mechanism, but verifying this requires direct in situ measurement of fluid or melt overpressure along fault planes that have hosted dynamic ruptures. Here, we report direct measurement of highly overpressurized frictional melts along a seismic fault surface. Using Raman spectroscopy, we identified high-pressure quartz inclusions sealed in dendritic garnets that grew from frictional melts formed by lower crustal earthquakes in the Bergen Arcs, Western Norway. Melt pressure was estimated to be 1.8–2.3 GPa on the basis of an elastic model for the quartz-in-garnet system. This is ~0.5 GPa higher than the pressure recorded by the surrounding pseudotachylyte matrix and wall rocks. The recorded melt pressure could not arise solely from the volume expansion of melting, and we propose that it was generated when melt pressure approached the maximum principal stress in a system subject to high differential stress. The associated palaeostress field demonstrates that a strong lower crust accommodated up to 1 GPa differential stress during the compressive stage of the Caledonian orogeny.

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COOPER∗, CLAYTON S., and NORMAND M. LAURENDEAU. "In-Situ Calibration Technique for Laser-Induced Fluorescence Measurements of Nitric Oxide in High-Pressure, Direct-Injection, Swirling Spray Flames." Combustion Science and Technology 161, no. 1 (December 2000): 165–89. http://dx.doi.org/10.1080/00102200008935816.

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Zhang, Rui Yong, Sabrina Hedrich, and Axel Schippers. "Reduction of Iron(III) Ions at Elevated Pressure by Acidophilic Microorganisms." Solid State Phenomena 262 (August 2017): 88–92. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.88.

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A composed mixed acidophilic, iron-oxidizing culture (FIGB) and a thermo-acidophilic enrichment culture (TK65) were used to evaluate microbial iron(III) reduction coupled to oxidation of reduced inorganic sulfur compounds (RISCs) under high pressure. Experiments were done in batch culture in high pressure vessels at 1 and 100 bar. Microbial abundance and activity were determined by measuring iron(II) concentration, direct cell counting, T-RFLP and quantitative real-time PCR. The data indicate that both cultures are able to reduce soluble iron(III) by oxidation of sulfur compounds under anaerobic conditions. At high pressure (100 bar) these acidophiles were capable of growing and microbial ferric iron reduction was only partially inhibited. These results indicate that acidophiles can be barotolerant and their activities are contributing to sulfur and iron cycling in anaerobic environments including deep ore deposits which is highly relevant for in situ leaching operations.

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Lutyński, Marcin, Jan Kielar, Dawid Gajda, Marcel Mikeska, and Jan Najser. "High-Pressure Adsorption of CO2 and CH4 on Biochar—A Cost-Effective Sorbent for In Situ Applications." Materials 16, no. 3 (February 2, 2023): 1266. http://dx.doi.org/10.3390/ma16031266.

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The search for an effective, cost-efficient, and selective sorbent for CO2 capture technologies has been a focus of research in recent years. Many technologies allow efficient separation of CO2 from industrial gases; however, most of them (particularly amine absorption) are very energy-intensive processes not only from the point of view of operation but also solvent production. The aim of this study was to determine CO2 and CH4 sorption capacity of pyrolyzed spruce wood under a wide range of pressures for application as an effective adsorbent for gas separation technology such as Pressure Swing Adsorption (PSA) or Temperature Swing Adsorption (TSA). The idea behind this study was to reduce the carbon footprint related to the transport and manufacturing of sorbent for the separation unit by replacing it with a material that is the direct product of pyrolysis. The results show that pyrolyzed spruce wood has a considerable sorption capacity and selectivity towards CO2 and CH4. Excess sorption capacity reached 1.4 mmol·g−1 for methane and 2.4 mmol·g−1 for carbon dioxide. The calculated absolute sorption capacity was 1.75 mmol·g−1 at 12.6 MPa for methane and 2.7 mmol·g−1 at 4.7 Mpa for carbon dioxide. The isotherms follow I type isotherm which is typical for microporous adsorbents.

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Kuebler, Wolfgang M., Xiaoyou Ying, and Jahar Bhattacharya. "Pressure-induced endothelial Ca2+ oscillations in lung capillaries." American Journal of Physiology-Lung Cellular and Molecular Physiology 282, no. 5 (May 1, 2002): L917—L923. http://dx.doi.org/10.1152/ajplung.00275.2001.

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Endothelial second messenger responses may contribute to the pathology of high vascular pressure but remain poorly understood because of the lack of direct in situ quantification. In lung venular capillaries, we determined endothelial cytosolic Ca2+ concentration [Ca2+]i by the fura 2 ratioing method. Pressure elevation increased mean endothelial [Ca2+]i by Ca2+ influx through gadolinium-inhibitable channels and amplified [Ca2+]i oscillations by Ca2+release from intracellular stores. Endothelial [Ca2+]i transients were induced by pressure elevations of as little as 5 cmH2O and increased linearly with higher pressures. Heptanol inhibition of [Ca2+]i oscillations in a subset of endothelial cells indicated that oscillations originated from pacemaker endothelial cells and were propagated to adjacent nonpacemaker cells by gap junctional communication. Our findings indicate the presence of a sensitive, active endothelial response to pressure challenge in lung venular capillaries that may be relevant in the pathogenesis of pressure-induced lung microvascular injury.

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Shi, Runfeng, Jiankang Zhang, Jinheng Yang, Yanglei Xu, Cuihuan Li, Sheng Chen, and Feng Xu. "Direct-Ink-Write Printing and Electrospinning of Cellulose Derivatives for Conductive Composite Materials." Materials 15, no. 8 (April 13, 2022): 2840. http://dx.doi.org/10.3390/ma15082840.

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The aim of this study is to realize the controlled construction and modulation of micro-/nanostructures of conductive composite materials (CCMs) in a facile way. Herein, interdigital electrodes are prepared by direct-ink-write printing co-blended inks made of ethyl cellulose and carbon nanotubes on cellulose paper. The cellulose nanofibers (CFs) are prepared by electrospinning cellulose acetate on to an aluminum foil, followed by deacetylation in NaOH/ethanol. All co-blended inks exhibit a typical non-Newtonian shear thinning behavior, enabling smooth extrusion and printing. The above electrodes and the conductive CF films with excellent thermal stability are assembled into a pressure sensor, which has a high sensitivity (0.0584 KPa−1) to detect the change in external loading pressure. The obtained porous CFs film is further endowed with conductivity by in situ polymerization of polypyrrole (PPy), which are uniformly distributed on the CFs surface as particles; a triboelectric nanogenerator is constructed by using the CF@PPy film as a tribo-positive friction layer to achieve efficient energy harvesting (output voltage = 29.78 V, output current = 2.12 μA). Therefore, the construction of CCMs with micro-/nanostructures based on cellulose derivatives have essential application prospects in emerging high-tech fields, such as green electronics for sensing and energy harvesting.

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Wiśniewska, Marta, and Mirosław Szyłak-Szydłowski. "The Application of In Situ Methods to Monitor VOC Concentrations in Urban Areas—A Bibliometric Analysis and Measuring Solution Review." Sustainability 14, no. 14 (July 19, 2022): 8815. http://dx.doi.org/10.3390/su14148815.

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Urbanisation development affects urban vegetation both directly and indirectly. Since this process usually involves a dramatic change in land use, it is seen as likely to cause ecological pressure on local ecosystems. All forms of human activity, including urbanisation of areas close to residential buildings, significantly impact air quality. This study aims to identify and characterise different measurement solutions of VOCs, allowing the quantification of total and selective compounds in a direct at source (in situ) manner. Portable devices for direct testing can generally be divided into detectors, chromatographs, and electronic noses. They differ in parameters such as operating principle, sensitivity, measurement range, response time, and selectivity. Direct research allows us to obtain measurement results in a short time, which is essential from the point of view of immediate reaction in the case of high concentrations of tested compounds and the possibility of ensuring the well-being of people. The paper also attempts to compare solutions and devices available on the market and assess their application.

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Wang, Xiaojia, Xianli Liu, Baosheng Jin, and Decheng Wang. "Hydrodynamic Study of AR Coupling Effects on Solid Circulation and Gas Leakages in a High-Flux In Situ Gasification Chemical Looping Combustion System." Processes 6, no. 10 (October 18, 2018): 196. http://dx.doi.org/10.3390/pr6100196.

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In situ gasification chemical looping combustion (iG-CLC) is a novel and promising coal combustion technology with inherent separation of CO2. Our previous studies demonstrated the feasibility of performing iG-CLC with a high-flux circulating fluidized bed (HFCFB) riser as the fuel reactor (FR) and a counter-flow moving bed (CFMB) as the air reactor (AR). As an extension of that work, this study aims to further investigate the fundamental effects of the AR coupling on the oxygen carrier (OC) circulation and gas leakages with a cold-state experimental device of the proposed iG-CLC system. The system exhibited favorable pressure distribution characteristics and good adaptability of solid circulation flux, demonstrating the positive role of the direct coupling method of the AR in the stabilization and controllability of the whole system. The OC circulation and the gas leakages were mainly determined by the upper and lower pressure gradients of the AR. With the increase in the upper pressure gradient, the OC circulation flux increased initially and later decreased until the circulation collapsed. Besides, the upper pressure gradient exhibited a positive effect on the restraint of gas leakage from the FR to the AR, but a negative effect on the suppression of gas leakage from the AR to the FR. Moreover, the gas leakage of the J-valve to the AR, which is directly related to the solid circulation stability, was exacerbated with the increase of the lower pressure gradient of the AR. In real iG-CLC applications, the pressure gradients should be adjusted flexibly and optimally to guarantee a balanced OC circulation together with an ideal balance of all the gas leakages.

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Xu, Man, Zhicheng Jing, Suraj K. Bajgain, Mainak Mookherjee, James A. Van Orman, Tony Yu, and Yanbin Wang. "High-pressure elastic properties of dolomite melt supporting carbonate-induced melting in deep upper mantle." Proceedings of the National Academy of Sciences 117, no. 31 (July 20, 2020): 18285–91. http://dx.doi.org/10.1073/pnas.2004347117.

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Deeply subducted carbonates likely cause low-degree melting of the upper mantle and thus play an important role in the deep carbon cycle. However, direct seismic detection of carbonate-induced partial melts in the Earth’s interior is hindered by our poor knowledge on the elastic properties of carbonate melts. Here we report the first experimentally determined sound velocity and density data on dolomite melt up to 5.9 GPa and 2046 K by in-situ ultrasonic and sink-float techniques, respectively, as well as first-principles molecular dynamics simulations of dolomite melt up to 16 GPa and 3000 K. Using our new elasticity data, the calculated VP/VSratio of the deep upper mantle (∼180–330 km) with a small amount of carbonate-rich melt provides a natural explanation for the elevated VP/VSratio of the upper mantle from global seismic observations, supporting the pervasive presence of a low-degree carbonate-rich partial melt (∼0.05%) that is consistent with the volatile-induced or redox-regulated initial melting in the upper mantle as argued by petrologic studies. This carbonate-rich partial melt region implies a global average carbon (C) concentration of 80–140 ppm. by weight in the deep upper mantle source region, consistent with the mantle carbon content determined from geochemical studies.

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Han, Dongmei, Yong Chen, Shuanjin Wang, Min Xiao, Yixin Lu, and Yuezhong Meng. "Effect of In-Situ Dehydration on Activity and Stability of Cu–Ni–K2O/Diatomite as Catalyst for Direct Synthesis of Dimethyl Carbonate." Catalysts 8, no. 9 (August 23, 2018): 343. http://dx.doi.org/10.3390/catal8090343.

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An in-situ dehydrating system built in a continuous flow fixed-bed bubbling reactor for direct synthesis of dimethyl carbonate (DMC) was designed. 3A molecular sieve (MS) was selected as the ideal dehydrating agent and the water trapping efficiency was studied. The effect of dehydrating agent/catalyst ratio, the dehydrating temperature and pressure, as well as the space velocity on the direct DMC synthesis catalyzed by K2O-promoted Cu–Ni was further investigated. These results demonstrated that 3A MS could effectively dehydrate the reaction system at the optimal conditions of 120 °C and 1.0 MPa with gas space velocity (GHSV) of 600 h−1, thereby greatly shifting the reaction equilibrium toward high DMC yield. Higher DMC yield of 13% was achieved compared with undehydrated reaction. Moreover, the catalyst can be highly stabilized by 3A MS dehydration with stable performs over 22 h.

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Shimizu, Kobayashi, Vorholt, and Yang. "Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming." Metals 9, no. 9 (August 22, 2019): 917. http://dx.doi.org/10.3390/met9090917.

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: To investigate the underlying mechanism of the effects of surface texturing on lubricated sliding friction in the metal forming operation, an in-situ observation system using transparent silica glass dies and a high speed recording camera was newly developed. To correlate the dimensional parameters of micro-dimple textured structures and tribological properties in the metal forming operation, the in-situ observation was performed during bending with the ironing process of the stainless steel sheet with a thickness of 0.1 mm. The lubrication behavior were compared between the different lubricant viscosities and the micro-dimple textures with different diameters of 10 µm, 50 µm, 100 µm fabricated by using femto-/pico-second laser processing. As a result, the textured die with dimple diameters of 10 µm and 50 µm showed the lubricant flow transferred from one to the other dimples owing to the lubricant reservoir effect, while that of 100 µm indicated the less supply of the lubricant. However, the textured die with a dimple diameter of 10 µm demonstrated higher ironing force than that of 50 µm, due to the severe adhesion of work materials inside the dimple structures. Based on these experimental findings, the dimple size dependencies on lubricant reservoirs effects and the generation of the hydrodynamic pressure were discussed by correlating with the in-situ observation results, a fluid-flow analysis and a laminar two-phase flow analysis using the finite element method.

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29

Randolph, Brian W., Edward P. Steinhauser, Andrew G. Heydinger, and Jiwan D. Gupta. "In Situ Test for Hydraulic Conductivity of Drainable Bases." Transportation Research Record: Journal of the Transportation Research Board 1519, no. 1 (January 1996): 36–40. http://dx.doi.org/10.1177/0361198196151900105.

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The development and use of an in situ hydraulic conductivity test for drainable bases under existing pavements is presented. Six highway test sections were constructed by the Ohio Department of Transportation to test the drainage characteristics and durability of four unbound and two stabilized base materials. The in situ test was then used to determine the field hydraulic conductivity of the highway test section bases. This test uses an approach to Darcy's law called the direct velocity technique. A standpipe is placed in a cored hole in the pavement to establish steady-state horizontal flow through the base toward the edge drains. Two probes along a radial flow line measure differential pressure and electrical resistance in the water. An electrolytic solution injected at the standpipe is used to determine the water velocity as the median resistance is noted at each probe. The in situ hydraulic conductivity is calculated by dividing the discharge velocity by the hydraulic gradient. The in situ test provided results that compare favorably with published values from carefully controlled laboratory tests. It proved to work well for high-hydraulic-conductivity drainable bases, and it has the potential to be a valuable tool for condition assessment of bases under existing pavements.

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Liu, Wenlei, Lingli Yu, Xianfeng Cui, Ce Tan, Mengen Zhang, Di Wu, Zhenhuan Li, and Maliang Zhang. "Polyphenylene Sulfide Ultrafine Viscous Fibrous Membrane Modified by ZIF-8 for Highly Effective Oil/Water Separation under High Salt or Alkaline Conditions." Membranes 12, no. 10 (October 20, 2022): 1017. http://dx.doi.org/10.3390/membranes12101017.

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The oil/water separation in harsh environments has always been a challenging topic all over the world. In this study, the ZIF-8/PPS fiber membranes were fabricated via the combination of hot pressing and in situ growth. The distribution of ZIF-8 in the membranes was adjusted by changing the ZIF-8 in situ growth time, which could control the oil/water separation effect. Due to the hydrophilic nature of the ZIF-8/PPS fiber membranes, the water molecules in the oil-in-water emulsion could quickly penetrate into the fiber membrane under the drive of pressure, gravity, and capillary force, forming a water layer on the surface of the fiber membranes. The coupling of the water layer and the fiber structure prevented direct contact between the oil molecules and the fiber membrane, thereby realizing the separation of the emulsion. The results show that when the ZIF-8 in situ growth time was 10 h, the contact angle, the porosity, and the pure water flux of the ZIF-8/PPS fiber membranes were 72.5°, 52.3%, and 12,351 L/h·m2, respectively. More importantly, the separation efficiency of M10 was 97%, and the oil/water separation efficiency reached 95% after 14 cycles. This study provides a novel strategy for preparing MOFs/fiber materials for oil/water separation in harsh environments.

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ARAKAWA, Hironori, Kazuhiko TAKEUCHI, Takehiko MATSUZAKI, and Yoshihiro SUGI. "Direct synthesis of C2-oxygenates from syngas over Co-Re-Sr/SiO2 catalysts. Characterization of catalysts using high pressure in situ FT-IR spectroscopy." Journal of The Japan Petroleum Institute 31, no. 4 (1988): 335–41. http://dx.doi.org/10.1627/jpi1958.31.335.

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32

Zhang, Y. Y., M. X. Tang, Y. Cai, J. C. E, and S. N. Luo. "Deducing density and strength of nanocrystalline Ta and diamond under extreme conditions from X-ray diffraction." Journal of Synchrotron Radiation 26, no. 2 (January 21, 2019): 413–21. http://dx.doi.org/10.1107/s1600577518017216.

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In situ X-ray diffraction with advanced X-ray sources offers unique opportunities for investigating materials properties under extreme conditions such as shock-wave loading. Here, Singh's theory for deducing high-pressure density and strength from two-dimensional (2D) diffraction patterns is rigorously examined with large-scale molecular dynamics simulations of isothermal compression and shock-wave compression. Two representative solids are explored: nanocrystalline Ta and diamond. Analysis of simulated 2D X-ray diffraction patterns is compared against direct molecular dynamics simulation results. Singh's method is highly accurate for density measurement (within 1%) and reasonable for strength measurement (within 10%), and can be used for such measurements on nanocrystalline and polycrystalline solids under extreme conditions (e.g. in the megabar regime).

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33

Salas-Colera, Eduardo, Álvaro Muñoz-Noval, Catherine Heyman, Conchi O. Ania, José B. Parra, Santiago García-Granda, Sofía Calero, Juan Rubio-Zuazo, and Germán R. Castro. "Design and development of a controlled pressure/temperature set-up forin situstudies of solid–gas processes and reactions in a synchrotron X-ray powder diffraction station." Journal of Synchrotron Radiation 22, no. 1 (January 1, 2015): 42–48. http://dx.doi.org/10.1107/s1600577514021018.

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A novel set-up has been designed and used for synchrotron radiation X-ray high-resolution powder diffraction (SR-HRPD) in transmission geometry (spinning capillary) forin situsolid–gas reactions and processes in an isobaric and isothermal environment. The pressure and temperature of the sample are controlled from 10−3to 1000 mbar and from 80 to 1000 K, respectively. To test the capacities of this novel experimental set-up, structure deformation in the porous material zeolitic imidazole framework (ZIF-8) by gas adsorption at cryogenic temperature has been studied under isothermal and isobaric conditions. Direct structure deformations by the adsorption of Ar and N2gases have been observedin situ, demonstrating that this set-up is perfectly suitable for direct structural analysis underin operandoconditions. The presented results prove the feasibility of this novel experimental station for the characterization in real time of solid–gas reactions and other solid–gas processes by SR-HRPD.

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Fedotenko, Timofey, Saiana Khandarkhaeva, Leonid Dubrovinsky, Konstantin Glazyrin, Pavel Sedmak, and Natalia Dubrovinskaia. "Synthesis and Compressibility of Novel Nickel Carbide at Pressures of Earth’s Outer Core." Minerals 11, no. 5 (May 13, 2021): 516. http://dx.doi.org/10.3390/min11050516.

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We report the high-pressure synthesis and the equation of state (EOS) of a novel nickel carbide (Ni3C). It was synthesized in a diamond anvil cell at 184(5) GPa through a direct reaction of a nickel powder with carbon from the diamond anvils upon heating at 3500 (200) K. Ni3C has the cementite-type structure (Pnma space group, a = 4.519(2) Å, b = 5.801(2) Å, c = 4.009(3) Å), which was solved and refined based on in-situ synchrotron single-crystal X-ray diffraction. The pressure-volume data of Ni3C was obtained on decompression at room temperature and fitted to the 3rd order Burch-Murnaghan equation of state with the following parameters: V0 = 147.7(8) Å3, K0 = 157(10) GPa, and K0′ = 7.8(6). Our results contribute to the understanding of the phase composition and properties of Earth’s outer core.

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35

Moser, William R., Joseph R. Berard, Peter J. Melling, and Robert J. Burger. "A New Spectroscopic Technique for in situ Chemical Reaction Monitoring Using Mid-Range Infrared Optical Fibers." Applied Spectroscopy 46, no. 7 (July 1992): 1105–12. http://dx.doi.org/10.1366/0003702924124204.

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A new versatile spectroscopic technique for chemical reaction monitoring using mid-range infrared optical fibers has recently been developed. Chalcogenide glass optical fibers were used to direct infrared radiation from an FT-IR spectrometer through ZnSe Cylindrical Internal Reflectance (CIR) crystals embedded within laboratory scale reactors. The utility of this technique for studying chemical systems was demonstrated by monitoring various stoichiometric reactions at ambient conditions. A laboratory-scale glass reactor fabricated with the capability to mount a CIR crystal was used as the reaction vessel. The ability of this system to monitor high-pressure and/or high-temperature chemical reactions was also demonstrated by studying the cobalt catalyzed hydroformylation of olefins. A stainless steel CIR reactor, slightly modified to allow for connections with optical fibers, was used for experiments ranging from 50 to 90°C and under 750 to 800 psi synthesis gas (H2/CO mixture). In all cases sufficient signal strength at the detector and adequate penetration into the bulk reaction medium was achieved, resulting in infrared spectra of high quality and resolution. Spectral scans of the reaction in progress allowed the accurate determination of the concentration of reactants and products as a function of time.

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36

Schopf, Roland, Nicolas Schork, Estelle Amling, Hermann Nirschl, Gisela Guthausen, and Ulrich Kulozik. "Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis." Membranes 10, no. 4 (March 31, 2020): 59. http://dx.doi.org/10.3390/membranes10040059.

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Milk protein fractionation by microfiltration membranes is an established but still growing field in dairy technology. Even under cross-flow conditions, this filtration process is impaired by the formation of a deposit by the retained protein fraction, mainly casein micelles. Due to deposition formation and consequently increased overall filtration resistance, the mass flow of the smaller whey protein fraction declines within the first few minutes of filtration. Currently, there are only a handful of analytical techniques available for the direct observation of deposit formation with opaque feed media and membranes. Here, we report on the ongoing development of a non-invasive and non-destructive method based on magnetic resonance imaging (MRI), and its application to characterise deposit layer formation during milk protein fractionation in ceramic hollow fibre membranes as a function of filtration pressure and temperature, temporally and spatially resolved. In addition, the chemical composition of the deposit was analysed by reversed phase high pressure liquid chromatography (RP-HPLC). We correlate the structural information gained by in-situ MRI with the protein amount and composition of the deposit layer obtained by RP-HPLC. We show that the combination of in-situ MRI and chemical analysis by RP-HPLC has the potential to allow for a better scientific understanding of the pressure and temperature dependence of deposit layer formation.

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Ferreira, Camilo M., Sean D. Connell, Silvan U. Goldenberg, and Ivan Nagelkerken. "Positive species interactions strengthen in a high-CO 2 ocean." Proceedings of the Royal Society B: Biological Sciences 288, no. 1954 (July 7, 2021): 20210475. http://dx.doi.org/10.1098/rspb.2021.0475.

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Negative interactions among species are a major force shaping natural communities and are predicted to strengthen as climate change intensifies. Similarly, positive interactions are anticipated to intensify and could buffer the consequences of climate-driven disturbances. We used in situ experiments at volcanic CO 2 vents within a temperate rocky reef to show that ocean acidification can drive community reorganization through indirect and direct positive pathways. A keystone species, the algal-farming damselfish Parma alboscapularis, enhanced primary productivity through its weeding of algae whose productivity was also boosted by elevated CO 2 . The accelerated primary productivity was associated with increased densities of primary consumers (herbivorous invertebrates), which indirectly supported increased secondary consumers densities (predatory fish) (i.e. strengthening of bottom-up fuelling). However, this keystone species also reduced predatory fish densities through behavioural interference, releasing invertebrate prey from predation pressure and enabling a further boost in prey densities (i.e. weakening of top-down control). We uncover a novel mechanism where a keystone herbivore mediates bottom-up and top-down processes simultaneously to boost populations of a coexisting herbivore, resulting in altered food web interactions and predator populations under future ocean acidification.

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Md Radzi, Mohamad Razlan, M. Devendran Manogaran, Mohd Hizami Mohd Yusoff, Zulqarnain, Mohd Razealy Anuar, Noor Fazliani Shoparwe, and Mohd Fikri Ab Rahman. "Production of Propanediols through In Situ Glycerol Hydrogenolysis via Aqueous Phase Reforming: A Review." Catalysts 12, no. 9 (August 25, 2022): 945. http://dx.doi.org/10.3390/catal12090945.

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Production of 1,2-propanediol and 1,3-propanediol are identified as methods to reduce glycerol oversupply. Hence, glycerol hydrogenolysis is identified as a thermochemical conversion substitute; however, it requires an expensive, high-pressure pure hydrogen supply. Studies have been performed on other potential thermochemical conversion processes whereby aqueous phase reforming has been identified as an excellent substitute for the conversion process due to its low temperature requirement and high H2 yields, factors which permit the process of in-situ glycerol hydrogenolysis which requires no external H2 supply. Hence, this manuscript emphasizes delving into the possibilities of this concept to produce 1,2-propanediol and 1,3-propanediol without “breaking the bank” with expenses. Various heterogenous catalysts of aqueous phase reforming (APR) and glycerol hydrogenolysis were identified, whereby the combination of a noble metal, support, and dopant with a good amount of Brønsted acid sites are identified as the key factors to ensure a high yield of 1,3-propanediol. However, for 1,2-propanediol, a Cu-based catalyst with decent basic support is observed to be the key for good yield and selectivity of product. The findings have shown that it is possible to produce high yields of both 1,2-propanediol and 1,3-propanediol via aqueous phase reforming, specifically 1,2-propanediol, for which some of the findings achieve better selectivity compared to direct glycerol hydrogenolysis to 1,2-propanediol. This is not the case for 1,3-propanediol, for which further studies need to be conducted to evaluate its feasibility.

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39

Okabe, M., C. Nyakas, B. Buwalda, and P. G. Luiten. "In situ blotting: a novel method for direct transfer of native proteins from sectioned tissue to blotting membrane: procedure and some applications." Journal of Histochemistry & Cytochemistry 41, no. 6 (June 1993): 927–34. http://dx.doi.org/10.1177/41.6.8315283.

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We describe a novel technique for direct transfer of native proteins from unfixed frozen tissues sections to an immobilizing matrix, e.g., nitrocellulose, polyvinyliden difluoride, or positively charged nylon membranes. Proteins are directly blotted onto the membrane, providing optimal accessibility for molecular detection but retaining the anatomic localization at the cellular level. Within 10 min a maximum protein transfer is achieved independent of the protein molecular weight. The total protein bound was 80% of the maximal binding capacity of the blotting membrane and independent of the section thickness. These results indicate that the proteins that bind to the membrane originate from the cut cell monolayer that has direct contact with the blotting membrane. This in situ blotting method provides direct protein mapping from a single cell layer of a tissue section. The procedure includes cryosectioning at 20 microns and collecting sections on a dry blotting membrane at -20 degrees C. For protein transfer the blotted sections are thawed and incubated for 10 min with Tris buffer. After incubation the sections are removed from the membrane by high-pressure spray. The blotted membranes can be subjected to several detection assays. In the present study the presence of several proteins was demonstrated in brain and thymus by immunochemical and enzyme histochemical procedures.

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40

D’Orazio, Dario, Elena Rossi, and Massimo Garai. "Comparison of different in situ measurements techniques of intelligibility in an open-plan office." Building Acoustics 25, no. 2 (June 2018): 111–22. http://dx.doi.org/10.1177/1351010x18776431.

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Acoustic comfort in open-plan offices is a relatively recent research topic and some practices have not yet been consolidated. The goal in these spaces is to achieve good speech privacy at every workstation, reaching a high value of spatial decay of the sound pressure level. In case of refurbishment, a proper measurement of intelligibility criteria is needed, for example, in order to properly calibrate a numerical model or to plan acoustic treatments. This work compares different measurement techniques to evaluate the spatial distribution of intelligibility criteria. In situ measurements were done in an open-plan office used as a case study. Both omnidirectional and directional sound sources with different sound power levels were used, according, respectively, to ISO 3382-3:2012 and ITU-T P.51:1996. Furthermore, compensation algorithms were used in impulse response measurements in presence of Heating, Ventilation and Air Conditioning noise. The study shows, in a preliminary way, how different techniques and equipment can influence intelligibility criteria used in the open-plan office characterization. Results show that the indirect method of measuring Speech Transmission Index could not be used when the background level is high as the case study while the direct method returns good results.

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41

Suchorski, Y., I. Bespalov, J. Zeininger, M. Raab, M. Datler, P. Winkler, and G. Rupprechter. "CO Oxidation on Stepped Rh Surfaces: μm-Scale Versus Nanoscale." Catalysis Letters 150, no. 3 (September 13, 2019): 605–12. http://dx.doi.org/10.1007/s10562-019-02950-0.

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Abstract The catalytic CO oxidation reaction on stepped Rh surfaces in the 10−6 mbar pressure range was studied in situ on individual μm-sized high-Miller-index domains of a polycrystalline Rh foil and on nm-sized facets of a Rh tip, employing photoemission electron microscopy (PEEM) and field-ion/field-emission microscopy (FIM/FEM), respectively. Such approach permits a direct comparison of the reaction kinetics for crystallographically different regions under identical reaction conditions. The catalytic activity of the different Rh surfaces, particularly their tolerance towards poisoning by CO, was found to be strongly dependent on the density of steps and defects, as well as on the size (µm vs. nm) of the respective catalytically active surface. Graphic Abstract

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42

Keska, J. K., and R. D. Fernando. "Average Physical Parameters in an Air-Water Two-Phase Flow in a Small, Square-Sectioned Channel." Journal of Fluids Engineering 116, no. 2 (June 1, 1994): 247–54. http://dx.doi.org/10.1115/1.2910262.

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This experimental study focuses on an adiabatic two-phase air-water flow generated in a small, horizontal, 6.35 mm square channel. Pressure and temperature were near standard conditions. Experimental data and correlations available in the literature, generally, do not consider the full range of concentration, small cross-sectional areas and direct physical parameters, such as concentration (void fraction) and/or phase velocities. Based on the direct measurement of in-situ spatial concentration (in a full range of concentrations, including gas and liquid phases only), and flow-pattern determination, the experimental data from the study are compared with data from the literature and with prediction by the generally accepted Lockhart-Martinelli’s and Chen’s models. Spatial concentration measurements were made with a computer-based system developed and built by the authors. Pressure drop over a length of the channel was also measured with pressure transducers. These measurements were made for a variety of flow conditions which encompassed bubble, slug, plug, and annular flow regimes. Flow patterns were established, and both mean and fluctuating components of the concentration measurements were used to objectively identify the flow patterns. These results, together with visual enhanced observation (stroboscope) supplemented with a high-speed CCD camera recording enhanced with dye injection, were used to obtain flow-pattern maps and compared with the literature. Spatial concentration is shown to be a key physical parameter in describing the state of the mixture in two-phase flow.

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Schurek, H. J., U. Jost, H. Baumgartl, H. Bertram, and U. Heckmann. "Evidence for a preglomerular oxygen diffusion shunt in rat renal cortex." American Journal of Physiology-Renal Physiology 259, no. 6 (December 1, 1990): F910—F915. http://dx.doi.org/10.1152/ajprenal.1990.259.6.f910.

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Although blood flow to the renal cortex is high and oxygen extraction is low, the renal cortex is remarkably susceptible to hypoxia. Because erythropoietin production has been localized mainly to the renal cortex, the aim of this study was to find a common denominator for both the high susceptibility to hypoxia and oxygen sensing within the renal cortex. By direct measurement of oxygen pressure with microcoaxial needle sensors at superficial glomeruli of the in situ kidney of anesthetized Munich-Wistar-Fromter rats, we obtained mean partial pressure of O2 (PO2) values of 46 +/- 13 (SD) mmHg (n = 71). The simultaneously measured systemic PO2 in arterial blood was 90 +/- 8 mmHg (n = 54). Changing the respirator gas from air to pure oxygen enhanced systemic arterial PO2 to 593 +/- 27 mmHg, whereas PO2 at the superficial glomeruli increased only to a mean of 80 +/- 28 mmHg (n = 71). These data suggest significant preglomerular shunting of oxygen within the cortical vasculature, most likely between interlobular vessels, which are arranged in a countercurrent fashion and represent quantitatively the largest contact area between arteries and veins within the renal cortex.

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Solanki, G. K., Dipika B. Patel, Sandip Unadkat, N. N. Gosai, and Yunus Gafur Mansur. "Growth, Structural and High Pressure Study of GeS_0.25Se_0.75 and GeS_0.75Se_0.25 Single Crystals." Advanced Materials Research 665 (February 2013): 37–42. http://dx.doi.org/10.4028/www.scientific.net/amr.665.37.

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The orthorhombic semi-conducting compound GeS0.25Se0.75 and GeS0.75Se0.25 possess interesting electrical properties and can been the subject of numerous investigations. The changes in solids under high pressure can reveal several new features of interatomic forces, which are responsible for their diverse physical properties. Authors have carried out growth of GeS0.25Se0.75 and GeS0.75Se0.25 crystals by Direct Vapor Transport (DVT) technique. For compositional confirmation energy dispersive analysis of X-ray (EDAX) has been used. EDAX results show that the grown crystals are nearly stoichiometrycally perfect. The grown crystals have been characterized by X-ray diffraction technique (using Philips X Pert MPD diffractometer) for structural characterization. These crystals are crystallized in orthorhombic structure. The values of lattice parameters, unit cell volume and X-ray density are calculated and presented. It is observed from lattice parameters, unit cell volume and X-ray density, that as the content of sulfur increases the value of all the lattice parameters decreases. High pressure study is also of great importance to visualize the mechanism governing the structural changes and to reveal solid state properties associated with different structure. For the room temperature measurement of resistance as a function of pressure, up to 7 GPa, the sample was set at the centre of the talc disc on the lower anvil. The pressure was generated by a hydraulic press on the Bridgman type tungsten carbide opposed anvil apparatus with in-situ Bismuth pressure calibration. The resistance was measured in several independent runs on these crystals as a function of pressure and was found to be reproducible. The results of variation of electrical resistance do not show presence of any phase transition up to 7 GPa. We investigate in GeS0.25Se0.75 and GeS0.75Se0.25 single crystals that as sulfur content increases, resistance of this compound increases.

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Calvello, M., F. Esposito, G. Pavese, and C. Serio. "Physical and optical properties of atmospheric aerosol by in-situ and radiometric measurements." Atmospheric Chemistry and Physics Discussions 9, no. 6 (November 27, 2009): 25565–97. http://dx.doi.org/10.5194/acpd-9-25565-2009.

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Abstract. Physical and optical properties of atmospheric aerosols collected by using a high resolution (1.5 nm) spectroradiometer (spectral range 400–800 nm), a 13 stages Dekati Low Pressure Impactor (size range 30 nm–10 μm), and an AE31 Aethalometer (7 wavelenghts from 370 nm to 950 nm), have been examined in a semi-rural site in Southwest Italy (Tito Scalo, 40°35´ N, 15°41´ E, 750 m a.s.l.). In particular, daily averaged values of AOD and Ångström turbidity parameters from radiometric data together with mass-size distributions from impactor data and Black Carbon (BC) concentrations have been analyzed from May to October 2008. Furthermore, by inverting direct solar radiances, aerosol columnar number and volume size distributions have been obtained for the same period. Comparison of different observation methods, allowed to verify if, and in what conditions, changes in aerosol properties measured at ground are representative of columnar properties variations. Agreement between columnar and in-situ measurements has been obtained in case of anthropogenic aerosol loading, while in case of Saharan dust intrusions some discrepancies have been found when dust particles were located at high layers in the atmosphere (4–8 km) thus affecting columnar properties more than surface ones. For anthropogenic aerosols, a good correlation has been confirmed through the comparison of fine aerosol fraction contribution as measured by radiometer, impactor and aethalometer, suggesting that in this case particles are more homogeneously distributed over the lower layers of atmosphere and columnar aerosol optical properties are dominated by surface measured component.

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Calvello, M., F. Esposito, G. Pavese, and C. Serio. "Physical and optical properties of atmospheric aerosols by in-situ and radiometric measurements." Atmospheric Chemistry and Physics 10, no. 5 (March 2, 2010): 2195–208. http://dx.doi.org/10.5194/acp-10-2195-2010.

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Abstract. Physical and optical properties of atmospheric aerosols collected by using a high resolution (1.5 nm) spectroradiometer (spectral range 400–800 nm), a 13-stage Dekati Low Pressure Impactor (size range 30 nm–10 μm), and an AE31 Aethalometer (7 wavelenghts from 370 nm to 950 nm), have been examined in a semi-rural site in Southwest Italy (Tito Scalo, 40°35' N, 15°41' E, 750 m a.s.l.). In particular, daily averaged values of AOD and Ångström turbidity parameters from radiometric data together with mass-size distributions from impactor data and Black Carbon (BC) concentrations have been analyzed from May to October 2008. Furthermore, by inverting direct solar radiances, aerosol columnar number and volume size distributions have been obtained for the same period. The comparison of different observation methods, allowed to verify if, and in what conditions, changes in aerosol properties measured at ground are representative of columnar properties variations. Agreement between columnar and in-situ measurements has been obtained in case of anthropogenic aerosol loading, while in case of Saharan dust intrusions some discrepancies have been found when dust particles were located at high layers in the atmosphere (4–8 km) thus affecting columnar properties more than surface ones. For anthropogenic aerosols, a good correlation has been confirmed through the comparison of fine aerosol fraction contribution as measured by radiometer, impactor and aethalometer, suggesting that, in this case, the particles are more homogeneously distributed over the lower layers of atmosphere and columnar aerosol optical properties are dominated by surface measured component.

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Zhang, Gengxin, Hailiang Dong, Zhiqin Xu, Donggao Zhao, and Chuanlun Zhang. "Microbial Diversity in Ultra-High-Pressure Rocks and Fluids from the Chinese Continental Scientific Drilling Project in China." Applied and Environmental Microbiology 71, no. 6 (June 2005): 3213–27. http://dx.doi.org/10.1128/aem.71.6.3213-3227.2005.

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ABSTRACT Microbial communities in ultra-high-pressure (UHP) rocks and drilling fluids from the Chinese Continental Scientific Drilling Project were characterized. The rocks had a porosity of 1 to 3.5% and a permeability of ∼0.5 mDarcy. Abundant fluid and gas inclusions were present in the minerals. The rocks contained significant amounts of Fe2O3, FeO, P2O5, and nitrate (3 to 16 ppm). Acridine orange direct counting and phospholipid fatty acid analysis indicated that the total counts in the rocks and the fluids were 5.2 × 103 to 2.4 × 104 cells/g and 3.5 × 108 to 4.2 × 109 cells/g, respectively. Enrichment assays resulted in successful growth of thermophilic and alkaliphilic bacteria from the fluids, and some of these bacteria reduced Fe(III) to magnetite. 16S rRNA gene analyses indicated that the rocks were dominated by sequences similar to sequences of Proteobacteria and that most organisms were related to nitrate reducers from a saline, alkaline, cold habitat; however, some phylotypes were either members of a novel lineage or closely related to uncultured clones. The bacterial communities in the fluids were more diverse and included Proteobacteria, Bacteroidetes, gram-positive bacteria, Planctomycetes, and Candidatus taxa. The archaeal diversity was lower, and most sequences were not related to any known cultivated species. Some archaeal sequences were 90 to 95% similar to sequences recovered from ocean sediments or other subsurface environments. Some archaeal sequences from the drilling fluids were >93% similar to sequences of Sulfolobus solfataricus, and the thermophilic nature was consistent with the in situ temperature. We inferred that the microbes in the UHP rocks reside in fluid and gas inclusions, whereas those in the drilling fluids may be derived from subsurface fluids.

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48

Legge, NJ, and DJ Connor. "Hydraulic Characteristics of Mountain Ash (Eucalyptus regnans F. Muell.) Derived From in situ Measurements of Stem Water Potential." Functional Plant Biology 12, no. 1 (1985): 77. http://dx.doi.org/10.1071/pp9850077.

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An osmotic tensiometer has been successfully used for in situ measurements of stem water potential, Ψst, in mountain ash. During spring and early summer when soils were saturated, fluctuations in Ψst, at a given height in different trees were very similar. When Ψst, values were measured at different positions around the circumference of individual trees during late summer, considerable variation between the different positions was recorded. The data at this time also suggest that night temperatures above 17°C can lead to stomatal opening, but this was not confirmed by direct measurement. Possible reasons for apparent discrepancies between leaf and stem water potential measurements are discussed. The time lag between vapour pressure deficit and Ψst was around 2 h whenΨst values were high, but fell to 10 min or less for Ψst values below about - 1.2 MPa. Analysing this time lag in terms of a resistance-capacitance model of water flow made it possible to estimate the storage-to-vessel transfer resistance as 1.7 × 107 Pa s m3 kg-1.

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49

Wen, Caihong, Yan Xue, and Arun Kumar. "Ocean–Atmosphere Characteristics of Tropical Instability Waves Simulated in the NCEP Climate Forecast System Reanalysis." Journal of Climate 25, no. 18 (April 28, 2012): 6409–25. http://dx.doi.org/10.1175/jcli-d-11-00477.1.

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Abstract The NCEP Climate Forecast System Reanalysis (CFSR) represents a new effort with the first guess from a high-resolution coupled system and offers prospects for improved simulation of mesoscale air–sea coupled variability. This study aims to describe the characteristics of ocean–atmosphere covariability associated with tropical instability waves (TIWs) in the Pacific for the CFSR, and to assess how well they agree with in situ and satellite observations. Multiyear daily high-resolution CFSR data are used to describe variability associated with TIWs. Results show that TIW-induced SST variations exhibit pronounced seasonal and interannual variability that are tightly connected with cold tongue variations. The analysis illustrates coherent patterns associated with TIWs, both in the ocean and the atmosphere. Moisture and air temperature maximums are located west of SST maximums, leading to downstream displacement of surface pressure minimums relative to SST maximums. Surface winds accelerate (decelerate) over warm (cold) water, and a thermally direct circulation is created. Significant signals are observed in low-level cloud cover, which are closely in phase with surface wind convergences. The magnitudes of TIW-induced surface wind, surface pressure, and cloud cover perturbations agree well with in situ and satellite observations. Further analysis shows that surface net heat flux perturbations are dominated by latent heat fluxes and have a large negative feedback on TIW SST variability (~40 W m−2 °C−1). Water vapor perturbation is the primary factor contributing to changes in latent heat fluxes, while SST-induced wind perturbation plays a secondary role. The analysis presented here highlights that the CFSR provides an unprecedented opportunity to study the physical mechanisms for the TIWs, as well as their influences on climate variability.

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50

Bertram, T. H., J. R. Kimmel, T. A. Crisp, O. S. Ryder, R. L. N. Yatavelli, J. A. Thornton, M. J. Cubison, M. Gonin, and D. R. Worsnop. "A field-deployable, chemical ionization time-of-flight mass spectrometer: application to the measurement of gas-phase organic and inorganic acids." Atmospheric Measurement Techniques Discussions 4, no. 2 (March 22, 2011): 1963–87. http://dx.doi.org/10.5194/amtd-4-1963-2011.

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Abstract. We report a new field-deployable chemical ionization time-of-flight mass spectrometer (CI-TOFMS) for the direct measurement of trace gases in the atmosphere. We apply the technique to the measurement of gas-phase inorganic and organic acids via negative-ion proton transfer, using acetate as the reagent ion. A novel high pressure interface, incorporating two RF-only quadrupoles is used to efficiently focus ions through four stages of differential pumping before analysis with a compact TOFMS. The high ion-duty cycle (>20%) of the TOFMS, coupled to efficient production and transmission of ions in the high pressure interface results in a highly sensitive (>300 ions s−1 pptv−1) instrument capable of the fast measurement of atmospheric gases at trace levels. We demonstrate the efficient transfer and detection of both bare ions and ion-molecule clusters, and characterize the instrument during field measurements aboard the R/V Atlantis as part of the CalNex campaign during the spring of 2010. The in-field short-term precision is better than 5% at 1 pptv (pL/L), for 1-second averages. The detection limit (3σ, 1-second averages) of the current version of the CI-TOFMS, as applied to the in situ detection of gas-phase acids, is limited by the magnitude and variability in the background determination and was determined to be 4 pptv.

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Journal articles on the topic 'Direct in situ high-pressure preconcentration'

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