Simulations of a lattice model of two-headed linear amphiphiles: influence of amphiphile asymmetry

Using a 2D lattice model, we conduct Monte Carlo simulations of micellar aggregation of linear-chain amphiphiles having two solvophilic head groups. In the context of this simple model, we quantify how the amphiphile architecture influences the critical micelle concentration (CMC), with a particular focus on the role of the asymmetry of the amphiphile structure. Accordingly, we study all possible arrangements of the head groups along amphiphile chains of fixed length $N=12$ and 16 molecular units. This set of idealized amphiphile architectures approximates many cases of symmetric and asymmetric gemini surfactants, double-headed surfactants and boloform surfactants. Consistent with earlier results, we find that the number of spacer units $s$ separating the heads has a significant influence on the CMC, with the CMC increasing with $s$ for $s<N/2$. In comparison, the influence of the asymmetry of the chain architecture on the CMC is much weaker, as is also found experimentally.Comment: 30 pages, 17 fgure

Simulations of a lattice model of two-headed linear amphiphiles: influence of amphiphile asymmetry

Using a 2D lattice model, we conduct Monte Carlo simulations of micellar aggregation of linear-chain amphiphiles having two solvophilic head groups. In the context of this simple model, we quantify how the amphiphile architecture influences the critical micelle concentration (CMC), with a particular focus on the role of the asymmetry of the amphiphile structure. Accordingly, we study all possible arrangements of the head groups along amphiphile chains of fixed length $N=12$ and 16 molecular units. This set of idealized amphiphile architectures approximates many cases of symmetric and asymmetric gemini surfactants, double-headed surfactants and boloform surfactants. Consistent with earlier results, we find that the number of spacer units $s$ separating the heads has a significant influence on the CMC, with the CMC increasing with $s$ for $s<N/2$. In comparison, the influence of the asymmetry of the chain architecture on the CMC is much weaker, as is also found experimentally.Comment: 30 pages, 17 fgure

Systematic review of the natural history of untreated Hepatitis B

Review of longitudinal studies that evaluate relevant outcomes (eAg seroconversion, cirrhosis, hepato-cellular carcinoma, mortality) for untreated, chronic hepatitis

Shear deformable super-convergent finite element for steel beams strengthened with glass-fiber reinforced polymer (GFRP) plate

The present study investigates the flexural behaviour of steel beams strengthened by adhesively bonding a GFRP plate to one of the flanges. The model captures shear deformation effects and partial interaction between the steel and GFRP owing to the relative flexibility of the adhesive. A general closed form solution is first developed for the governing coupled system of differential equations. The solution is then used to formulate exact shape functions and develop a finite element with superior convergence characteristics. The model is used to investigate the response of multi-span continuous beams, determine the strength gained by GFRP strengthening, and quantify shear deformation effects on the response of strengthened beams. A technique capturing partial interaction effects is devised to characterize the flexural strength of Class 3 strengthened beams. A classification limit for strengthened Class 3 sections is also proposed within the framework of the Canadian Standard CAN-CSA S16 (2014).The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Antimicrobial Resistance and Human Mobility.

Antimicrobial resistance (AMR) is of increasing global concern. Human mobility is one factor that has recently been associated with AMR, though the extent of its impact has not yet been well established due to the limited availability of rigorous data. This review examines the existing literature regarding various types of human mobility including short-term travelers, forcibly displaced persons, migrant populations, and their association with global rates of AMR

Dermatologic conditions of adult refugees following resettlement in the United States, 2015 to 2018

Background: There is a paucity of literature regarding dermatologic conditions in migrant and refugee populations. Methods: We conducted a cross-sectional study of all adult refugees resettling in a region of Connecticut, U.S. from 7 January 2015 to 20 November 2018. We conducted a manual chart review to determine dermatologic conditions diagnosed during and within one year of resettlement. We used multivariable logistic regression to determine demographic and clinical factors associated with having any dermatologic condition. Results: We included 545 refugees primarily from Afghanistan (40.6%), Syria (24.6%) and Iraq (10.5%), with a median (interquartile range) age of 33 (28–40) years. Of the 545 participants, 213 (39.1%) had dermatologic conditions. Fifty-four participants (25%) had more than one dermatologic condition and 114 (53.5%) were diagnosed within the first month of resettlement. The most common categories of conditions were cutaneous infections (24.9%), inflammatory conditions (11.1%), and scar or burn (10.7%). Tobacco use was associated with having a cutaneous infection (OR 2.37, 95%CI:1.09–4.95), and younger age was associated with having a scar or burn (for each year increase in age, OR 0.95, 95%CI:0.91–0.99). Conclusion: Dermatologic conditions are common among adult refugees. The majority of conditions were diagnosed in the first month following resettlement suggesting that a high number of dermatologic conditions arise or go undetected and untreated during the migration process

Viral Hepatitis E Outbreaks in Refugees and Internally Displaced Populations, sub-Saharan Africa, 2010-2020.

Hepatitis E virus is a common cause of acute viral hepatitis. We analyzed reports of hepatitis E outbreaks among forcibly displaced populations in sub-Saharan Africa during 2010-2020. Twelve independent outbreaks occurred, and &gt;30,000 cases were reported. Transmission was attributed to poor sanitation and overcrowding

Risks and benefits of oral HIV pre-exposure prophylaxis for people with chronic hepatitis B

International audienceIndividuals with chronic hepatitis B virus (HBV) infection who are at substantial risk of HIV acquisition benefit from pre-exposure prophylaxis (PrEP) with tenofovir-based antiviral therapy. Considering that tenofovir potently inhibits HBV, providing PrEP to individuals with HBV effectively results in treatment of their HBV infection. However, some clinicians might be hesitant to initiate PrEP in people with chronic HBV due to unknown risks of HBV reactivation, hepatitis, and acute liver failure during periods of antiviral cessation. Unfortunately, these knowledge gaps affect scale up of PrEP among people with chronic HBV. Emerging data regarding the risks and benefits of antiviral cessation in people with chronic HBV suggest that PrEP can be safely initiated despite the risks of non-adherence or discontinuation. People with chronic HBV who stop PrEP should be closely monitored for HBV reactivation and hepatitis flares after antiviral cessation

P A Coffie MD PhD); Programme PAC-CI, Abidjan, Côte d'Ivoire (P A Coffie, M G Kouamé MD PhD); stichting hiv monitoring, Amsterdam, Netherlands (

International audienceIndividuals with chronic hepatitis B virus (HBV) infection who are at substantial risk of HIV acquisition benefit from pre-exposure prophylaxis (PrEP) with tenofovir-based antiviral therapy. Considering that tenofovir potently inhibits HBV, providing PrEP to individuals with HBV effectively results in treatment of their HBV infection. However, some clinicians might be hesitant to initiate PrEP in people with chronic HBV due to unknown risks of HBV reactivation, hepatitis, and acute liver failure during periods of antiviral cessation. Unfortunately, these knowledge gaps affect scale up of PrEP among people with chronic HBV. Emerging data regarding the risks and benefits of antiviral cessation in people with chronic HBV suggest that PrEP can be safely initiated despite the risks of non-adherence or discontinuation. People with chronic HBV who stop PrEP should be closely monitored for HBV reactivation and hepatitis flares after antiviral cessation