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Extinction of threat memory is a measure of behavioral flexibility. In the absence of additional reinforcement, the extinction of learned behaviors allows animals and humans to adapt to their changing environment. Extinction mechanisms and their therapeutic implications for maladaptive learning have been extensively studied. However, how aging affects extinction learning is much less understood. Using a rat model of olfactory threat extinction, we show that the extinction of olfactory threat memory is impaired in aged Sprague-Darley rats. Following extinction training, long-term depression (LTD) in the piriform cortex (PC) was inducible ex vivo in aged rats and was NMDA receptor (NMDAR)-independent. On the other hand, adult rats acquired successful olfactory threat extinction, and LTD was not inducible following extinction training. Neuronal cFos activation in the posterior PC correlated with learning and extinction performance in rats. NMDAR blockade either systemically or locally in the PC during extinction training prevented successful extinction in adult rats, following which NMDAR-dependent LTD became inducible ex vivo. This suggests that extinction learning employs NMDAR-dependent LTD mechanisms in the PC of adult rats, thus occluding further LTD induction ex vivo. The rescue of olfactory threat extinction in aged rats by D-cycloserine, a partial NMDAR agonist, suggests that the impairment in olfactory threat extinction of aged animals may relate to NMDAR hypofunctioning and a lack of NMDAR-dependent LTD. These findings are consistent with an age-related switch from NMDAR-dependent to NMDAR-independent LTD in the PC. Optimizing NMDAR function in sensory cortices may improve learning and flexible behavior in the aged population. [ABSTRACT FROM AUTHOR]

[Display omitted] The dynamics of gas–liquid interfaces differs between aqueous surfactant and nanoparticle mixtures in rectangular cross-section capillaries. We designed and fabricated a new microfluidic device with a meter-long channel and a noncircular cross section (35 μm by 100 μm by 1 m) to study the flow behavior of long bubbles in capillaries wetted by water as well as surfactant and nanoparticle solutions. Flow in the novel symmetric loop device maintains essentially straight and inertialess conditions over a wide range of flow rates. The pressure-drop versus velocity relationship of long bubbles in capillaries with noncircular cross sections has been studied theoretically but not extensively validated. The measured pressure drop (normalized with respect to interfacial properties) experienced by bubbles varies as C a 2 / 3 over the range 10 - 7 < C a < 10 - 4 where Ca = μ U σ. Thus, the drag also scales as C a 2 / 3 . The measurements from our new device thereby confirm previous theoretical relationships of the flow of long gas bubbles wetted by surfactant solutions in noncircular capillaries. Contrary to the hypothesis, the C a 2 / 3 drag–velocity relationship applies to gas bubbles in deionized water, nanoparticles in brine, surfactant in brine, and nanoparticle-surfactant mixtures in brine for the conditions studied. [ABSTRACT FROM AUTHOR]

We designed and fabricated a new microfluidic device to better enable study of foam microstructure and rheology in planar fractures. The design phase included stress–strain finite element analysis to enhance the pressure tolerance of the device. The optimized design is a 2 cm wide by 7.75 cm long rough fracture that includes 25 posts to anchor the glass cover plate. The posts simulate asperities and provide structural support during bonding of a glass cover plate to the device. Importantly, the new design illustrates improved ability to sustain large differential pressure compared to previous designs in the literature. The rheometer permits study of the relationship among foam bubble morphology, pressure drop, and flow rates. Our findings validated the previous, sparse microvisual studies mentioned in the literature and confirmed that small quality foam, ranging from 20 to 50% gas by volume, contains dispersed bubbles separated by liquid lenses. In this range, the distribution of bubble sizes was roughly 80–90% small uniform bubbles and only 10–20% of larger and more elongated bubbles. Additionally, our studies reveal that foam apparent viscosity is a strong function of foam quality, velocity, and texture (i.e., bubble size). Apparent viscosity of foam ranged from 100 to 600 cP for the conditions studied. High quality foams in fractures are independent of gas flow rates but very sensitive to liquid flow rates. On the other hand, low quality foams are sensitive to gas flow rates but independent of liquid flow rates. [ABSTRACT FROM AUTHOR]

Despite the increasing interest in CO2 foam flooding for enhanced oil recovery applications, it is challenging to have a successful field operation as the performance of the surfactant is often affected by the presence of crude oil and salinity of the water. It is also challenging to dispose of huge amounts of water associated with the field operation. Due to the incompatibility of the produced water with chemicals used in the foam system, the produced water cannot be used as an injecting fluid. The objective of this project is to design a chemical system compatible with produced water which may fully utilize the oil field produced water as an injecting fluid and make the foam injection economically viable and environmentally friendly. In this study, we investigate the performance of a foam system with a surfactant and the addition of polyelectrolyte and polyelectrolyte complex nanoparticles (PECNP) in various salinities of produced water. A recipe is developed to prepare a nanoparticle solution that is sustainable in high salinity produced water. The rheological property of the foam, the stability, and durability of the foam with and without the presence of crude oil are measured and compared as the water salinity is changed. It is found that foam stability and durability deteriorated when water salinity increased. However, by the addition of polyelectrolyte and PECNP in the system, the foam stability and durability was improved even in high salinity water with or without the presence of crude oil. [ABSTRACT FROM AUTHOR]

Geologic heterogeneity is one of the important factors controlling migration and distribution of nonaqueous phase liquids in the subsurface. Heterogeneity, such as fractures, complicates the effectiveness of environmental remediation, and uncharacterized aquifer heterogeneity causes significant uncertainties in the removal of nonaqueous phase liquids. Foaming an injection gas is an effective method to alleviate the challenges in accessing heterogeneous media during remediation processes because foam is nonNewtonian and redirects gas and liquid flow. Foamed gas may also assist in increasing the storage of carbon dioxide in saline formations. This paper investigates foam flow behavior in microscale fractures and develops a mechanistic transient foam flow model using the population balance method. Microscale experiments in fractures with apertures of 25 and 88 μ m are used to validate the model for pressure drop, gas saturation, and bubble texture. Key differences related to modeling foam in fractures are the potential for continuously varying gas–liquid curvature in fractures and the relationship of this curvature to apparent foam viscosity. Incorporation of a local foam flow resistance factor is important to representing flow physics accurately. Hence, the results of this study provide foundational understanding for upscaling foam rheology in different sized fractures to ensure successful operations in soil/aquifer remediation and CO 2 storage in saline formations. • Foam is effective at controlling gas mobility in fractures. • Population balance simulation approach extended to foam in fractures. • The underlying physics of foam generation, coalescence, and transport are similar in fractured and unfractured media. • Nevertheless, model equations need to be modified for foam flow in fractures. [ABSTRACT FROM AUTHOR]

Low salinity water injection (LSWI) is the process of injecting modified salinity brine with controlled ionic composition to achieve increased oil recovery compared to conventional waterflooding. This paper reviews the most recent advances in proposed low salinity mechanisms, but specifically emphasizes the role of thin liquid films in crude oil/brine/rock systems. Importantly, thin water films on rock surfaces affect hydraulic resistance of pore channels as well as phase-trapping mechanisms. As films become thicker, they provide greater lubrication of oil droplets and hence, flow resistance decreases. Consequently, films dictate oil and water distribution in porous media and determine the wettability of crude oil/brine/rock systems under static and dynamic conditions. The stability of the thin water films depends on the interactions between the oil/brine and the calcite/brine interfaces through van der Waals, electrostatic, and structural forces. Image 1 [ABSTRACT FROM AUTHOR]

Enhanced oil recovery with scCO 2 foam fluids stabilized by PECNP/Surfactant at the lamella interface helps to store and sequester CO 2 in underground formations. The presented mixture reduces the amount of fresh water usage and produced water disposal in EOR process. • PECNP improved CO 2 foam stability for EOR applications. • The stabilized foam reduced produced water disposal and freshwater usage for EOR. • Raman spectroscopy proved ionic complexation of surfactant and PECNP. • Ionic complexation improved the foam sweep efficiency and oil recovery. CO 2 foam flooding is a proven technology that enhances oil recovery and geological storage by improving the mobility of the injected CO 2 in depleted reservoirs. Surfactant drainage, disintegration and rock adsorption have long affected the stability of CO 2 foams in saline formations. To generate a more stable foam front in the presence of crude oil and to overcome the capillary forces destabilizing the foam lamella, polyelectrolyte complex nanoparticles (PECNP) conjugated with surfactant oligomers are introduced to the lamella generated by an aqueous phase containing high salinity to improve the EOR performance and produced water compatibility of supercritical CO 2 (scCO 2) foams. The formation of vesicular structures containing electrostatically hinged complexes of PECNP and surfactant was verified via transmission electron microscopy (TEM) while the structural changes associated with molecular complexation were identified using Raman spectroscopy. Accordingly, optimized ratios of PECNP:surfactant were employed to generate the most stable scCO 2 foam in high salinity produced water and improve the recovery of the foam flooding process. The effect of PECNP-conjugated surfactant on stability, durability, and interfacial properties of scCO 2 foam were examined. A set of core-flooding experiments in a wide range of salinity proved the capability of scCO 2 foam systems enhanced using PECNP-surfactant to offer the highest apparent viscosity and incremental oil recovery. A variety of injection scenarios tested on oil-saturated limestone core samples indicating that the highest incremental oil recovery and the lowest residual oil saturation are achieved by prioritizing PECNP:surfactatnt scCO 2 foam flood in optimized electrolyte concentrations. [ABSTRACT FROM AUTHOR]

The purpose of our study was to extend tenets of objectification theory to a sample of 278 undergraduate African American women. We hypothesized that internalized multiculturally inclusive racial identity attitudes would moderate the relationship between sexually objectifying experiences and internalized sociocultural standards of beauty, which would then correlate with less body surveillance. In turn, we predicted that less body surveillance would be associated with less body shame, appearance anxiety, and greater interoceptive awareness, which would likely be associated with decreased eating disordered behaviors. A moderated mediation analysis supported the overall model, suggesting that internalized multiculturally inclusive racial identity attitudes buffer against sexually objectifying experiences. When sexually objectifying experiences were high and internalized multiculturally inclusive racial identity attitudes were low, participants were more likely to internalize dominant standards of beauty, which was then associated with increased body surveillance, body shame, appearance anxiety, disordered eating, and poorer interoceptive awareness. Interventions aimed to assist African American women develop a positive race salience and challenge sociocultural standards of beauty seem warranted in order to diminish body image concerns and disordered eating. [ABSTRACT FROM PUBLISHER]

The purpose of our study was to investigate African American women’s experiences with sexual objectification. Utilizing grounded theory methodology as well as Black feminist thought and objectification theory as the research lenses, the results of this study uncovered how racist, sexist, and classist ideologies contributed to sexual objectification experiences (SOEs) among African American women. Twenty African American female graduate students and others recruited from a campus community participated in semistructured interviews. Data revealed a number of different sociocultural factors that contributed to the sexual objectification of African American women (i.e., historical influence of slavery, sexualized views and images of African American women, and patriarchal social structure). These factors were observed to contribute to different forms of sexual objectification, ranging from comments and objectifying gazes to more extreme forms, such as sexual abuse. Participants described a number of effects of sexual objectification, including self-objectification, physical safety anxiety, eating concerns, psychological/emotional, and interpersonal. Participants also described how they coped with and grew from these experiences. Psychologists and mental health professionals are encouraged to consider how African American women’s SOEs are rooted in racism, sexism, and classism. Furthermore, these practitioners are urged to develop an awareness of how these oppressions intersect and contribute to the sexual objectification of African American women. [ABSTRACT FROM PUBLISHER]