Presence Of C6 Research Articles

Coinjection of C6, C7, and CO2 with steam to improve low-pressure SAGD process

Steam assisted gravity drainage (SAGD) is one of the most widely used processes of thermal recovery for heavy oil. Investigating the effectiveness of solvent coinjection with steam is an important aspect in the optimisation of SAGD process. So far, however, the effects of using CO2 have not been closely examined. This study sheds light on the addition of hydrocarbon solvents with CO2 which reached earlier maximum ultimate oil recovery (90%) than that for other solvents coinjection. This study shows that solubility of C6, heat loss reduction and CO2 diffusion, are the main recovery mechanism in enhancing oil recovery. The present study highlights the steam propagation in the presence of C6 and CO2 and its relation to enhancing oil recovery. It is interesting to observe that physical properties of the injected fluid reduce the energy consumption. Another finding is that solvent coinjection leads to stable subcool, hence increase oil recovery.

Cytotoxicity and cellular uptake of perfluorocarboxylic acids

Abstract To address the health and environmental concerns associated with perfluorocarboxylic acids, the assessment of cytotoxicity and bioaccumulation of perfluorocarboxylic acids is essential. This study investigated the effect of perfluorocarboxylic acids having various chain lengths on mouse melanoma B16 cells. The extent of cytotoxicity of perfluorohexanoic acid (C6), perfluoroheptanoic acid (C7), perfluorooctanoic acid (C8), perfluorononanoic acid (C9) and perfluorodecanoic acid (C10) within a concentration range of 0.25–1600 μg/ml was determined. Based on results, the viability of cells was 90% or higher in the presence of C6, C7, C8 at a concentration of up to 200 μg/ml, indicating that B16 cells are safe in the presence of C6, C7 and C8. On the other hand, moderate cytotoxicity was observed with C9 or C10, even at a relatively low concentration of 25 μg/ml. When cells were incubated in the presence of the same concentration (100 or 200 μg/ml) of perfluorocarboxylic acids, the number of live cells decreased as the perfluoroalkyl chain length increased suggesting that long-chained perfluorocarboxylic acids are more cytotoxic than short-chained perfluorocarboxylic acids. The correlation between cellular uptake and perfluoroalkyl chain length was also investigated. The presence of C6 in the cells was not detected probably because of poor uptake. On the other hand, the presence of C7–C10 in the cells was confirmed and quantified by LC ESI MS. Results showed that cellular uptake of long-chained perfluorocarboxylic acids were significantly higher than short-chained perfluorocarboxylic acids.

Ultrasmall Black Phosphorus Quantum Dots: Synthesis and Use as Photothermal Agents.

Black phosphorus quantum dots (BPQDs) were synthesized using a liquid exfoliation method that combined probe sonication and bath sonication. With a lateral size of approximately 2.6 nm and a thickness of about 1.5 nm, the ultrasmall BPQDs exhibited an excellent NIR photothermal performance with a large extinction coefficient of 14.8 L g(-1) cm(-1) at 808 nm, a photothermal conversion efficiency of 28.4%, as well as good photostability. After PEG conjugation, the BPQDs showed enhanced stability in physiological medium, and there was no observable toxicity to different types of cells. NIR photoexcitation of the BPQDs in the presence of C6 and MCF7 cancer cells led to significant cell death, suggesting that the nanoparticles have large potential as photothermal agents.

Ultrasmall Black Phosphorus Quantum Dots: Synthesis and Use as Photothermal Agents

AbstractBlack phosphorus quantum dots (BPQDs) were synthesized using a liquid exfoliation method that combined probe sonication and bath sonication. With a lateral size of approximately 2.6 nm and a thickness of about 1.5 nm, the ultrasmall BPQDs exhibited an excellent NIR photothermal performance with a large extinction coefficient of 14.8 Lg−1 cm−1 at 808 nm, a photothermal conversion efficiency of 28.4 %, as well as good photostability. After PEG conjugation, the BPQDs showed enhanced stability in physiological medium, and there was no observable toxicity to different types of cells. NIR photoexcitation of the BPQDs in the presence of C6 and MCF7 cancer cells led to significant cell death, suggesting that the nanoparticles have large potential as photothermal agents.

In vitro anti-nitrosative, antioxidant, and cytotoxicity activities of plant flavonoids: a comparative study

The ability of eight flavonoids to react with the biologically relevant reactive nitrogen species, nitric oxide, peroxynitrite, and nitrous acid were investigated in vitro, for the first time. All the investigated flavonoids were found to be potent reactive nitrogen and oxygen species scavengers and resulted in a significant inhibition of 3-nitrotyrosine (3-NT) formation in a dose-dependent manner. All the IC50s were found at the μM level. The results reveal that, the presence of C5–OH and C4’–OH, in the flavonoid skeleton, enhanced the anti-nitrosative activity. The absence of the C2=C3 double bond and/or C4-carbonyl group resulted in slight decrease of the anti-nitrosative activity. However, the presence of C6- and/or C3’-methoxy groups together with C4’–OH dramatically decrease the inhibition capacity. Especially the free hydroxyl groups at 3’ and 4’ of the catechol containing ring B flavonoids as well as both hydroxyl groups at C3 and C5 are necessary for better antioxidant activity. The absence of both C3–OH and/or C3’–OH groups resulted in a remarkable decrease in the antioxidant activity. The cytotoxicity results indicate that the investigated flavonoids are safe to be used up to a concentration of 100 μM and may be utilized as promising sources of therapeutics.

Possible involvement of ceramide in the regulation of rat Leydig cell function

In the present study, a possible role of a ceramide-dependent pathway in the regulation of Leydig cell function was investigated. Intracellular ceramide levels were increased by: (a) adding ceramide analogs; (b) inhibiting ceramidase activity; and (c) adding sphingomyelinase (SMase). The cell-permeable ceramide analogs N-acetyl-, N-hexanoyl- and N-octanoylsphingosine (C2, C6 and C8) were used. As inhibitor of ceramidase activity 1 S,2 R- d-erythro-2-( N-myristoylamino)-1-phenyl-1-propanol (MAPP) was used. Shingomyelinase from S. aureus origin was utilized. Leydig cells were cultured for 3 or 24 h with or without the different drugs (10 μM) and SMase (0.3 U/ml) in the presence or absence of hCG (10 ng/ml). Basal testosterone production was not modified under any of the experimental conditions. A decrease in hCG-stimulated testosterone production was observed at 3 and 24 h in all cases. The inactive analog ( N-hexanoyl dihydrosphingosine) did not produce inhibition in hCG-stimulated testosterone production. TNFα and IL1β, two possible inducers of sphingomyelin hydrolysis, produced similar effects on hCG-stimulated testosterone production. In experiments performed in the presence of C6, inhibition in hCG-stimulated cAMP production was observed. The inhibitory effect of ceramide was also observed in dbcAMP-stimulated cultures indicating that this pathway inhibits post-cAMP formation events. To study possible loci for the action of ceramide on the steroidogenic pathway, cells were incubated with C6 and MAPP in the presence of different testosterone precursors. The drugs inhibited testosterone produced from 22( R)-hydroxycholesterol (22 R-OHChol), pregnenolone and 17α-hydroxyprogesterone (17OHP4) but not from androstenedione (Δ4). These results suggest that a ceramide-dependent pathway regulates hCG-stimulated Leydig cell steroidogenesis at the level of cAMP production and at post-cAMP events.

Interactions between Human C5, C6, and C7 and Their Functional Significance in Complement-Dependent Cytolysis

Abstract Two types of complexes were observed between C5, C6 and C7. In their native form these three complement proteins enter into reversible interactions which were demonstrated by zone ultracentrifugation. Interactions between C5 and C6 occurred in absence of C7 and between C5 and C7 in absence of C6. Presence of C6, however, enhanced the association of C5 and C7. Formation of a stable C5–C6 complex was effected by the complement enzyme . This complex () had a sedimentation coefficient of 12 to 14S and exhibited the ability to attach itself firmly to non-sensitized sheep erythrocytes (E) in presence of C7. activity was also generated by trypsin or plasmin, suggesting the existence of a new pathway of complement activation by non-complement enzymes beginning with C5. produced with trypsin or displayed typical ultrastructural membrane lesions and was susceptible to lysis by C8 and C9. Regardless of experimental conditions, C5, C6, and C7 were taken up by the surface of cells in equimolar quantities. The affinity between native C5, C6, and C7 displayed in free solution, and the equimolarity of the cell-bound equivalents, support the concept of a firm trimolecular assembly as the topologic base of the membrane attack mechanism of complement.