The effect of CO2-philic thickeners on gravity drainage mechanism in gas invaded zone

The rate of mass transfer between the fractures and matrix in gas invaded zone can significantly influence on the oil recovery during the forced gravity drainage process. However, in this study, a new approach was suggested to improve the gravity drainage process in gas invaded zone. Poly(fluoroacrylate) (PFA), as a CO2-philic thickener, was injected into the gas invaded zone to illustrate the impact of interfacial mechanisms such as gas diffusion coefficient and interfacial tension (IFT) on oil recovery. Also, the cloud point pressures were measured to ensure that the PFA did not come out of the solution due to a phase change during IFT, gas diffusion coefficient, and gravity drainage experiments. Results showed that the CO2-PFA thickener (20000 ppm) could decrease the IFT from 56 to 24 dyne/cm compared to the pure CO2 scenario, improving the gravity drainage mechanism in the gas invaded zone. In addition, the CO2 diffusion coefficients were increased approximately more than two times during CO2-PFA injection in comparison with pure CO2 injection in both porous media and bulk oil phase scenarios at reservoir conditions. Also, an incremental oil recovery of 16 percent was achieved during PFA/CO2 compared to pure CO2 injection in the gas invaded zone. Therefore, gas gravity drainage is the most important mechanism once gas thickener or CO2 enters the fractures in the gas invaded zone

Cytokine gene expression in newly diagnosed multiple sclerosis patients

Multiple Sclerosis (MS) is characterized by multiple areas of inflammation, demyelination and neurodegeneration. Infiltrating Th1 CD4+ T cells secrete proinflammatory cytokines. They stimulate the release of some cytokines, expression of adhesion molecules and these cytokines may cause damage to the myelin sheath and axons. In this study, we analyzed plasma levels and gene expressions of five important cytokines in the new diagnosed MS Patients by ELISA and Real time PCR. PCR amplifications were performed to determine the IL-17, IL-23, IL-10, IL-27 and TGF-β mRNA expression levels using the SYBR Green PCR Kit. Our results showed significant decrease in IL-10, IL-27 and TGF-β but there was no significant difference in the IL-17 and IL-23 between patients and healthy controls. Altogether, our results indicated that dysregulation of cytokines, mainly increased expression of pro-inflammatory cytokines and decreased expression of inhibitory cytokines occurred in MS patients. This study may shed light to the probable role of these cytokines in neurodegeneration mechanism and current or future use of cytokines in managing and treatment of multiple sclerosis

The Effect of Gates-Glidden Drills on the Quality of Root Canal Treatment by Pre-Clinical Dental Students

AIM: This study was conducted to investigate the effect of applying Gates-Glidden (GG) drill by pre-clinical dental students on root canal treatment quality. METHOD: A total of 56 first molars consisting of 168 canals were selected in this study. For this purpose, 56 students who had been formerly trained by two methods of root canal preparation were randomly divided into two groups (n = 28). Group 1: the step-down method by GG and Group 2: step-back technique without GG. The prepared teeth were filled with gutta-percha/ZOE sealer using lateral condensation. Periapical radiographs were taken before and the following treatment to survey occurrence of preparation errors and CBCT images to determine residual dentine at furcation region. RESULTS: The findings showed that among 10 error types in specimens prepared by students, the occurrence of underfilling, overfilling, inappropriate, ledge formation, and single cone was more common without GG. There were no significant differences in residual dentine amount at furcation region between preparation with and without using GG (P > 0.05). CONCLUSION: Using GG for root canal preparation by dental students resulted in low errors and not an increased dentine removal risk

Preparation of Biodegradable Low Density Polyethylene by Starch -Urea Composition for Agricultural Applications

ABSTRACT:It has been proven that polyolefins specially low density polyethylene (LDPE), are resistant against degradation and microorganism attacks; Thus, one of the most important properties of industrial plastics, is their environmental biodegradability. Since plastics are being widely used in agriculture, horticulture and packaging, meeting this requirement becomes increasingly dificult (specially in IRAN as one of the biggest manufacturers of polyethylene materials).So, attention is focussed on production of biodegradable polyethylene. In this study, some different formulations based on starch and urea for making polyethylenes which are biodegradable in soil and moist media, have been investigated. The compounds produced are injection molded, and tested under natural conditions and their biodegradability has been studied. It has been thus possible to produce a biodegradable low-density polyethylene which is environmentally biodegradable material that is suitable for agriculture and packaging applications

Application of WSBM Model in Zayanderood Basin (Isfahan)

Water scarcity and salinization are major threats to sustainable irrigation in Iran as well as other parts of the world. Irrigation schemes are part of a basin and as such, irrigation research must be conducted in a basin context. For the Zayanderood basin in central Iran, a simplified Water and Salinity Basin Model (WSBM) was developed for a quick analysis of river basin processes. The model was calibrated and used for current and past water resources analyses. Despite the simplicity of the model, observed and simulated stream flows were similar, proving that the model could be used for scenario analyses. The first scenario was defined where the effect of an increase of water extraction for Isfahan was evaluated. In terms of basin scale water quantity aspects this increased extraction is negligible as extractions are relatively low and return flows are high. A second scenario was developed to study the additional releases required from the reservoir to provide sufficient water for expansion of the Rudashtain irrigation scheme. If no restriction is imposed on water quality, additional releases from the reservoir are limited. However, if salinity levels are not to exceed 2ds m-1, mean annual water release requirements from the reservoir will increase from 52 to 64 m3 s-1, and peak requirements during the irrigation season will increase from 85 to 112 m3 s-1. Finally, it was concluded that the methodology and the model developed were useful for a swift and transparent analysis of past, current and future water and salt resources, and performing scenario analyses

Application of EMC-J criterion to fracture prediction of U-notched polymeric specimens with nonlinear behaviour

The main purpose of the present research paper is to investigate applicability of a new energy‐based failure prediction model, called EMC‐J criterion, to predict the critical loads of U‐notched polymeric samples having a ductile behaviour and loaded under symmetric 3‐point bending. The evaluated polymeric single edge notch bending samples containing U‐notches failed by considerable plastic deformations around the notch border, making it inappropriate to directly use classic linear elastic‐based formulations. Due to the elastic‐plastic behaviour of the tested polymeric material, EMC‐J criterion is applied to avoid using complex and extremely time‐consuming nonlinear analysis for failure load predictions. Finally, it is shown that EMC‐J criterion can provide a good consistency between the experimental and theoretical results with an average discrepancy of about 10%

Development of a plasma panel test for detection of human myocardial proteins by capillary immunoassay

A chemiluminescence inummoassay for the detection of four heart marker proteins: myoglobin, creatine kinase mb [CKmb], troponin I [Tnl], and fatty acid-binding protein [FABP], was designed. The inummoassay was based on enzyme-linked immunosorbent assay [ELISA] and antibodies immobilized in glass capillaries pre-treated with 3-aminopropyltriethoxysilane. The protein bound to the antibody was detected by using an antiprotein-horseradish peroxidase [HR-P] conjugate. The reaction of the HRP with luminal and hydrogen peroxide-based substrate generated the chemiluminescence and a photodiode detector was used to measure the light intensity. The same assay protocol was used to detect all four proteins. Ultrasound waves were used to improve the silanization of glass and the antibody immobilization process. The optimization of the duration and intensity of the ultrasound was performed for the myoglobin assay. Ultrasound improved the silanization procedure and the capillaries gave an approximately 2.5 times greater ELISA response. Ultrasound also improved the sensitivity by approximately 100% when monoclonal antibody was immobilized on a glass capillary. Calibration curves corresponding to analyte concentrations ranging from 2.4 to 2400 ng/ml in plasma samples were recorded. The detection limits were in the region of 1.2 myoglobin, 0.6 CKmb, 5.6 TnI, and 4 ng/ml FABP in plasma with a coefficient of variation of 3-9.9%. (c) 2006 Elsevier B.V. All rights reserved

Decreasing Asphaltene Precipitation and Deposition during Immiscible Gas Injection Via the Introduction of a CO2-Soluble Asphaltene Inhibitor

In this study, the ability of dilute concentrations of toluene to act as a CO2-soluble asphaltene stabilization agent capable of inhibiting asphaltene precipitation during immiscible CO2 injection was assessed. Phase behavior results indicated that 1,000 to 20,000 ppm toluene could readily dissolve in CO2 at cloudpoint pressures that are well below the formation pressure and typical CO2 minimum miscibility pressure (MMP) values during gas-based enhanced oil recovery (EOR). Single-phase solutions of the modified gas (CO2/toluene) were then combined with asphaltenic oils in oil swelling phase behavior tests to demonstrate that the presence of toluene increased the amount of CO2 that dissolved into reservoir crude oil at a specified temperature and pressure. However, asphaltene precipitation diminished, apparently because the effect of the increased asphaltene solvent strength of toluene was more significant than the increased amount of CO2 (an asphaltene antisolvent) that entered the oil-rich phase. During the injection of CO2/toluene solution into cores initially saturated with crude oil and brine, compared to the injection of pure CO2, asphaltene deposition declined during the injection of CO2/toluene mixtures for asphaltenic volatile and intermediate oils from 3.7 wt% to 0.7 wt% and 5.9 wt% to 1.7 wt%, respectively. Based on the asphaltene particle-size analysis, the CO2/toluene mixtures can stabilize oil particles and simultaneously reduce asphaltene aggregation more effectively than pure CO2

ELISA on a microchip with a photodiode for detection of amphetamine in plasma and urine

A rapid and sensitive assay was developed for the detection of amphetamine in plasma and urine. The method relies on the principle of competitive ELISA (enzyme-linked immunosorbent assay). A flow microchip with a total volume of 7 µL was used for the development of a chemiluminescent ELISA technique. Solutions, samples, and the chemiluminescence substrate were injected by a flow system, and a photodiode detector was used to measure the light intensity. The incubation time of the competitor (competition phase) was reduced to 10 min. Calibration curves corresponding to analyte concentrations ranging from 40 to 1000 µg/L in urine samples and from 6 to 96 µg/L in plasma samples were obtained. The detection limits were in the region of 20 and 6 µg/L in urine and plasma, respectively. The main focus of the work was on speed, reliability, reproducibility, and operational stability of the assay. This method was proven readily adaptable to automation and provided reproducible results

Energy-based ductile failure predictions in cracked friction-stir welded joints

This research aims to study the fracture behaviour in dissimilar aluminum alloys adjoined by friction stir welding (FSW). In this way, experimental data dealing with this topic was taken from the recent literature. In those experimental results, two metal sheets made of Al 7075-T6 and Al 6061-T6 were adjoined together by FSW in the form of well-known specimen, namely the cracked semi-circular bend (CSCB) and then they are tested under mixed mode I/II loading condition. Due to the fact that substantial plastic behavior exist in the welded material and consequently significant plastic deformations were observed around the crack tip, failure prediction of the mentioned specimens needs failure prediction models in the basis of the elastic-plastic fracture mechanics which can be realized as sophisticated operations inquiring long time. In this way, the Equivalent Material Concept (EMC) is utilized in this research and then coupled with two eligible energy-based criteria, namely the averaged strain energy density (ASED) and J-integral criteria. Thus, the critical failure load of the welded samples is predicted. Comparison between the empirical data and theoretical predictions from energy-based evaluations showed that this model has enough capability in estimating the critical failure load of the CSCB samples