Fluorescence of Supported Phospholipid Bilayers Recorded in a Conventional Horizontal-Beam Spectrofluorometer

Supported phospholipid bilayers are a convenient model of cellular membranes in studies of membrane biophysics and protein-lipid interactions. Traditionally, supported lipid bilayers are formed on a flat surface of a glass slide to be observed through fluorescence microscopes. This paper describes a method to enable fluorescence detection from the supported lipid bilayers using standard horizontal-beam spectrofluorometers instead of the microscopes. In the proposed approach, the supported lipid bilayers are formed on the inner optical surfaces of the standard fluorescence microcell. To enable observation of the bilayer absorbed on the cell wall, the microcell is placed in a standard fluorometer cell holder and specifically oriented to expose the inner cell walls to both excitation and emission channels with a help of the custom cell adaptor. The signal intensity from supported bilayers doped with 1 % (mol) of rhodamine-labeled lipid in the standard 3-mm optical microcell was equivalent to fluorescence of the 70–80 nM reference solution of rhodamine recorded in a commercial microcell adaptor. Because no modifications to the instruments are required in this method, a variety of steady-state and time-domain fluorescence measurements of the supported phospholipid bilayers may be performed with the spectral resolution using standard horizontal-beam spectrofluorometers

A software approach to defeating side channels in last-level caches

We present a software approach to mitigate access-driven side-channel attacks that leverage last-level caches (LLCs) shared across cores to leak information between security domains (e.g., tenants in a cloud). Our approach dynamically manages physical memory pages shared between security domains to disable sharing of LLC lines, thus preventing "Flush-Reload" side channels via LLCs. It also manages cacheability of memory pages to thwart cross-tenant "Prime-Probe" attacks in LLCs. We have implemented our approach as a memory management subsystem called CacheBar within the Linux kernel to intervene on such side channels across container boundaries, as containers are a common method for enforcing tenant isolation in Platform-as-a-Service (PaaS) clouds. Through formal verification, principled analysis, and empirical evaluation, we show that CacheBar achieves strong security with small performance overheads for PaaS workloads

Effects of Dose Timing on Fluid Excretion During Sodium-Aided Hyperhydration Protocols

Co-consumption of sodium and water has been shown to be superior in promoting hyperhydration compared to consumption of an equal amount of water alone. Most sodium-aided hyperhydration studies have provided subjects with a bolus of fluid followed by a urine collection period. However the effect of providing equal amounts of fluid in a single vs. multiple doses over time on fluid retention has not been systematically studied. PURPOSE: To compare the effects of different dosing strategies on urine excretion levels following the consumption of consistent amounts of sodium and water. METHODS: Urine excretion was measured during five separate 2-hr hyperhydration protocols in 13 well hydrated male subjects (23 ± 3 yr, 176.1 ± 10.1 cm, 82.2 ± 19.4 kg) who were free from known renal, digestive, and cardiovascular disease. Each protocol began with a complete bladder void and assessment of urine specific gravity (USG). Subjects then consumed 20 mL H2O ∙ kg bm-1 and 110 mg NaCl ∙ kg bm-1 in five different dosing strategies: the entire dose was consumed at the beginning of the period (1X), ½ of the dose was consumed at the beginning and ½ consumed after 60 min (2X), and 1/3 of the dose was consumed at the beginning and 1/3 was consumed after 45 and 90 min (3X), ¼ of the dose was consumed at the beginning and after 30, 60, and 90 min (4X), and 1/7 of the dose was consumed at the beginning and after 15, 30, 45, 60, 75, 90 min (7X). Protocols were administered in a randomized, crossover fashion. Total urine excretions (TUE) during the 2 hr collection periods were expressed as a percent of the H2O consumed. USG and TUE were compared using repeated-measures ANOVA and Sidak post hoc analyses. RESULTS: USGs were 1.006 ± 0.004 (1X), 1.007 ± 0.003 (2X), 1.009 ± 0.005 (3X). 1.007 ± 0.004 (4X), and 1.007 ± 0.005 (7X) (P = 0.37 – 1.00) indicating that subjects were well and similarly hydrated for each trial. TUE expressed as a percentage of H2O consumed were 75 ± 18% (1X), 69 ± 11% (2X), 52% ± 15% (3X), 59 ± 15% (4X), and 60 ± 16% (7X). Significant differences in TUE were seen between 1X and 3X (P = 0.03) and 2X and 3X (P = 0.006). No significant difference in TUE was detected between any of the other protocols (P = 0.16 – 1.00). CONCLUSION: The data suggest that hyperhydration is better achieved when water and sodium are consumed in three equal doses over 90 min when compared to consuming an equal amount of a sodium and water dose in a single bolus or in two equal doses over a 60 min period. Consuming water in four or seven equal doses over 90 min did not result in better fluid retention than consuming an equal amount of water in a single bolus or in two equal doses over a 60 min period

Effects of Fluid Consumption Volumes on Fluid Retention during Sodium-Aided Hyperhydration Protocols

Numerous investigations have supported the use of sodium-aided hyperhydration to improve hydration status and exercise performance in the heat. Sodium-aided hyperhydration studies typically utilize fluid volumes ranging from 10 - 25 mL ∙ kg bm-1; however, optimum fluid consumption volumes have not been identified. While it may seem logical that larger fluid consumption volumes would promote greater hyperhydration, excessive expansion of plasma volume could stimulate high-pressure baroreceptors and promote excessive diuresis. PURPOSE: To compare the effects of different fluid consumption volumes on fluid retention during a sodium-aided hyperhydration protocol. METHODS: Urine excretion was measured during four separate sodium-aided hyperhydration protocols in thirteen male subjects (24 ± 4 yrs, 75.2 ± 9.5 kg, 177.0 ± 8.9 cm) who were free from known renal, digestive, and cardiovascular disease. Each protocol began with a complete bladder void and assessment of urine specific gravity (USG). Subjects then consumed one of four different isotonic volumes of sodium and water in three equal doses separated by 45 min. Total water consumptions for the four protocols were 20 mL ∙ kg bm-1 (20), 15 mL ∙ kg bm-1 (15), 10 mL ∙ kg bm-1 (10), and 5 mL ∙ kg bm-1 (5). Subjects remained in the lab for two hours following the consumption of the initial fluid-sodium dose and performed a measure bladder void every 20 min. USGs and total fluid retentions (total fluid consumed – total urine excreted) for each protocol were compared using separate, one-way, repeated measures ANOVA and Sidak post-hoc analyses. RESULTS: USGs for the four protocols were 1.009 ± 0.005 (20), 1.010 ± (0.002), 1.016 ± 0.028 (10), and 1.009 ± 0.005 (5) (P \u3e 0.90), indicating that all subjects were well and similarly hydrated for each protocol. Fluid retentions for the four protocols were 10.8 ± 2.7 mL ∙ kg bm-1 (20), 7.5 ± 2.3 mL ∙ kg bm-1 (15), 5.6 ± 2.5 mL ∙ kg bm-1 (10), and 2.6 ± 1.4 mL ∙ kg bm-1 (5) (P ≤ 0.04). CONCLUSION: Subjects retained approximately 50% of the fluid that they consumed regardless of their fluid consumption volumes. These results suggest that, when consuming 5 – 20 mL ∙ kg bm-1 of fluid during sodium-aided hyperhydration protocols, fluid retention levels increase linearly with an increase in fluid consumption volumes and, to attain the highest level of hyperhydration, at least 20 mL ∙ kg bm-1 of fluid should be consumed

On the accelerated settling of fine particles in a bidisperse slurry

An estimation of increasing the volume average sedimentation velocity of fine particles in bidisperse suspension due to their capturing in the circulation zone formed in the laminar flow of incompressible viscous fluid around the spherical coarse particle is proposed. The estimation is important for an explanation of the nonmonotonic shape of the separation curve observed for hydrocyclones. The volume average sedimentation velocity is evaluated on the basis of a cellular model. The characteristic dimensions of the circulation zone are obtained on the basis of a numerical solution of Navier-Stokes equations. Furthermore, these calculations are used for modelling the fast sedimentation of fine particles during their cosedimentation in bidisperse suspension. It was found that the acceleration of sedimentation of fine particles is determined by the concentration of coarse particles in bidisperse suspension, and the sedimentation velocity of fine fraction is proportional to the square of the coarse and fine particle diameter ratio. The limitations of the proposed model are ascertained

Relaxation Dynamics in See-Saw Shaped Dy(III) Single-Molecule Magnets

Utilizing a terphenyl bisanilide ligand, two Dy(III) compounds [K(DME)n][LArDy(X)2] (LAr = {C6H4[(2,6-iPrC6H3)NC6H4]2}2−), X = Cl (1) and X = I (2) were synthesized. The ligand imposes an unusual see-saw shaped molecular geometry leading to a coordinatively unsaturated metal complex with near-linear N–Dy–N (avg. 159.9° for 1 and avg. 160.4° for 2) angles. These compounds exhibit single-molecule magnet (SMM) behavior with significant uniaxial magnetic anisotropy as a result of the transverse coordination of the bisanilide ligand which yields high energy barriers to magnetic spin reversal of Ueff = 1334 K/927 cm−1 (1) and 1278 K/888 cm−1 (2) in zero field. Ab initio calculations reveal that the dominant crystal field of the bisanilide ligand controls the orientation of the main magnetic axis which runs nearly parallel to the N–Dy–N bonds, despite the identity of the halide ligand. Analysis of the relaxation dynamics reveals a ca. 14-fold decrease in the rate of quantum tunneling of the magnetisation when X = I (2). Most notably, the relaxation times were on average 5.6× longer at zero field when the heavier group 17 congener was employed. However, no direct evidence of a heavy atom effect on the Orbach relaxation was obtained as the height of the barrier is defined by the dominant bisanilide ligand.<br/

Mycophenolate mofetil inhibits the development of Coxsackie B3-virus-induced myocarditis in mice

BACKGROUND: Viral replication as well as an immunopathological component are assumed to be involved in the development of coxsackie B virus (CBV)-induced myocarditis. We observed that mycophenolic acid (MPA), the active metabolite of the immunosuppressive agent mycophenolate mofetil (MMF), inhibits coxsackie B3 virus (CBV3) replication in primary Human myocardial fibroblasts. We therefore studied whether MMF, which is thus endowed with a direct antiviral as well as immunosuppressive effect, may prevent CBV-induced myocarditis in a murine model. RESULTS: Four week old C3H-mice were infected with CBV3 and received twice daily, for 7 consecutive days (from one day before to 5 days post-virus inoculation) treatment with MMF via oral gavage. Treatment with MMF resulted in a significant reduction in the development of CBV-induced myocarditis as assessed by morphometric analysis, i.e. 78% reduction when MMF was administered at 300 mg/kg/day (p < 0.001), 65% reduction at 200 mg/kg/day (p < 0.001), and 52% reduction at 100 mg/kg/day (p = 0.001). The beneficial effect could not be ascribed to inhibition of viral replication since titers of infectious virus and viral RNA in heart tissue were increased in MMF-treated animals as compared to untreated animals. CONCLUSION: The immunosuppressive agent MMF results in an important reduction of CBV3-induced myocarditis in a murine model