OILWELL COMPLETION FLUID SOLIDS INTERACTION WITH AN UNCONSOLIDATED OIL RESERVOIR

This work addresses the problem of modelling, detection and evaluation of the mechanical interaction between oilwell completion fluid particles and granular reservoir rocks. These interactions contribute to a reservoir productivity reduction known as the “permeability damage” phenomenon.

Fundamental concepts of cake filtration and filter medium filtration were used to formulate mathematical models of particles capturing: gradual pore blocking, screening, and straining. The models provide theoretical bases for simple diagnostic plots in which the linearity of a plot becomes an indication of a prevailing mechanism of particles' capture.

Laboratory tests were run by pumping a completion fluid through synthetic simulated cores of unconsolidated sandstone gas reservoir samples from the Adriatic Sea. By using diagnostic plots and grade passing efficiency curves, the effects of total solids concentration particle size on the type and efficiency of the capture mechanism were investigated.

The study revealed the existence of three mechanisms of particle capture and the applicability of diagnostic plots for their detection. The onset of the straining mechanisms was attributed mainly to the total solids concentration while the duration of the gradual pore blockage phase was correlated with both particle size and concentration.     

Dielectrc Polarization of Animal Lung at Radio Frequencies

Dielectric properties of the inflated and deflated fceline lung in vivo were investigated at frequencies from 10 kHz to 100 MHz. A computer-controlled network analyzer and a multiring capacitive sensor were employed. It was found that in the frequency range investigated, both the dielectric constant and the conductivity of the deflated lung were higher than those of the inflated one. The analysis of the experimental data was performed using two approaches: the loss-tangent method and the curve-fitting computer program called STEPIT. It was found that in the middle band of frequencies for both inflated and deflated states of the lung, the dielectric response mainly reflects the membrane polarization of the capillary erythrocytes with possible contributions of other components, e.g., the pulmonary microphages. The dielectric relaxation time for the capillary erythrocytes in the lung is similar to that for the packed cells, which is much longer than for the erythrocytes at physiological concentrations. The dielectric parameters at low frequencies obtained using the STEPIT program differ significantly between the inflated and deflated lung. The observed dielectric data reflect at least two overlapping dispersions: of lung capillary erythrocytes and of cellular structures forming the alveoli.     

Multiple Antenna Enhancements for a High Rate CDMA Packet Data System

A High Data Rate (HDR) system has been proposed for providing downlink wireless packet service by using a channel-aware scheduling algorithm to transmit to users in a time-division multiplexed manner. In this paper, we propose using multiple antennas at the transmitter and/or at the receiver to improve performance of an HDR system. We consider the design tradeoffs between scheduling and multi-antenna transmission/detection strategies and investigate the average Shannon capacity throughput as a function of the number of antennas assuming ideal channel estimates and rate feedback. The highest capacities are achieved using multiple antennas at both the transmitter and receiver. For such systems, the best performance is achieved using a multi-input multi-output capacity-achieving transmission scheme such as BLAST (Bell Labs Layered Space-Time) in which the transmitted signal is coded in space and time, and the receive antennas are used to resolve the spatial interference. In the second part of the paper, we discuss practical transmitter and receiver architectures using BLAST for approaching the theoretical gains promised by the capacity analysis. Because the terminal receivers will be portable devices with limited computational and battery power, we perform a computational complexity analysis of the receiver and make high-level assessments on its feasibility. We conclude that the overall computational requirements are within the reach of current hardware technology.     

Quantitative effects of acquisition duration and temporal resolution on the measurement accuracy of prostate dynamic contrast-enhanced MRI data: a phantom study

Objectives

The aim of this study was to investigate the effect of the temporal resolution (T _res) and acquisition duration (AD) on the measurement accuracy of contrast concentration–time curves (CTCs), and derived phenomenological and pharmacokinetic parameter values, in a dynamic contrast-enhanced MRI experiment using a novel phantom test device.

Materials and methods

‘Ground truth’ CTCs were established using a highly precise optical imaging system. These precisely known CTCs were produced in an anthropomorphic environment, which mimicked the male pelvic region, and presented to the MRI scanner for measurement. The T _res was varied in the range [2–24.4 s] and the AD in the range [30–600 s], and the effects on the measurement accuracy were quantified.

Results

For wash-in parameter measurements, large underestimation errors (up to 40%) were found using T _res values ≥16.3 s; however, the measured wash-out rate did not vary greatly across all T _res values tested. Errors in derived K ^trans and v _e values were below 14 and 12% for acquisitions with {T _res ≤ 8.1 s, AD ≥ 360 s} and {T _res ≤ 16.3 s, AD ≥ 360 s}, respectively, but increased dramatically outside these ranges.

Conclusions

Errors in measured wash-in, wash-out, K ^trans, and v _e parameters were minimised using T _res ≤ 8.1 s and AD ≥ 360 s, with large errors recorded outside of this range.

     

Effect of green manure and supplemental fertility amendments on selected soil quality parameters in an organic potato rotation in Eastern Canada

The effects of green manure, crop sequence and off-farm composts on selected soil quality parameters were assessed in a three-year organic potato (Solanum tuberosum L.) rotation in Eastern Canada. Three crop sequences varying in preceding green manure [red clover (RCl) + RCl, and beans/buckwheat or carrots + oats/peas/vetch mixture (OPV)] as main plots and four fertility treatments applied in the potato phase only [control; inorganic fertilizer; municipal solid waste compost (MSW); composted paper mill biosolid (PMB)] as subplots were compared. In 2008 and 2010, changes in selected soil quality parameters (0–15 cm) were assessed prior to planting of potatoes and at potato tuber initiation stage. Potentially mineralizable nitrogen (N) and the acid phosphatase enzyme activity average values across years were greater following RCl (1.51 abs and 622 kg ha^?1) compared with OPV (1.32 abs and 414 kg ha^?1) at potato planting. Soil NO₃–N average value was greater following RCl compared with OPV (63 vs. 52 kg ha^?1) at tuber initiation. For the other measured parameters, OPV and RCl were similar. The soil organic carbon (C) and particulate organic matter-C were greater under PMB and MSW (31.1 and 7.57 kg ha^?1) compared with fertilizer treatment (27.9 and 6.05 kg ha^?1). The microbial biomass C and microbial biomass quotient were greater under MSW (216 kg ha^?1 and 0.73 %) than PMB and fertilizer (147 kg ha^?1 and 0.50 %) across crop rotations. Annual legume green manures and off-farm composts can be used to satisfy potato N requirement and maintains soil quality in organic potato rotations.     

Cellular Internalisation of an Inositol Phosphate Visualised by Using Fluorescent InsP5

When applied extracellularly, myo‐inositol hexakisphosphate (InsP₆) and myo‐inositol pentakisphosphate (InsP₅) can inhibit the growth and proliferation of tumour cells. There is debate about whether these effects result from interactions of InsP₆ and InsP₅ with intracellular or extracellular targets. We synthesised FAM‐InsP₅, a fluorescent conjugate of InsP₅ that allows direct visualisation of its interaction with cells. FAM‐InsP₅ was internalised by H1229 tumour cells, a finding that supports earlier reports that externally applied inositol phosphates can—perhaps surprisingly—enter into cells. Close examination of the process of FAM‐InsP₅ uptake suggests a mechanism of non‐receptor‐mediated endocytosis, which is blocked at 4 °C and probably involves interaction of the ligand with the glycocalyx. However, our results are difficult to reconcile with antiproliferative mechanisms that require direct interactions of externally applied InsP₅ or InsP₆ with cytosolic proteins, because internalised FAM‐InsP₅ appears in lysosomes and apparently does not enter the cytoplasm. Studies using FAM‐InsP₅ are less difficult and time‐consuming than experiments using InsP₅ or InsP₆, a factor that allowed us to analyse cellular uptake across a range of human cell types, identifying strong cell‐specific differences.     

Small‐Molecule Proteomimetic Inhibitors of the HIF‐1α–p300 Protein–Protein Interaction

The therapeutically relevant hypoxia inducible factor HIF‐1α–p300 protein–protein interaction can be orthosterically inhibited with α‐helix mimetics based on an oligoamide scaffold that recapitulates essential features of the C‐terminal helix of the HIF‐1α C‐TAD (C‐terminal transactivation domain). Preliminary SAR studies demonstrated the important role of side‐chain size and hydrophobicity/hydrophilicity in determining potency. These small molecules represent the first biophysically characterised HIF‐1α–p300 PPI inhibitors and the first examples of small‐molecule aromatic oligoamide helix mimetics to be shown to have a selective binding profile. Although the compounds were less potent than HIF‐1α, the result is still remarkable in that the mimetic reproduces only three residues from the 42‐residue HIF‐1α C‐TAD from which it is derived.