Desorption of hydrocarbon chains by association with ionic and nonionic surfactants under flow as a mechanism for enhanced oil recovery

The need to extract oil from wells where it is embedded on the surfaces of rocks has led to the development of new and improved enhanced oil recovery techniques. One of those is the injection of surfactants with water vapor, which promotes desorption of oil that can then be extracted using pumps, as the surfactants encapsulate the oil in foams. However, the mechanisms that lead to the optimal desorption of oil and the best type of surfactants to carry out desorption are not well known yet, which warrants the need to carry out basic research on this topic. In this work, we report non equilibrium dissipative particle dynamics simulations of model surfactants and oil molecules adsorbed on surfaces, with the purpose of studying the efficiency of the surfactants to desorb hydrocarbon chains, that are found adsorbed over flat surfaces. The model surfactants studied correspond to nonionic and cationic surfactants, and the hydrocarbon desorption is studied as a function of surfactant concentration under increasing Poiseuille flow. We obtain various hydrocarbon desorption isotherms for every model of surfactant proposed, under flow. Nonionic surfactants are found to be the most effective to desorb oil and the mechanisms that lead to this phenomenon are presented and discussed.Comment: 10 figures; to appear in Scientific Report

Freshwater Crustaceans Decadpos: An Important Resource of Guatemala

Guatemala is a mega diversity country because it has several ecosystems and the physiography has a high diversity. However, the local population uses this biodiversity as a natural resource of food mainly. The country had three main drainage slopes for their rivers and aquatic reservoirs with several basins (the Gulf of Mexico, the Caribbean Sea, and the Pacific Sea). In these slopes, crayfish, freshwater prawns, and crabs compose the aquatic biological resources. Several fieldtrips were performed around these slopes in order to identify the species which were used as natural aquatic resources and verify if the diversity supports the food needs of the local population. Our findings were that the country has at least four crayfish species of genus Procambarus spp., those living in the high and middle altitude areas. Five freshwater prawn species with abbreviated larval development of genus Macrobrachium, that is, Macrobrachium cemai were also found. The bigger species of Macrobrachium was also identified on the three slopes as Macrobrachium americanum, Macrobrachium tenellum, Macrobrachium occidentale, and Macrobrachium digueti on the Pacific slope, while on the Gulf of Mexico and the Caribbean Sea, Macrobrachium carcinus, Macrobrachium acanthurus, Macrobrachium heterochirus, Macrobrachium olfersii, and Macrobrachium hobbsi were recorded, and therefore, the nonnative species Macrobrachium rosenbergii; with respect to other shrimps, Palaemon pandaliformis, Palaemonetes octaviae, and atyids as Atya scabra and Potimirim glabra were found. According to the freshwater crabs, the Pseudothelphusidae family is the best to represent in comparison with Trichodactylidae where only one population was recorded. Also, we register the uses of these species around the main markets in the country and we found two main ways: the first one is for the bigger species of freshwater prawns and crabs that are offered very expensive in kilogram and are almost offered in restaurants as exclusive dishes. The second one is more for the local consumption, and many families of fishery species that include crayfishes, freshwater prawns with abbreviated larval development, and smaller crabs, and so on, are sometimes found in the markets, with the prices being cheaper and can be bought only by the local people. Our findings show that Guatemala has an enormous potential in the crustaceans decapods for use as natural aquatic resources as protein sources at low cost, especially for the families with low economical level

Holistic Photoprotection, Broad Spectrum (UVA-UVB), and Biological Effective Protection Factors (BEPFs) from Baccharis antioquensis Hydrolysates Polyphenols

Overexposure to solar radiation has become an increasingly worrying problem due to the damage to the skin caused by ultraviolet radiation (UVR). In previous studies, the potential of an extract enriched with glycosylated flavonoids from the endemic Colombian high-mountain plant Baccharis antioquensis as a photoprotector and antioxidant was demonstrated. Therefore, in this work we sought to develop a dermocosmetic formulation with broad-spectrum photoprotection from the hydrolysates and purified polyphenols obtained from this species. Hence, the extraction of its polyphenols with different solvents was evaluated, followed by hydrolysis and purification, in addition to the characterization of its main compounds by HPLC–DAD and HPLC–MS, and evaluation of its photoprotective capacity through the measurement of the Sun Protection Factor (SPF), UVA Protection Factor (UVAPF), other Biological Effective Protection Factors (BEPFs), and its safety through the cytotoxicity. In the dry methanolic extract (DME) and purified methanolic extract (PME), flavonoids such as quercetin and kaempferol were found, which demonstrated antiradical capacity, as well as UVA–UVB photoprotection and prevention of harmful biological effects, such as elastosis, photoaging, immunosuppression, DNA damage, among others, which demonstrates the potential of the ingredients in this type of extract to be applied in photoprotection dermocosmetics.The authors acknowledge CODI-Universidad de Antioquia (Project No. CIQF 290) for financial support. The authors would like to thank the International Passages Support Fund Universidad de Antioquia. The research was financed partially by NAZCA Project (P20-00458) by Andalusian Government. Partial funding for open access charge: Universidad de Málag

Living Arrangements and Dementia Among the Oldest Old: A Comparison of Mexicans and Mexican Americans

Background and Objectives The growing population of adults surviving past age 85 in the United States and Mexico raises questions about the living arrangements of the oldest old and those living with dementia. This study compares Mexican and Mexican American individuals aged 85 and older to identify associations with cognitive status and living arrangements in Mexico and the United States. Research Design and Methods This study includes 419 Mexican Americans in 5 southwestern states (Hispanic Established Population for the Epidemiologic Studies of the Elderly) and 687 Mexicans from a nationally representative sample (Mexican Health and Aging Study). It examines characteristics associated with living alone using logistic regression and describes the living arrangements of older adults with probable dementia in each country. Results Older adults with dementia were significantly less likely to live alone than with others in the United States while there were no relationships between dementia and living arrangements in Mexico. However, a substantial proportion of older adults with dementia lived alone in both nations: 22% in the United States and 21% in Mexico. Among Mexican Americans with dementia, those living alone were more likely to be women, childless, reside in assisted living facilities, and less likely to own their homes. Similarly, Mexican individuals with dementia who lived alone were also less likely to be homeowners than those living with others. Discussion and Implications Contextual differences in living arrangements and housing between the United States and Mexico pose different challenges for aging populations with a high prevalence of dementia