Shaping and transporting diamagnetic sessile drops

Electromagnetic fields are commonly used to control small quantities of fluids in microfluidics and digital microfluidics. Magnetic control techniques are less well studied than their electric counterparts, with only a few investigations into liquid diamagnetism. The ratio of magnetic to surface energy (magnetic Bond number B m) is an order of magnitude smaller for diamagnetic drops (B m ≈-0.3 at 1.2 T applied field) than for paramagnetic drops (B m ≈ 9.0 at 1.2 T applied field). This weaker interaction between the magnetic field and the diamagnetic drop has led to the phenomenon being overlooked in digital microfluidics. Here, we investigate shaping and transport of diamagnetic drops using magnetostatic fields. Our findings highlight how diamagnetic fluids can be used as a novel tool in the toolbox of microfluidics and digital microfluidics

Field-induced shaping of sessile paramagnetic drops

We use the electromagnetic stress tensor to describe the elongation of paramagnetic drops in uniform magnetic fields. This approach implies a linear relationship between the shape of the drops and the square of the applied field, which we confirm experimentally. We show that this effect scales with the volume and susceptibility of the drops. By using this unified electromagnetic approach, we highlight the potential applications of combining electric and magnetic techniques for controlled shaping of drops in liquid displays, liquid lenses, and chemical mixing of drops in microfluidics

Shaping drops with magnetic fields

The control of small volumes of fluids (or drops) is important for a wide range of applications, including lab-on-chip devices, where drops are transported and merged for sensing and chemical mixing; liquid lenses, where drops are shaped to set optical properties; and printing, where drops are generated by nozzles. Electric techniques are widely used to generate, transport, split and merge drops. Equivalent magnetic techniques are less well-known. Similarly to electric dipoles in electric fields, magnetic dipoles experience a force in magnetic fields. This effect, called magnetophoresis, is used to shape ferrofluids in magnetic valves and seals. Interest in shaping drops with magnetic fields for microfluidics has recently increased, and ferrofluids and paramagnetic salt solutions have been studied. The rich phenomenology of the interaction of magnetic fields and fluids offers ample opportunities for exploration. Diamagnetic fluids for example have no natural electric equivalent and are rarely studied as a tool for microfluidics. In this thesis, I study the shaping of drops with magnetic fields. My research focus is on para- and diamagnetic salt solutions. Deformation of drops using external fields and induced magnetism has not been fully explored in the literature. I study here how induced magnetism can shape the liquid-vapour interface of drops and control solids that float on them. This thesis includes (i) an introduction to the background of the interaction of electromagnetic fields and fluids; (ii) a derivation of an expression for the shape of drops in electromagnetic fields; (iii) experimental validation of this expression through the measurement of the shape of para- and diamagnetic axisymmetric sessile drops in homogeneous magnetic fields; (iv) demonstration of the transport of para- and diamagnetic drops in magnetic field gradients; (v) explorations of the use of shaping drops with magnetic fields for rheological measurements, and for the controlled driving of objects floating on drops. In summary, I explore how drops can be shaped in homogeneous magnetic fields, and how the drops can be transported by magnetic field gradients. These fundamental investigations may help stimulate novel applications of the controlled shaping of drops with magnetic fields. In particular, I explore how this technique can be used in rheology for food or medical research

Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action

Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or “golden rules,” for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice

Changes in Family Physicians’ Perceptions of Electronic Cigarettes in Tobacco Use Counseling Between 2016 and 2019: Changes in Family Physicians’ Perceptions of Electronic Cigarettes

Introduction: Given the recent reports of e-cigarette, or vaping, product use-associated lung injury (EVALI) and harm of e-cigarettes, the authors evaluated changes in the perception of e-cigarettes as smoking cessation tools in 2019 relative to 2016. The authors also evaluated the sources family physicians most commonly use to receive information regarding e-cigarettes. Methods: Authors conducted a cross-sectional online survey of 248 community family physicians in Kansas from October to December 2019. The authors used a 11-item questionnaire to measure the participants’ perceptions of recommending e-cigarettes to patients for tobacco cessation. The authors used a mixed method approach to collect, analyze, and interpret the data. Standard descriptive statistics, Likelihood-Ratio/Fisher’s exact tests, and immersion-crystallization approached were used to analyze the data. Results: The response rate was 59.3% (147/248). Proportion of the family physicians who did not recommend e-cigarettes for smoking cessation was significantly higher in 2019 than in 2016 (86% vs 82%; χ2 [1, n = 261] = 12.31; P < .01). Several reasons regarding respondents’ perception of e-cigarettes as smoking cessation tools were reported. The medical literature and news media were the top sources where family physicians accessed e-cigarettes information. Conclusion: Our study has suggested that the majority of family physicians in our data do not currently recommend e-cigarettes for tobacco cessation. Opinions regarding the efficacy and safety of e-cigarettes are influenced by information source. Future, larger studies would be beneficial to further determine physicians’ beliefs and practices regarding e-cigarettes as smoking cessation products

High Levels of IL-10 and CD4+CD25hi+ Treg Cells in Endemic Burkitt’s Lymphoma Patients

Background: The interplay between Epstein-Barr virus infection, malaria, and endemic Burkitt’s Lymphoma is not well understood. Reports show diminished EBV-specific Th1 responses in children living in malaria endemic areas and deficiency of EBNA1-specific IFN-γ T cell responses in children with endemic Burkitt’s Lymphoma (eBL). This study, therefore, examined some factors involved in the loss of EBNA-1-specific T cell responses in eBL. Methods: T-cell subset frequencies, activation, and IFN-γ- or IL-4-specific responses were analyzed by flow-cytometry. Plasma cytokine levels were measured by ELISA. Results: CD4+ and CD8+ cells in age- and sex-matched healthy controls (n = 3) expressed more IFN-γ in response to all immunostimulants than in pediatric endemic BL (eBL) patients (n = 4). In healthy controls, IFN-γ expression was higher than IL-4 expression, whereas in eBL patients the expression of IL-4 by CD4+ cells to EBNA-1 was slightly higher than IFN-γ. Moreover, the blood levels of TNF-α was significantly lower (p = 0.004) while IL-10 was significantly higher (p = 0.038), in eBL patients (n = 21) compared to controls (n = 16). Additionally, the frequency of CD4+CD25hi+ T cells was higher in both age-matched acute uncomplicated malaria (n = 26) and eBL (n = 14) patients compared to healthy controls (n = 19; p = 0.000 and p = 0.027, respectively). Conclusion: The data suggest that reduced Th1 response in eBL might be due to increased levels of IL-10 and T reg cells