Environmental comparative study of biosurfactants production and optimization using bacterial strains isolated from Egyptian oil fields

Biosurfactants have recently gained popularity because they have numerous benefits over chemical synthetic surfactants, including higher biodegradability, lower toxicity, higher foaming, environmental compatibility, and effective properties under harsh conditions. This study aimed to produce effective biosurfactants by selected bacterial strains isolated from Egyptian oil fields to improve oil recovery and investigate their environmental aspects for microbial enhanced oil recovery. The selected strains were incubated in a new proposed nutrient medium H to produce biosurfactants with optimum surface and emulsification activities. Stability studies were conducted to examine the tolerance of produced biosurfactants in harsh reservoir conditions. Core flooding tests were performed to investigate the potential of produced biosurfactants in enhancing oil recovery. The environmental risk assessment was conducted to investigate if there are any possible threats of the selected bacterial strains. Results showed that selected bacterial strains Bacillus licheniformis and Bacillus subtilis could produce effective biosurfactants that reached their maximum surface activity after 24 h of incubation by reducing the surface tension from 71.8 mN/m to 27.13 mN/m and 25.74 mN/m, and the interfacial tension against kerosene from 48.4 mN/m to 1.27 mN/m and 0.38 mN/m at critical micelle concentration of 0.06 g/l and 0.04 g/l, respectively. The produced biosurfactants by Bacillus licheniformis and Bacillus subtilis showed significant emulsification activity against crude oil with emulsification indices of 50.2% and 63.7%, respectively. High stability was observed at high temperatures for a long-time period and more than 60% of their surface and emulsification activities were maintained over a wide range of pH and salinity. It was also found that 31.41–39.35% of additional oil could be recovered by the produced biosurfactants. Finally, Bacillus licheniformis and Bacillus subtilis are environmentally safe, have no potential for toxicity, and no risk could occur for MEOR

Modeling Nonlinear Systems by a Fuzzy Logic Neural Network Using Genetic Algorithms

The main aim of this work is to optimize the parameters of the constrained membership function of the Fuzzy Logic Neural Network (FLNN). The constraints may be an indirect definition of the search ranges for every membership shape forming parameter based on 2nd order fuzzy set specifications. A particular method widely applicable in solving global optimization problems is introduced. This approach uses a Linear Adapted Genetic Algorithm (LAGA) to optimize the FLNN parameters. In this paper the derivation of a 2nd order fuzzy set is performed for a membership function of Gaussian shape, which is assumed for the neuro-fuzzy approach. The explanation of the optimization method is presented in detail on the basis of two examples

DREAM II. The spin-orbit angle distribution of close-in exoplanets under the lens of tides

The spin-orbit angle, or obliquity, is a powerful observational marker that allows us to access the dynamical history of exoplanetary systems. Here, we have examined the distribution of spin-orbit angles for close-in exoplanets and put it in a statistical context of tidal interactions between planets and their stars. We confirm the observed trends between the obliquity and physical quantities directly connected to tides, namely the stellar effective temperature, the planet-to-star mass ratio, and the scaled orbital distance. We further devised a tidal efficiency factor combining critical parameters that control the strength of tidal effects and used it to corroborate the strong link between the spin-orbit angle distribution and tidal interactions. In particular, we developed a readily usable formula to estimate the probability that a system is misaligned, which will prove useful in global population studies. By building a robust statistical framework, we reconstructed the distribution of the three-dimensional spin-orbit angles, allowing for a sample of nearly 200 true obliquities to be analyzed for the first time. This realistic distribution maintains the sky-projected trends, and additionally hints toward a striking pileup of truly aligned systems. The comparison between the full population and a pristine subsample unaffected by tidal interactions suggests that perpendicular architectures are resilient toward tidal realignment, providing evidence that orbital misalignments are sculpted by disruptive dynamical processes that preferentially lead to polar orbits. On the other hand, star-planet interactions seem to efficiently realign or quench the formation of any tilted configuration other than for polar orbits, and in particular for antialigned orbits.Comment: Accepted in A&

The JADE code: Coupling secular exoplanetary dynamics and photo-evaporation

Close-in planets evolve under extreme conditions, raising questions about their origins and current nature. Two predominant mechanisms are orbital migration, which brings them close to their star, and atmospheric escape under the resulting increased irradiation. Yet, their relative roles remain unclear because we lack models that couple the two mechanisms with high precision on secular timescales. To address this need, we developed the JADE code, which simulates the secular atmospheric and dynamical evolution of a planet around its star, and can include the perturbation induced by a distant third body. On the dynamical side, the 3D evolution of the orbit is modeled under stellar and planetary tidal forces, a relativistic correction, and the action of the distant perturber. On the atmospheric side, the vertical structure of the atmosphere is integrated over time based on its thermodynamical properties, inner heating, and the evolving stellar irradiation, which results, in particular, in photo-evaporation. The JADE code is benchmarked on GJ436 b, prototype of evaporating giants on eccentric, misaligned orbits at the edge of the hot Neptunes desert. We confirm that its orbital architecture is well explained by Kozai migration and unveil a strong interplay between its atmospheric and orbital evolution. During the resonance phase, the atmosphere pulsates in tune with the Kozai cycles, which leads to stronger tides and an earlier migration. This triggers a strong evaporation several Gyr after the planet formed, refining the paradigm that mass loss is dominant in the early age of close-in planets. This suggests that the edge of the desert could be formed of warm Neptunes whose evaporation was delayed by migration. It strengthens the importance of coupling atmospheric and dynamical evolution over secular timescales, which the JADE code will allow simulating for a wide range of systems.Comment: 20 pages, 2 figures, accepted in A&

Teaching Synthesis

Students will learn how to synthesize information from sources.https://digitalcommons.csumb.edu/teaching_all/1020/thumbnail.jp

Exploring the Design of mHealth Systems for Health Behavior Change using Mobile Biosensors

A person’s health behavior plays a vital role in mitigating their risk of disease and promoting positive health outcomes. In recent years, mHealth systems have emerged to offer novel approaches for encouraging and supporting users in changing their health behavior. Mobile biosensors represent a promising technology in this regard; that is, sensors that collect physiological data (e.g., heart rate, respiration, skin conductance) that individuals wear, carry, or access during their normal daily activities. mHealth system designers have started to use the health information from physiological data to deliver behavior-change interventions. However, little research provides guidance about how one can design mHealth systems to use mobile biosensors for health behavior change. In order to address this research gap, we conducted an exploratory study. Following a hybrid approach that combines deductive and inductive reasoning, we integrated a body of fragmented literature and conducted 30 semi-structured interviews with mHealth stakeholders. From this study, we developed a theoretical framework and six general design guidelines that shed light on the theoretical pathways for how the mHealth interface can facilitate behavior change and provide practical design considerations

1.6 μm emission based on linear loss control in a Er:Yb doped double-clad fiber laser

Based on the control of the linear losses of the cavity, we demonstrate the possibility to achieve filterless laser emission above 1.6 μm, from a C-band double-clad Er:Yb doped fiber amplifier. The concept is validated in both continuous wave and mode-locked regimes, using a figure-of-eight geometry. A unidirectional ring cavity is also tested in the continuous regime. Spectral properties of laser emissions are characterized as a function of the intracavity linear losses

Oil quality and aroma composition of 'Chemlali' olive trees (Olea europaea L.) under three irrigation regimes

The present work focused on the chemical composition of monovarietal virgin olive oil from the cultivar Chemlali cultivated in the South of Tunisia: sub-arid zone under three different irrigation regimes: stressed, moderate and well irrigation treatment with the restitution of 50, 75 and 100% of crop evapotranspiration (ETc), respectively. Quality characteristics (acidity and peroxide value) and chemical data (antioxidant compound, fatty acids volatile compounds and oxidative stability) were studied in addition to the pomological characteristic of olive fruit. Results show that there were significant differences observed in oil composition according to the irrigation regime applied. Total phenols, bitterness intensity and LOX products content showed the highest values for low irrigation regime, whereas polyunsaturated fatty acid and oxidative susceptibility values had highest values for olive oil from well irrigated trees. Analytic characteristic of fruits showed the highest values of pulp/stone ratios from olive trees irrigated by the highest amount of wate

Minimally invasive versus conventional aortic valve replacement: a propensity-matched study from the UK National Data

Minimally invasive aortic valve replacement (MIAVR) has been demonstrated as a safe and effective option but remains underused. We aimed to evaluate outcomes of isolated MIAVR compared with conventional aortic valve replacement (CAVR).Data from The National Institute for Cardiovascular Outcomes Research (NICOR) were analyzed at seven volunteer centers (2006-2012). Primary outcomes were in-hospital mortality and midterm survival. Secondary outcomes were postoperative length of stay as well as cumulative bypass and cross-clamp times. Propensity modeling with matched cohort analysis was used.Of 307 consecutive MIAVR patients, 151 (49%) were performed during the last 2 years of study with a continued increase in numbers. The 307 MIAVR patients were matched on a 1:1 ratio. In the matched CAVR group, there was no statistically significant difference in in-hospital mortality [MIAVR, 4/307,(1.3%); 95% confidence interval (CI), 0.4%-3.4% vs CAVR, 6/307 (2.0%); 95% CI, 0.8%-4.3%; P = 0.752]. One-year survival rates in the MIAVR and CAVR groups were 94.4% and 94.6%, respectively. There was no statistically significant difference in midterm survival (P = 0.677; hazard ratio, 0.90; 95% CI, 0.56-1.46). Median postoperative length of stay was lower in the MIAVR patients by 1 day (P = 0.009). The mean cumulative bypass time (94.8 vs 91.3 minutes; P = 0.333) and cross-clamp time (74.6 vs 68.4 minutes; P = 0.006) were longer in the MIAVR group; however, this was significant only in the cross-clamp time comparison.Minimally invasive aortic valve replacement is a safe alternative to CAVR with respect to operative and 1-year mortality and is associated with a shorter postoperative stay. Further studies are required in high-risk (logistic EuroSCORE > 10) patients to define the role of MIAVR