Understanding organic matter properties in terms of maturity and production potential are crucial for the initial assessment of unconventional plays. This is important since the amount of hydrocarbon ...that can be generated is a function of organic matter type and content in the formation and its thermal maturity. The complexity of shale plays in terms of constituent components has demonstrated that new analytical methods should be acquired to better understand hydrocarbon generation processes. In this study, a few samples from the upper and lower members of the Bakken Formation in the USA were selected from different depths and maturity levels. The samples were analyzed by a high frequency (22 MHz) nuclear magnetic resonance (NMR relaxometry) equipment, followed by Rock-Eval pyrolysis (using the Basic/Bulk-Rock method for all samples and a multi-heating rate method, MHR, for the two least mature samples) and bitumen reflectance evaluations. Results showed NMR can detect different hydrogen populations within the samples and distinguish among phases, such as solid organic matter, hydrocarbons (mobile oil), and water by T1-T2 mapping. We were also able to relate different identified areas on NMR T1-T2 maps to geochemical parameters of the organic matter obtained from Rock-Eval pyrolysis (such as S1, S2, and HI) and with thermal maturity (vitrinite reflectance-equivalent).
•Modified pyrolysis methods are needed to determine Oil-In-Place in liquids-rich rocks.•NMR T1-T2 relaxometry and Multi Heating pyrolysis were used to study HC producibility.•HF-NMR at 22 °C ...underestimates the amount of OIP for certain types of organic-rich LRU.•Any chemically ‘extractable’ hydrocarbons are not necessarily ‘producible’
The geochemical and petrophysical complexity of source-rock reservoirs in liquids-rich unconventional (LRU) plays necessitates the implementation of a more expansive analytical protocol for initial play assessment. In this study, original samples from selected source-rock reservoirs in the USA and the UK were analyzed by 22 MHz nuclear magnetic resonance (HF-NMR) T1-T2 mapping, followed by hydrous pyrolysis, and a modified Rock-Eval pyrolysis method (multi-heating step method-MHS). The above methods were complemented by organic petrography under reflected white and UV light excitation of the original and pyrolyzed samples. The analytical protocol presented attempts to better qualify and quantify different petroleum fractions (mobile, heavy hydrocarbons, viscous, solid bitumen), thus provide valuable and refined information about producibility of target intervals during appraisal. Results show how the hydrocarbon fractions interpreted from peak locations and intensities on NMR T1-T2 maps are in good agreement with those from MHS pyrolysis in terms of hydrocarbon mobility/producibility. Results from HP (Hydrous Pyrolysis) experiments show that an exception to this general agreement between NMR and MHS estimates occurs for the Kimmeridge Blackstone Clay samples, where MHS shows an increase of >90% in producible hydrocarbon yields vs. minimal to no presence of mobile hydrocarbons in NMR T1-T2 maps. This study clarifies the role of pore structure and networks in these discrepancies of producible oil estimates when comparing programmed pyrolysis to NMR-based techniques. This novel, multi-step and multidisciplinary approach provides a more advanced screening protocol for identifying zones of higher oil-in-place (OIP) and predicting fluid mobility prior to drilling or completions.
Multimodality imaging based on complementary detection principles has broad clinical applications and promises to improve the accuracy of medical diagnosis. This means that a tracer particle ...advantageously incorporates multiple functionalities into a single delivery vehicle. In the present work, we explore a unique combination of MRI and photoacoustic tomography (PAT) to detect picomolar concentrations of nanoparticles. The nanoconstruct consists of ferromagnetic (Co) particles coated with gold (Au) for biocompatibility and a unique shape that enables optical absorption over a broad range of frequencies. The end result is a dual-modality probe useful for the detection of trace amounts of nanoparticles in biological tissues, in which MRI provides volume detection, whereas PAT performs edge detection.
Implementation of a low-field time-domain nuclear magnetic resonance (NMR) scanner as a diagnostic tool in the production of new polymer components is described in the context of qualification of a ...new QA/QC device. A study to determine the optimal experimental parameters was performed and a robotic autosampler was built to enable scanning of multiple pads. Relationships between
T
2 values and physical properties of DC745 slabs were investigated, and the appropriate sampling parameters for the production setting were determined. Two versions of a robotic autosampler were built and, for the component described here, a fourth radial axis was required in addition to traditional
X,
Y, and
Z movement to eliminate the large variability in
T
2 due to inconsistent sample coverage caused by the complex rib geometry of the component. Data show that with appropriate choice of experimental conditions of the NMR detector and the detection geometry of the robotic autosampler, sufficient resolution of variations in cross-link density on the millimeter scale could be determined. All data to date demonstrate that low-field NMR devices are a feasible tool for use in production settings for non-destructive quality control of polymer components.
One of the much debated mysteries in 1H NMR relaxation measurements of bitumen and heavy crude oils is the departure from expected theoretical trends at high viscosities, where traditional theories ...of 1H–1H dipole–dipole interactions predict an increase in T 1 with increasing viscosity. However, previous experiments on bitumen and heavy crude oils clearly show that T 1LM (i.e., log-mean of the T 1 distribution) becomes independent of viscosity at high viscosities; in other words, T 1LM versus viscosity approaches a plateau. We report 1H NMR data at ambient conditions on a set of pure polymers and polymer–heptane mixes spanning a wide range of viscosities (η = 0.39 cP ↔ 334 000 cP) and NMR frequencies (ω0/2π = f 0 = 2.3 MHz ↔ 400 MHz) and find that at high viscosities (i.e., in the slow-motion regime) T 1LM plateaus to a value T 1LM> ∝ ω0 independent of viscosity, similar to bitumen. More specifically, on a frequency-normalized scale, we find that T 1LM> × 2.3/f 0 ≃ 3 ms (i.e., normalized relative to 2.3 MHz), in good agreement with bitumen and previously reported polymers. Our findings suggest that in the high-viscosity limit T 1LM> and T 2LM> for polymers, bitumen, and heavy crude oils can be explained by 1H–1H dipole–dipole interactions without the need to invoke surface paramagnetism. In light of this, we propose a new relaxation model to account for the viscosity and frequency dependences of T 1LM and T 2LM, solely based on 1H–1H dipole–dipole interactions. We also determine the surface relaxation components T 1S and T 2S of heptane in the polymer–heptane mixes, where the polymer acts as the “surface” for heptane. We report ratios up to T 1S/T 2S ≃ 4 and dispersion T 1S(ω0) for heptane in the mix, similar to previously reported data for hydrocarbons confined in organic matter such as bitumen and kerogen. These findings imply that 1H–1H dipole–dipole interactions enhanced by nanopore confinement dominate T 1S and T 2S relaxation in saturated organic-rich shales.
Apoptosis. Molecules and mechanisms Konopleva, M; Zhao, S; Xie, Z ...
Advances in experimental medicine and biology,
1999, Letnik:
457
Journal Article
Recenzirano
This review of the molecules and pathways involved in programmed cell death (apoptosis) discriminates triggers of apoptosis (e.g. chemotherapy, radiation, Fas ligation), modulators of apoptosis (e.g. ...Bcl-2 family members, Bcl-2 interacting proteins, Apafs, IAPs, and Fas/FasL modulators including FLICE and FLIPs), effectors (caspases 1-13) and cleavage substrates (e.g. PARP). Special consideration is given to the structure-function relationship of Bcl-2 family members and to their post-transcriptional modification. Brief references are made to the role of apoptotic pathway in leukemias and lymphomas and to strategies of modulating apoptotic pathways.
We observed that curry leaf (Murraya koenigii) extract possesses the property to decrease blood cholesterol and blood glucose levels in diabetic ob/ob mice. Mice received daily intraperitoneal ...injections of 80 mg/kg curry leaf extract for 10 consecutive days. The extract significantly decreased blood cholesterol level from 277.6 +/- 16.6 mg/d (day 0) to 182.0 +/- 15.3 mg/d (day 10, p < 0.01 compared with the change in vehicle group). The extract also significantly decreased blood glucose level from 387.0 +/- 15.6 mg/dl (day 0) to 214.0 +/- 26.6 mg/dl (day 10, p < 0.01). In addition, body weight was reduced after extract treatment. Our data suggest that curry leaf may be proved to be of clinical importance in improving the management of high cholesterol level and type 2 diabetes.
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