Screening of Surfactants for Flooding at High-Mineralization Conditions: Two Production Zones of Carbonate Reservoir

The selection of effective surfactants potentially can mobilize oil up to 50% of residuals in mature carbonate oilfields. Surfactants’ screening for such oilfields usually is complicated by the high salinity of water, high lipophilicity of the rock surface, and the heterogeneous structure. A consideration of features of the oilfield properties, as well as separate production zones, can increase the deep insight of surfactants’ influence and increase the effectiveness of surfactant flooding. This article is devoted to the screening of surfactants for two production zones (Bashkirian and Vereian) of the Ivinskoe carbonate oilfield with high water salinity and heterogeneity. The standard core study of both production zones revealed no significant differences in permeability and porosity. On the other hand, an X-ray study of core samples showed differences in their structure and the presence of microporosity in the Bashkirian stage. The effectiveness of four different types of surfactants and surfactant blends were evaluated for both production zones by two different oil displacement mechanisms: spontaneous imbibition and filtration experiments. Results showed the higher effect of surfactants on wettability alteration and imbibition mechanisms for the Bashkirian cores with microporosity and a higher oil displacement factor in the flooding experiments for the Vereian homogeneous cores with lower oil viscosity.

Numerical Investigation of Heat Transfer Characteristics of scCO2 Flowing in a Vertically-Upward Tube with High Mass Flux

In this work, the heat transfer characteristics of supercritical pressure CO2 in vertical heating tube with 10 mm inner diameter under high mass flux were investigated by using an SST k-ω turbulent model. The influences of inlet temperature, heat flux, mass flux, buoyancy and flow acceleration on the heat transfer of supercritical pressure CO2 were discussed. Our results show that the buoyancy and flow acceleration effect based on single phase fluid assumption fail to explain the current simulation results. Here, supercritical pseudo-boiling theory is introduced to deal with heat transfer of scCO2. ScCO2 is treated to have a heterogeneous structure consisting of vapor-like fluid and liquid-like fluid. A physical model of scCO2 heat transfer in vertical heating tube was established containing a gas-like layer near the wall and a liquid-like fluid layer. Detailed distribution of thermophysical properties and turbulence in radial direction show that scCO2 heat transfer is greatly affected by the thickness of gas-like film, thermal properties of gas-like film and turbulent kinetic energy in the near-wall region. Buoyancy parameters Bu < 10-5, Bu* < 5.6 × 10−7 and flow acceleration parameter Kv < 3 × 10−6 in this paper, which indicate that buoyancy effect and flow acceleration effect has no influence on heat transfer of scCO2 under high mass fluxes. This work successfully explains the heat transfer mechanism of supercritical fluid under high mass flux.

Evaluating critiques of evidence of historically heterogeneous structure and mixed-severity fires across dry-forest landscapes of the western USA

The structure and role of fire in historical dry forests, ponderosa pine (Pinus ponderosa) and dry mixed-conifer forests, of the western USA, have been debated for 25 years, leaving two theories. The first, that these forests were relatively uniform, low in tree density and dominated by low- to moderate-severity fires was recently reviewed, including a critique of opposing evidence. The second, that these forests historically had heterogeneous structure and a mixture of fire severities, has had several published reviews. Here, as authors in part of the second theory, we critically examined evidence in the first theory’s new review, which presented 37 critiques of the second theory. We examined evidence for and against each critique, including evidence presented or omitted. We found that a large body of published evidence against the first theory and supporting the second theory, presented in 10 published rebuttals and 25 other published papers, by us and other scientists, was omitted and not reviewed. We reviewed omitted evidence here. Omitted evidence was extensive, and included direct observations by early scientists, maps in early forest atlases, early newspaper accounts and photographs, early aerial photographs, seven paleo-charcoal reconstructions, ≥18 tree-ring reconstructions, eight land-survey reconstructions, and an analysis of forest-inventory age data. This large body of omitted published research provides compelling evidence supporting the second theory, that historical dry forests were heterogeneous in structure and had a mixture of fire severities, including high-severity fire. The first theory is rejected by this large body of omitted evidence.

Central Pontine Myelinolysis in a Child: Clinical Case

Background. Central pontine myelinolysis (CPM) is limited symmetric non-inflammatory demyelination in the middle part of pontine. This disease is based on electrolyte balance disorders. Although CPM was firstly described in adults, but it can also occur in children. Every new case of CPM in children has undeniable interest and high scientific and practical significance due to its low incidence. Clinical case description. The child, 7 years old, had acute development, lethargy, multiple vomiting, subfebrile fever, pains in epigastric region. It has happened after drinking an unknown herb growing in the yard and previously covered with the insecticide "Akarin", according to the mother. The child was hospitalized in the pediatric department at the place of residence. The patient developed strabismus, swallowing disorder, and muscle weakness on infusion therapy. Biochemical blood test has shown hypokalemia and hyponatremia. Head MRI has shown symmetrical focal lesion of heterogeneous structure in pontine. Conclusion. Distinctive feature of this case is the development of CPM in a child on the ongoing therapy of hypokalemia and hyponatremia. The timely provision of qualified medical care has favoured the child's recovery.

Enhanced Transdermal Delivery of Pranoprofen Using a Thermo-Reversible Hydrogel Loaded with Lipid Nanocarriers for the Treatment of Local Inflammation

A biocompatible topical thermo-reversible hydrogel containing Pranoprofen (PF)-loaded nanostructured lipid carriers (NLCs) was studied as an innovative strategy for the topical treatment of skin inflammatory diseases. The PF-NLCs-F127 hydrogel was characterized physiochemically and short-time stability tests were carried out over 60 days. In vitro release and ex vivo human skin permeation studies were carried out in Franz diffusion cells. In addition, a cytotoxicity assay was studied using the HaCat cell line and in vivo tolerance study was performed in humans by evaluating the biomechanical properties. The anti-inflammatory effect of the PF-NLCs-F127 was evaluated in adult male Sprague Daw-ley® rats using a model of inflammation induced by the topical application of xylol for 1 h. The developed PF-NLCs-F127 exhibited a heterogeneous structure with spherical PF-NLCs in the hydrogel. Furthermore, a thermo-reversible behaviour was determined with a gelling temperature of 32.5 °C, being close to human cutaneous temperature and thus favouring the retention of PF. Furthermore, in the ex vivo study, the amount of PF retained and detected in human skin was high and no systemic effects were observed. The hydrogel was found to be non-cytotoxic, showing cell viability of around 95%. The PF-NLCs-F127 is shown to be well tolerated and no signs of irritancy or alterations of the skin’s biophysical properties were detected. The topical application of PF-NLCs-F127 hydrogel was shown to be efficient in an inflammatory animal model, preventing the loss of stratum corneum and reducing the presence of leukocyte infiltration. The results from this study confirm that the developed hydrogel is a suitable drug delivery carrier for the transdermal delivery of PF, improving its dermal retention, opening the possibility of using it as a promising candidate and safer alternative to topical treatment for local skin inflammation and indicating that it could be useful in the clinical environment.

Wave theory of the laminated plates with approximate consideration of the transverse shear

Composite materials are widely used in the production of aircraft for various purposes. Having several unique properties, composites, due to their heterogeneous structure, are poorly resistant to shock loads. Impulse action spreads inside the material in the form of stress waves, which are reflected on internal inhomogeneities, can overlap, and create very significant bursts of stress. This often leads to the well-known types of failure – spalling and delamination. Practice shows that these fractures occur almost immediately after the loading impulse. To verify the spalling strength, it is necessary to consider the initial unsteady phase of the response to the external impulse. There are sufficiently reliable theories to verify this strength; usually, they do not take transverse shear into account, otherwise the solution becomes unnecessarily cumbersome and poorly observable. Nevertheless, attempts are often made to refine the calculations by approximate consideration of transverse shear. This article presents the wave theory of laminated plates with approximate consideration of transverse shear. The possibility of specifying the calculation of impulse-loaded plates is considered. The inconsistency of the resulting model is proved.

The Comparison of the Results of Ultrasound, CT and MRI in the Diagnosis of Angiomyolipoma Kidneys, Including Complicated by Development of the Syndrome Wunderlich

Purpose: Analysis the effectiveness of various methods of radiation studies for the detection of renal angiomyolipomas (RAMLs), including the diagnosis of Wunderlich syndrome. Material and methods: The analysis of the results of a comprehensive radiation study of the kidneys of 115 patients who were diagnosed with focal formation in primary renal ultrasound was carried out. Further, of those 115 people, 47 patients underwent MRI of the kidneys, 60 patients – CT and 8 patients complex MRI+CT, including contrast-enhanced vasculature. Results and discussion: Angiomyolipoma was detected by ultrasound in 38 (33.0 %) of 115 patients, and according to MRI and CT in total in 27 (23.5 %) patients. Coincidence of ultrasound findings and MRI and CT results was in 18 patients. Consequently, the sensitivity of ultrasound in the diagnosis of RAML was compared with MRI – 45 %; when compared with CT – 42.8 %, and specificity – 55 % and 57.1 %, respectively. Reliable signs of RAML in ultrasound were hyperechogenic homogeneous structure, clear smooth contours of the formation. The rounded form of education is statistically unreliable. Statistically significant characteristics of RAML in magnetic resonance imaging are heterogeneous structure, heterogeneous hyperintense MR-signal on T1 and heterogeneously hypointensity on T2-weighted images, always uniformly hypo-Fs for T1 / T2 Fs, with hypo clear boundary between education and renal parenchyma on T1 in the opp phase. Reliable signs of RAML with CT are non-uniform structure of education, with non-uniform x-ray density. Conclusion: Ultrasound diagnosis is necessary for screening kidney disease, while CT and MRI have greater sensitivity and specificity to determine the nature of focal formation. With the development of Wunderlich’s syndrome, a complex of radiological methods, including ultrasound, MRI and CT, allows to diagnose the cause of hemorrhage, as well as to obtain complete diagnostic information necessary for the surgeon to plan treatment.