Dynamics of magnetic modulation of ferrofluid droplets for digital microfluidic applications

Active control of droplet generation in a microfluidic platform attracts interest for development of digital microfluidic devices ranging from biosensors to micro-reactors to point-of-care diagnostic devices. The present paper characterizes, through an unsteady three-dimensional Volume of Fluid (VOF) simulation, the active control of ferrofluid droplet generation in a microfluidic T-junction in presence of a non-uniform magnetic field created by an external magnetic dipole. Two distinctly different positions of the dipole were considered – one upstream of the junction and one downstream. While keeping the ferrofluid flow rate fixed, a parametric variation of the continuous phase capillary number, dipole strength, and dipole position was carried out. Differences in the flow behaviour in terms of dripping or jetting and the droplet characteristics in terms of droplet formation time period and droplet size were studied. The existence of a threshold dipole strength, below which the magnetic force was not able to influence the flow behaviour, was identified. It was also observed that, for dipoles placed upstream of the junction, droplet formation was suppressed at some higher dipole strengths, and this value was found to increase with increasing capillary number. Droplet time period was also found to increase with increasing dipole strength, along with droplet size, i.e. an increase in droplet volume

THE BAND SPECTRUM OF GALLIUM OXIDE AND ISOTOPE EFFECT OF GALLIUM

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Autonomous transport and splitting of a droplet on an open surface

Pumpless transport of droplets on open surfaces has gained significant attention because of its applications starting from vapor condensation to Lab-on-a-Chip systems. Mixing two droplets on open surfaces can be carried out quickly by using wettability patterning. However, it is quite challenging to split a droplet in the absence of external stimuli because of the interfacial energy of the droplet. Here, we demonstrate a standalone power-free technique for transport and splitting of droplets on open surfaces using continuous wettability gradients. A droplet moves continuously from a low to a high wettability region on the wettability-gradient surface. A Y-shaped wettability-gradient track – laid on a superhydrophobic background – is used to investigate the dynamics of the splitting process. A three-dimensional phase-field Cahn-Hilliard model for interfaces and the Navier-Stokes equations for transport are employed and solved numerically using the finite element method. Numerical results are used to decipher the motion and splitting of droplet at the Y junction using the principle of energy conservation. It is observed that droplet splitting depends on the configuration of the Y junction; droplets split faster for the superhydrophobic wedge angle of 90∘ and the splitting ratio (ratio of the sizes of daughter droplets) depends on the widths of the Y branches. A critical branch-width ratio (w2w1=0.79) is identified below which the droplet does not split and moves towards the branch of higher width and settles there. The present study provides the required theoretical underpinnings to achieve autonomous transport and splitting of droplets on open surfaces, which has clear potential for applications in Lab-on-a-Chip devices

Investigations in the lnfra-Red: Part I

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Behavioral implications of shortlisting procedures

We consider two-stage “shortlisting procedures” in which the menu of alternatives is first pruned by some process or criterion and then a binary relation is maximized. Given a particular first-stage process, our main result supplies a necessary and sufficient condition for choice data to be consistent with a procedure in the designated class. This result applies to any class of procedures with a certain lattice structure, including the cases of “consideration filters,” “satisficing with salience effects,” and “rational shortlist methods.” The theory avoids background assumptions made for mathematical convenience; in this and other respects following Richter’s classical analysis of preference-maximizing choice in the absence of shortlisting

Investigations of machining characteristics in upgraded MQL assisted turning of pure titanium alloy using evolutionary algorithms

Environmental protection is the major concern of any form of manufacturing industry today. As focus has shifted towards sustainable cooling strategies, minimum quantity lubrication (MQL) has proven its usefulness. The current survey intends to make the MQL strategy more effective while improving its performance. A Ranque–Hilsch vortex tube (RHVT) was implemented into the MQL process in order to enhance the performance of the manufacturing process. The RHVT is a device that allows for separating the hot and cold air within the compressed air flows that come tangentially into the vortex chamber through the inlet nozzles. Turning tests with a unique combination of cooling technique were performed on titanium (Grade 2), where the effectiveness of the RHVT was evaluated. The surface quality measurements, forces values, and tool wear were carefully investigated. A combination of analysis of variance (ANOVA) and evolutionary techniques (particle swarm optimization (PSO), bacteria foraging optimization (BFO), and teaching learning-based optimization (TLBO)) was brought into use in order to analyze the influence of the process parameters. In the end, an appropriate correlation between PSO, BFO, and TLBO was investigated. It was shown that RHVT improved the results by nearly 15% for all of the responses, while the TLBO technique was found to be the best optimization technique, with an average time of 1.09 s and a success rate of 90%

Mechanisms of action of the sodium-glucose cotransporter-2 (SGLT2) inhibitor canagliflozin on tubular inflammation and damage: A post hoc mediation analysis of the CANVAS trial

Aims: To test the hypothesis that the reduction in urinary kidney injury molecule-1 (KIM-1) observed with the sodium-glucose cotransporter-2 (SGLT2) inhibitor canagliflozin is mediated through its effects on urine albumin to creatinine ratio (UACR) and monocyte chemoattractant protein-1 (MCP-1) by assessing the proportion of the effect of canagliflozin on KIM-1 that is mediated through its effects on MCP-1 and UACR in patients with type 2 diabetes and albuminuric kidney disease. Material and methods: We measured KIM-1 and MCP-1 levels in urine samples from the CANVAS trial at baseline and Week 52 with the Mesoscale QuickPlex SQ 120 platform. KIM-1 and MCP-1 were standardized by urinary creatinine (Cr). The proportion of the effect of canagliflozin that is mediated through UACR and MCP-1/Cr on KIM-1/Cr was estimated with G-computation. Results: In total, 763 patients with micro- or macroalbuminuria (17.6% of the total cohort) were included. Baseline characteristics were well balanced between the canagliflozin and placebo group. At Year 1, canagliflozin compared to placebo reduced UACR, MCP-1/Cr and KIM-1/Cr by 40.4% (95% CI 31.0, 48.4), 18.1% (95% CI 8.9, 26.4) and 30.9% (95% CI 23.0, 38.0), respectively. The proportion of the effect of canagliflozin on KIM-1/Cr mediated by its effect on UACR and in turn on MCP-1/Cr was 15.2% (95% CI 9.4, 24.5). Conclusion: Canagliflozin reduces urinary KIM-1, suggesting decreased tubular damage. This effect was partly mediated through a reduction in MCP-1, indicative of reduced tubular inflammation, which was in turn mediated by a reduction in UACR. This post hoc analysis suggests that urinary albumin leakage may lead to tubular inflammation and induction of injury, and provide mechanistic insight for how canagliflozin may ameliorate tubular damage, but further research is required to confirm these findings

A New Statistical Image Analysis Approach and Its Application to Hippocampal Morphometry

In this work, we propose a novel and powerful image analysis framework for hippocampal morphometry in early mild cognitive impairment (EMCI), an early prodromal stage of Alzheimer’s disease (AD). We create a hippocampal surface atlas with subfield information, model each hippocampus using the SPHARM technique, and register it to the atlas to extract surface deformation signals. We propose a new alternative to standard random field theory (RFT) and permutation image analysis methods, Statistical Parametric Mapping (SPM) Distribution Analysis or SPM-DA, to perform statistical shape analysis and compare its performance with that of RFT methods on both simulated and real hippocampal surface data. The major strengths of our framework are twofold: (a) SPM-DA provides potentially more powerful algorithms than standard RFT methods for detecting weak signals, and (b) the framework embraces the important hippocampal subfield information for improved biological interpretation. We demonstrate the effectiveness of our method via an application to an AD cohort, where an SPM-DA method detects meaningful hippocampal shape differences in EMCI that are undetected by standard RFT methods

Association between circulating GDF-15 and cardio-renal outcomes and effect of canagliflozin: results from the CANVAS trial

Background Studies have suggested that sodium glucose co-transporter 2 inhibitors exert anti-inflammatory effects. We examined the association of baseline growth differentiation factor-15 (GDF-15), a marker of inflammation and cellular injury, with cardiovascular events, hospitalization for heart failure (HF), and kidney outcomes in patients with type 2 diabetes in the CANVAS (Canagliflozin Cardiovascular Assessment Study) and determined the effect of the sodium glucose co-transporter 2 inhibitor canagliflozin on circulating GDF-15. Methods and Results The CANVAS trial randomized 4330 people with type 2 diabetes at high cardiovascular risk to canagliflozin or placebo. The association between baseline GDF-15 and cardiovascular (non-fatal myocardial infarction, non-fatal stroke, cardiovascular death), HF, and kidney (40% estimated glomerular filtration rate decline, end-stage kidney disease, renal death) outcomes was assessed using multivariable adjusted Cox regression models. During median follow-up of 6.1 years (N=3549 participants with available samples), 555 cardiovascular, 129 HF, and 137 kidney outcomes occurred. Each doubling in baseline GDF-15 was significantly associated with a higher risk of cardiovascular (hazard ratio [HR], 1.2; 95% CI, 1.0‒1.3), HF (HR, 1.5; 95% CI, 1.2‒2.0) and kidney (HR, 1.5; 95% CI, 1.2‒2.0) outcomes. Baseline GDF-15 did not modify canagliflozin's effect on cardiovascular, HF, and kidney outcomes. Canaglifozin treatment modestly lowered GDF-15 compared with placebo; however, GDF-15 did not mediate the protective effect of canagliflozin on cardiovascular, HF, or kidney outcomes. Conclusions In patients with type 2 diabetes at high cardiovascular risk, higher GDF-15 levels were associated with a higher risk of cardiovascular, HF, and kidney outcomes. Canagliflozin modestly lowered GDF-15, but GDF-15 reduction did not mediate the protective effect of canagliflozin

Interleukin-6 and Cardiovascular and Kidney Outcomes in Patients With Type 2 Diabetes: New Insights From CANVAS

OBJECTIVE The inflammatory cytokine interleukin-6 (IL-6) is associated with cardiovascular (CV) and kidney outcomes in various populations. However, data in patients with type 2 diabetes are limited. We assessed the association of IL-6 with CV and kidney outcomes in the Canagliflozin Cardiovascular Assessment Study (CANVAS) and determined the effect of canagliflozin on IL-6. RESEARCH DESIGN AND METHODS Patients with type 2 diabetes at high CV risk were randomly assigned to canagliflozin or placebo. Plasma IL-6 was measured at baseline and years 1, 3, and 6. The composite CV outcome was nonfatal myocardial infarction, nonfatal stroke, or CV death; the composite kidney outcome was sustained ≥40% estimated glomerular filtration rate decline, end-stage kidney disease, or kidney-related death. Multi-variable-adjusted Cox proportional hazards regression was used to estimate the associations between IL-6 and the outcomes. The effect of canagliflozin on IL-6 over time was assessed with a repeated-measures mixed-effects model. RESULTS The geometric mean IL-6 at baseline, available in 3,503 (80.2%) participants, was 1.7 pg/mL. Each doubling of baseline IL-6 was associated with 14% (95% CI 4, 24) and 21% (95% CI 1, 45) increased risk of CV and kidney outcomes, respectively. Over 6 years, IL-6 increased by 5.8% (95% CI 3.4, 8.3) in the placebo group. Canagliflozin modestly attenuated the IL-6 increase (absolute percentage difference vs. placebo 4.4% [95% CI 1.3, 9.9; P = 0.01]). At year 1, each 25% lower level of IL-6 compared with baseline was associated with 7% (95% CI 1, 22) and 14% (95% CI 5, 22) lower risks for the CV and kidney outcome, respectively. CONCLUSIONS In patients with type 2 diabetes at high CV risk, baseline IL-6 and its 1-year change were associated with CV and kidney outcomes. The effect of IL-6–lowering therapy on CV, kidney, and safety outcomes remains to be tested