ENGINEERING OF POLYMERS TO THICKEN CARBON DIOXIDE: A SYSTEMATIC APPROACH

Carbon dioxide (CO2) is one of the potential displacing fluids used in Enhanced Oil Recovery (EOR). However, the effective use of CO2 in EOR is hindered by its low viscosity, resulting in CO2 to "finger" towards production well and thus low sweep efficiency. The current research has aimed to bring the viscosity of CO2 to a level comparable to that of oil via dissolution of polymeric materials (thickeners) to suppress early breakthrough of CO2 in EOR. A series of fluoroacrylate-aromatic acrylate copolymers was designed and tested for their miscibility and viscosity enhancement in CO2 at 295 K. The change in the series was created by changing either the spacer length or the size of aromatic rings in the aromatic acrylate unit of the copolymer. Aforementioned copolymers were found to be highly miscible with CO2 and to impart enhancement in the viscosity of CO2, depending on the type and content of the aromatic acrylate unit in the copolymer. Increase in the viscosity was attributed to association of aromatic rings by stacking. Feasibility of EOR process depends also on the factors associated with economic and environmental issues. The current research, therefore, also aimed to explore the generation of low-cost, non-fluorous polymers to replace high cost fluoroacrylate moiety. The polymers were designed hypothesizing that a CO2-philic polymer should posses inherently low cohesive energy density, low glass transition temperature (i.e. high chain flexibility and free volume) and a number of Lewis base groups to promote cross interactions with CO2. Polymers were prepared, where possible, via modification of an existing polymer with a precursor containing Lewis base group to eliminate the effect of chain length on the phase behavior. Modifications were performed basically on silicone, polyether or hydrocarbon backbone (vinyl and allyl). The phase behavior results showed that there is a delicate balance between the forces working to increase the miscibility pressures (e.g. high cohesive energy density) or factors suppressing the entropy of mixing, and those working to lower miscibility pressures, such as enhanced specific interactions with CO2 and increased free volume or chain flexibility

Impaired IL-23-dependent induction of IFN-gamma underlies mycobacterial disease in patients with inherited TYK2 deficiency

Human cells homozygous for rare loss-of-expression (LOE) TYK2 alleles have impaired, but not abolished, cellular responses to IFN-alpha/beta (underlying viral diseases in the patients) and to IL-12 and IL-23 (underlying mycobacterial diseases). Cells homozygous for the common P1104A TYK2 allele have selectively impaired responses to IL-23 (underlying isolated mycobacterial disease). We report three new forms of TYK2 deficiency in six patients from five families homozygous for rare TYK2 alleles (R864C, G996R, G634E, or G1010D) or compound heterozygous for P1104A and a rare allele (A928V). All these missense alleles encode detectable proteins. The R864C and G1010D alleles are hypomorphic and loss-of-function (LOF), respectively, across signaling pathways. By contrast, hypomorphic G996R, G634E, and A928V mutations selectively impair responses to IL-23, like P1104A. Impairment of the IL-23-dependent induction of IFN-gamma is the only mechanism of mycobacterial disease common to patients with complete TYK2 deficiency with or without TYK2 expression, partial TYK2 deficiency across signaling pathways, or rare or common partial TYK2 deficiency specific for IL-23 signaling.ANRS Nord-Sud ; CIBSS ; CODI ; Comité para el Desarrollo de la Investigación ; Fulbright Future Scholarshi

The cultural construction of Alevi female identity

© 2002 Dr. Sevgi KilicAnthropologists have discussed extensively issues relating to the relationship between the researcher and the researched community (Abu-Lughod,1988; Bourdieu, 1977; Macintyre, 1990; Dwyer, 1982; Visweswaran, 1996; Shankland, 1996; Moore, 1988; Haraway, 1991) and how this relationship influences the way the data is collected and interpreted. They have increasingly questioned and criticised the notion of absolute objectivity (Ram, 1991) of their own field data. As Rabinow observes, the "data we collect is doubly mediated, first by our own presence and then by the second order reflection we demand from our informants" (1977: 119). Subjectivity is part of the anthropologist's fieldwork experience and is highlighted in the complexities involved in being an ‘insider’ or ‘outsider’ to the research community. The issue of being insider and ‘outsider’ is highly contentious amongst anthropologists. Indigenous anthropologists have argued that their familiarity with the culture enables them to attribute meaning to the social practices of the people they study more readily and accurately than the non-indigenous researcher can. Indigenous researchers, they argue, share the same social and cultural world as their subjects, thereby ensuring that they can interpret things more readily. While there are some obvious advantages in being an 'insider' there are also some complex issues which they encounter that an 'outsider' would not experience. The ‘outsiders’ are able to maintain a social distance with the researched community that 'insiders' perhaps could find difficult (Cassell, 1977). Indigenous insiders can often be in a position where they assume and take certain practices as a given and fail to analyse or document those experiences which they share with the community. While the ability to speak the language of the research community is an invaluable asset this does not exclude indigenous anthropologists from overlooking or even misconstruing the nuances of language (Spradley, 1979) and may mean that they take for granted linguistic peculiarities

Contributory roles of concentration and pH in CaCO3 growth inhibition by additive Ca2+ ions

CaCO3 particles grow excessively upon chemical precipitation in the absence of impurities or growth inhibitors. Additive Ca2+ ions have been shown to preferentially adsorb on CaCO3 precipitates, effectively inhibiting their growth and promoting the crystallization of pure calcite without an observable intermediate phase. This phenomenon can be adapted towards the synthesis of small calcite particles from a conventional chemical precipitation method. Complementing such effort, this study discusses the influence of additive Ca2+ ions concentration and solution pH on the extent of CaCO3 growth inhibition. Equal volumes of equimolar CaCl2 and Na2CO3 solutions were mixed in a tubular reactor at a constant flowrate. The precipitates were continuously dispersed in Ca(OH)2 solution, where Ca2+ ions irreversibly adsorb on their surfaces. Compared to conditions where additive Ca2+ ions are absent, this method can produce more than 90% decrease in particle size. The results show the degree of growth inhibition increases as the concentration of additive Ca2+ ions increase. However, it is limited by increasing volume of precipitates. This study also reveals an unusual role of media pH. Here, growth inhibition that leads to the synthesis of monodisperse submicron CaCO3 particles is only observed in high alkaline pH conditions. This is due to the hydration of additive Ca2+ ions in low pH conditions. While additive Ca2+ ions adsorb on CaCO3 precipitates in pH conditions above the isoelectric point (pH ≈ 9), their ability to limit CaCO3 growth diminishes when pH < 12

Neuropeptide-Y, leptin and ghrelin levels in children with ADHD: effects of methylphenidate treatment

Objective: This study aims to evaluate the plasma levels of neuropeptide-Y (NPY), leptin and ghrelin and in children with attention deficit hyperactivity disorder (ADHD) and investigate the neurobiological mechanisms beneath side effects of methylphenidate such as lack of appetite, weight loss and/or decrease in weight gain. Methods: Thirty children diagnosed as ADHD with DSM-5 and 21 healthy children similar to study group with age and gender were included in the study. All subjects are evaluated with Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL). All parents filled sociodemographic data form, also parents of the children with ADHD filled Conners' Parent Rating Scale (CPRS). ADHD group evaluated with Barkley Stimulant Side Effect Evaluation Form after two months of extended release methylphenidate (OROS-MPH) therapy. Plasma NPY, leptin and ghrelin levels were evaluated in control group for once and in ADHD group for twice, before and 2 months after treatment with enzyme-like immune-sorbent assay (ELISA) kits. Results: In our study, when plasma leptin, ghrelin and NPY levels of healthy controls and ADHD group were compared; NPY level was lower in the ADHD group. Compared with healthy controls, post-treatment ADHD group leptin level was observed to be lower. In the ADHD group, only NPY level was found to be higher after treatment than before treatment. Conclusion: It was observed that NPY levels were found to be lower in the ADHD group than in the healthy group, and plasma levels increased after treatment. In addition, leptin and ghrelin levels not changed after treatment. Thus, further studies with larger study groups are needed whether these changes will be more meaningful when the treatment duration is prolonged. New studies may reveal neurobiological mechanisms beneath loss of appetite and/or weight loss associated with methylphenidate treatment

Evaluation of Liposomal and Microbubbles Mediated Delivery of Doxorubicin in Two-Dimensional (2D) and Three-Dimensional (3D) Models for Breast Cancer

Objective: Liposomal cancer treatment strategies are useful in removing the side effects that were the main concern in recent years. In this study, we prepared microbubble (MBs) conjugated with DOX-loaded liposomes (DOX-loaded MBs) and investigated their effectiveness in in vitro breast cancer cells in two dimensions (2D) and three dimensions (3D)