High-performance Flow Research Articles

An experimental data-driven mass-spring model of flexible Calliphora wings

Insect wings can undergo significant deformation during flapping motion owing to inertial, elastic and aerodynamic forces. Changes in shape then alter aerodynamic forces, resulting in a fully coupled fluid–structure interaction (FSI) problem. Here, we present detailed three-dimensional FSI simulations of deformable blowfly (Calliphora vomitoria) wings in flapping flight. A wing model is proposed using a multi-parameter mass-spring approach, chosen for its implementation simplicity and computational efficiency. We train the model to reproduce static elasticity measurements by optimizing its parameters using a genetic algorithm with covariance matrix adaptation (CMA-ES). Wing models trained with experimental data are then coupled to a high-performance flow solver run on massively parallel supercomputers. Different features of the modeling approach and the intra-species variability of elastic properties are discussed. We found that individuals with different wing stiffness exhibit similar aerodynamic properties characterized by dimensionless forces and power at the same Reynolds number. We further study the influence of wing flexibility by comparing between the flexible wings and their rigid counterparts. Under equal prescribed kinematic conditions for rigid and flexible wings, wing flexibility improves lift-to-drag ratio as well as lift-to-power ratio and reduces peak force observed during wing rotation.

High performance and long cycle life neutral zinc-iron flow batteries enabled by zinc-bromide complexation

Zinc-based flow batteries have attracted tremendous attention owing to their outstanding advantages of high theoretical gravimetric capacity, low electrochemical potential, rich abundance, and low cost of metallic zinc. Among which, zinc-iron (Zn/Fe) flow batteries show great promise for grid-scale energy storage. However, they still face challenges associated with the corrosive and environmental pollution of acid and alkaline electrolytes, hydrolysis reactions of iron species, poor reversibility and stability of Zn/Zn2+ redox couple. In this work, bromide ions are used to stabilize zinc ions via complexation interactions in the cost-effective and eco-friendly neutral electrolyte. Cyclic voltammetry results reveal that the redox reversibility between Zn and stabilized Zn2+ is greatly improved. The results of spectrum characterizations and density functional theory calculations verify that the formation of Zn[Brn(H2O)6-n]2-n (1 ≤ n ≤4, n is integer.) ions accounts for the increased electrochemical reversibility of Zn/Zn2+pair. Moreover, to overcome the bottleneck of slow kinetics of the coordination interactions between Zn2+ and Br−, ZnBr2 is judiciously selected as the electrolyte additive to promote the complexation process. Adopting K3Fe(CN)6 as the positive redox species to pair with the zinc anode with ZnBr2 modified electrolyte, the proposed neutral Zn/Fe flow batteries deliver excellent efficiencies and superior cycling stability over 2000 cycles (356 h), shedding light on their great potential for large scale energy storage.

Circulating endothelial progenitor cells as predictors of long-term cardiovascular mortality after myocardial infarction: which definition should we use?

Abstract Background Endothelial progenitor cells (EPCs) are bone marrow-derived cells that play a crucial role in vascular repair after an acute myocardial infarction (AMI). Recent studies suggest that circulating EPCs levels may be useful as a surrogate biomarker for cardiovascular (CV) events. Nevertheless, the lack of a consensual definition and phenotypic characterization of EPCs hampers its use in clinical practice. CD34+KDR+, CD45dimCD34+KDR+ and CD34+CD133+KDR+ are among the most used antigenic phenotypes to define circulating EPCs but the best phenotype to predict CV outcomes remains to be determined. Purpose To determine the EPCs' surface phenotype that best predicts long-term CV death after an AMI, and to evaluate its optimal cut-off point. Methods One-hundred AMI patients were prospectively enrolled in the study. Circulating EPCs were quantified through high-performance flow cytometer within the first 24 hours of admission using different surface markers combinations allowing to simultaneously compare three EPCs definitions: 1) CD34+KDR+, 2) CD45dimCD34+KDR+, 3) CD34+CD133+KDR+. Mean follow-up time was 8.0±2.2 years. Results The mean age of our population was 59.7±11.0, the majority of patients were male (90%), 65% had ST-elevation myocardial infarction (STEMI) and 35% non-ST segment elevation myocardial infarction (NSTEMI). Diabetes mellitus was present in 38% and hypertension in 67% of the studied sample. During the long-term follow-up, 34 patients had re-admissions due to cardiovascular causes, 11 of them for AMI. Thirty-one patients had major adverse cardiovascular events (MACE) and 19 died. Using ROC curves, the CD34+KDR+ phenotype showed the biggest area under the curve regarding prediction of CV mortality (0.722; p=0.010; confidence interval 95% (CI95%): 0.554 to 0.890). Patients with lower levels of EPCs according to this definition (≤0.022%) are 7 times more likely to die from CV causes at any time (hazard ratio = 7.55; p=0.008; CI95% 1.69 to 33.83). Conclusion The CD34+KDR+ phenotype appears to be the best definition of circulating EPCs for predicting long-term CV mortality after AMI. Further studies with larger samples are needed to clarify the optimal cut-off point for determining patients at risk and its role in everyday Cardiology. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Bolsa de Estudo João Porto da Sociedade Portuguesa de Cardiologia CD34+KDR+ as a predictor of CV death

Antioxidant Properties of Pecan Shell Bioactive Components of Different Cultivars and Extraction Methods.

Pecan shells are a rich source of various bioactive compounds with potential antioxidant and antimicrobial properties. This study investigated the effect of pecan variety and method extraction on the antioxidant property of shell extracts. Twenty different varieties of pecan shells were subjected to either aqueous or ethanolic extraction and were examined for total phenolics and antiradical activity. The phenolic content and antiradical activity of shell extracts were significantly (p < 0.05) varied with different pecan cultivars. The total phenolic content of ethanol extracts ranged from 304.2 (Caddo) to 153.54 (Cherokee) mg GAE g−1 of dry extract and was significantly greater (p < 0.05) than those obtained by aqueous extraction. The antiradical activity of ethanol extracts ranged from 840.6 (Maramec) to 526.74 (Caper Fear) mg TE g−1, while aqueous extracts ranged from 934.9 (Curtis) to 468.3 (Elliot) mg TE g−1. Chemical profiling of the crude and acid hydrolyzed extracts was performed by reverse phase high performance liquid chromatography and flow injection electrospray ionization mass spectrometry. Lignin degradation products such as lignols, dilignols, trilignols, and oligolignols were found to be the major components of tested extracts. Phenolic content and antiradical activity of pecan shell extracts are significantly varied with cultivars and methods of extraction.

Advances in the design and fabrication of high-performance flow battery electrodes for renewable energy storage

• The status of electrospun carbon fiber electrodes in flow batteries is reviewed. • The correlation between electrode properties and battery performance is discussed. • Challenges for maximized specific surface area & permeability are highlighted. • Perspectives for high-performance electrodes are presented. The redox flow battery is one of the most promising grid-scale energy storage technologies that has the potential to enable the widespread adoption of renewable energies such as wind and solar. To do so, the performance of redox flow batteries must be enhanced while the cost needs to be reduced. Electrodes are a key component where coupled electrochemical reactions and mass transport take place, and they play a critical role in determining the battery performance and system cost. This review summarizes recent developments in the design and fabrication of electrospun carbon fibers, which offers a bottom-up solution to the formation of electrodes with desired properties for high-performance flow batteries. The principles of electrospinning nanofibers and the key parameters that affect the morphologies of electrospun carbon fibers are discussed and summarized. The factors that influence electrode properties, including geometric structures, surface properties, electrical conductivity, mechanical strength, and wettability on the battery performances, are comprehensively elaborated with an emphasis on the electrode structure and surface properties that determine the mass transport and reaction kinetics. Finally, the scientific challenges and prospects of electrospun carbon fiber electrodes with maximized specific surface areas and hydraulic permeability are presented. This review offers insights into the design and development of advanced electrodes for next-generation flow batteries in the application of renewable energy storage.

Purification of membrane vesicles from Gram-positive bacteria using flow cytometry, after iodixanol density-gradient ultracentrifugation

Membrane vesicles (MVs) play biologically important roles in Gram-positive bacteria, and purification is essential for their study. Although high-performance flow cytometry has the capability to quantify and isolate specific small particles, it has not been examined for MV isolation. In this study, we used high-performance flow cytometry to analyze MV from Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis, prepared by iodixanol density-gradient ultracentrifugation. Analysis of the quality of MV samples before and after sorting showed that the flow cytometric sorting provided higher purity and uniformity compared to gradient isolation alone. The MV purification method using flow cytometry should prove useful for applications requiring a very high purity of MV samples such as proteomic, metagenomic or lipidomic studies.

Power Management Strategy Based on Virtual Inertia for DC Microgrids

This article presents a power management strategy (PMS) to control the power flow in a dc microgrid operating in the grid-connected mode. The microgrid model is composed of the ac utility grid interfaced with a voltage source inverter operating as a grid-forming converter (VSC), an energy storage system (ESS) formed by a battery bank and a bidirectional dc-dc converter operating as a grid-supporting unit, a distributed generation acting as a grid-feeding unit, and the customer loads with strict voltage regulation. The power management technique applies a virtual inertia concept together with a state of charge-based management function to regulate the charging and discharging process of the battery bank according to the dc microgrid power flow. Thus, high-rate peaks of power are avoided, which improves the ESS life cycle. With the proposed PMS, an autonomous power flow is achieved inside the dc microgrid, while the ac utility grid focuses exclusively upon forming the dc bus and processing the surplus or shortage of power. In addition, the proposed strategy simplifies the communication link between the grid inverter and the ESS, since the VSC power is the sole information exchanged. The experimental results show that the proposed PMS is reliable, leading to high ESS performance and power flow control within the dc microgrid, without degrading the dc bus voltage.

High performance flow through microbial fuel cells with anion exchange membrane

Microbial fuel cells (MFCs) can be limited to low power densities due to impacts of localized pH on electrode performance. Acidification of the anodic biofilm limits current generation by bacteria and the increase in cathode pH due to the oxygen reduction reaction reduces the whole cell potential. In this study, an anion exchange membrane (AEM) was used to make a membrane electrode assembly (MEA) in an MFC, with the anode, AEM, and cathode close together to enhance hydroxide ions transport from cathode to anode to minimize pH imbalances and reduce electrode spacing. With a flow-through felt anode the MFC produced 5.7 ± 0.4 W m−2 (at 29 ± 1 A m−2, internal resistance of 7.2 ± 0.6 mΩ m2, based on cross sectional area), which is one of the highest power densities produced in an MFC using a 50 mM phosphate buffer (PBS). Reducing the flowrate of the anolyte or air past the cathode decreased performance. Increasing the buffer concentration to 100 mM produced a maximum power density of 7.1 ± 0.4 W m−2, the highest power density ever recorded for an MFC, demonstrating the importance of buffer concentration in maintaining favorable localized pHs.

3D printing in analytical chemistry: current state and future

Abstract The rapid development of additive technologies in recent years is accompanied by their intensive introduction into various fields of science and related technologies, including analytical chemistry. The use of 3D printing in analytical instrumentation, in particular, for making prototypes of new equipment and manufacturing parts having complex internal spatial configuration, has been proved as exceptionally effective. Additional opportunities for the widespread introduction of 3D printing technologies are associated with the development of new optically transparent, current- and thermo-conductive materials, various composite materials with desired properties, as well as possibilities for printing with the simultaneous combination of several materials in one product. This review will focus on the application of 3D printing for production of new advanced analytical devices, such as compact chromatographic columns for high performance liquid chromatography, flow reactors and flow cells for detectors, devices for passive concentration of toxic compounds and various integrated devices that allow significant improvements in chemical analysis. A special attention is paid to the complexity and functionality of 3D-printed devices.

High-performance flow classification using hybrid clusters in software defined mobile edge computing

Mobile Edge Computing (MEC) provides different storage and computing capabilities within the access range of mobile devices. This moderates the burden of offloading compute/storage-intensive processes of the mobile devices to the centralized cloud data centers. As a result, the network latency is reduced and the quality of service provided for the mobile end users is improved. Different applications benefit from the large-scale deployments of MEC servers. However, the considerable complexity of managing large scale deployments of the sheer number of applications for the millions of mobile devices is a challenge. Recently, Software Defined Networking (SDN) is leveraged to resolve the problem by providing unified and programmable interfaces for managing network devices. Most of the current SDN packet processing services are tightly dependent on the packet classification service. This primary service classifies any incoming packet based on matching a set of specific fields of its header against a flow table. Acceleration of this basic process considerably increases the performance of the SDN-based MEC. In this paper, the hierarchical tree algorithm, which is a packet classification method, is parallelized using popular platforms on a cluster of Graphics Processing Units (GPUs), a cluster of Central Processing Units (CPUs), and a hybrid cluster. The best scenario for the parallel implementation of this algorithm on the CPU cluster is that which combines OpenMP and MPI.In this case, the throughput of the classifier is 4.2 million packets per second (MPPS). On the GPU cluster, two different scenarios have been used. In the first scenario, the global memory is used to store the rules and the Hierarchical-trie of the classifier while in the second scenario we break the filter set in a way that the resulting Hierarchical-trie of each subset could be stored in the shared memory of GPU. According to the results, although the first GPU cluster scenario achieves a throughput of 29.19 MPPS and a speedup 58 times as great as the serial mode, the second scenario is 12 times faster due to using the shared memory. The best performance, however, belongs to the hybrid cluster mode. The hybrid cluster achieves a throughput of 30.59 which is 1.4 MPPS more than the GPU cluster.

(20S)-Protopanaxadiol Ginsenosides Induced Cytotoxicity via Blockade of Autophagic Flux in HGC-27 Cells.

(20S)-Protopanaxadiol ginsenosides Rg3, Rh2 and PPD have been demonstrated for their anticancer activity. However, the underlying mechanism of their antitumor activity remains unclear. In the present study, we investigated the role of these three ginsenosides on cell proliferation and death of human gastric cancer cells (HGC-27 cells). The sulforhodamine B (SRB) assay, Western blot analysis, fluorescence microscopy, confocal microscopy, high performance liquid chromatography (HPLC) analysis, flow cytometry, and transmission electron microscopy (TEM) were used to evaluate cell proliferation, apoptosis, and autophagy. The results showed that both Rh2 and PPD were more effective than Rg3 in inhibiting HGC-27 cell proliferation and inducing cytoplasmic vacuolation, while no significant changes in apoptosis were observed. Interestingly, cytoplasmic vacuolation and blockade of autophagy flux were observed after treatment with Rh2 and PPD. Rh2 obviously up-regulated the expression of the LC3II and p62. Furthermore, the increase in lysosomal pH and membrane rupture was observed in Rh2-treated and PPD-treated cells. When HGC-27 cells were pretreated with bafilomycin A1, a specific inhibitor of endosomal acidification, cellular vacuolization was increased, and the cell viability was significantly decreased, which indicated that Rh2-induced lysosome-damage accelerated cell death. Furthermore, data derived from mitochondrial analysis showed that excessive mitochondrial reactive oxygen species (ROS) and dysregulation of mitochondrial energy metabolism were caused by Rh2 and PPD treatment in HGC-27 cells. Taken together, these phenomena indicated that Rh2 and PPD inhibited HCG-27 cells proliferation by inducing mitochondria damage, dysfunction of lysosomes, and blockade of autophagy flux. The number of glycosyl groups at C-3 position could have an important effect on the cytotoxicity of Rg3, Rh2 and PPD.

Suppressing vanadium crossover using sulfonated aromatic ion exchange membranes for high performance flow batteries

Novel ion exchange membrane with just the right width of selective aqueous ionic domain (&lt;0.6 nm) and unique functionalities show extraordinary ion selectivity. These unique ion transport properties of our membrane is reflected in a remarkable flow battery performance.

A dual lane piezoelectric ring bender actuated nozzle-flapper servo valve for aero engine fuel metering

Amongst many other high performance flow control applications, servo valves are used to control aero engines by metering the fuel delivered from the fuel pump. Conventionally, a fuel metering servo valve has a pilot stage with an electromagnetic torque motor moving a flapper which differentially restricts a pair of nozzles to create a hydraulic signal (i.e. a pressure difference). These valve pilot stages use mature, optimised technology such that to achieve improvements requires a novel approach. Torque motors in particular present reliability and manufacturing difficulties, and news solutions should ultimately allow a reduction in manual assembly and set-up, improve repeatability, and eliminate failures associated with fine wire devices. In this paper, a pilot stage actuated by piezoelectric ring benders is proposed, designed, built and tested, and test results are compared with a model used to predict pressure-flow characteristics. A particular challenge is the need to include redundancy, and thus a pair of ring benders is used, allowing isolation between duplicated electrical control channels. Another challenge is the mounting of the ring bender, which has to flex to allow the outer edge of the ring bender to deform, yet be stiff enough to adequately react against generated forces. O-ring mounts made from three different elastomer materials are compared in this study. In aerospace, an added complication is the large range of fuel temperature; F70 fluorosilicone O-rings have been chosen with this in mind, and successfully demonstrated in the range −50 °C to +180 °C. With one active and one inactive ring bender to simulate a failure condition, the new dual lane pilot stage achieves +/−50 μm displacement under test, giving control port flows up to +/−0.6 l min−1, and a control port pressure variation of 40 bar using a 100 bar supply pressure difference (supply minus return pressure). This research establishes that a piezoelectric aero engine fuel valve is feasible, and in particular, that piezoelectric ring bender actuators with elastomeric mountings are highly suited to this application.

(Invited) Recent Progress in Organic-Based Aqueous Flow Batteries

The ability to store large amounts of electrical energy is of increasing importance with the growing fraction of electricity generation from intermittent renewable sources such as wind and solar. Flow batteries show promise because the designer can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all electro-active species in fluids. Wide-scale utilization of flow batteries is limited by the abundance and cost of these materials, particularly those utilizing redox-active metals such as vanadium or precious metal electrocatalysts. We have developed high performance flow batteries based on the aqueous redox behavior of small organic and organometallic molecules, e.g. [1-10]. These redox active materials can be inexpensive and exhibit rapid redox kinetics and long lifetimes, although short lifetimes are more common [7]. We have developed new protocols for measuring capacity fade rates and have discovered that the capacity fade rate is typically determined by the molecular calendar life, which can depend on state of charge, but is independent of the number of charge-discharge cycles imposed [7]. We will report the performance of the few chemistries with long enough calendar life, or the potential for acquiring long enough calendar life [9], for practical application in stationary storage. [1] B. Huskinson, M.P. Marshak, C. Suh, S. Er, M.R. Gerhardt, C.J. Galvin, X. Chen, A. Aspuru-Guzik, R.G. Gordon and M.J. Aziz, "A metal-free organic-inorganic aqueous flow battery", Nature 505, 195 (2014), http://dx.doi.org/10.1038/nature12909[2] K. Lin, Q. Chen, M.R. Gerhardt, L. Tong, S.B. Kim, L. Eisenach, A.W. Valle, D. Hardee, R.G. Gordon, M.J. Aziz and M.P. Marshak, "Alkaline Quinone Flow Battery", Science 349, 1529 (2015), http://dx.doi.org/10.1126/science.aab3033[3] K. Lin, R. Gómez-Bombarelli, E.S. Beh, L. Tong, Q. Chen, A.W. Valle, A. Aspuru-Guzik, M.J. Aziz, and R.G. Gordon, "A redox flow battery with an alloxazine-based organic electrolyte", Nature Energy 1, 16102 (2016). http://dx.doi.org/10.1038/nenergy.2016.102[4] E.S. Beh, D. De Porcellinis, R.L. Gracia, K.T. Xia, R.G. Gordon and M.J. Aziz, "A Neutral pH Aqueous Organic/Organometallic Redox Flow Battery with Extremely High Capacity Retention", ACS Energy Letters 2, 639 (2017). http://dx.doi.org/10.1021/acsenergylett.7b00019[5] Z. Yang, L. Tong, D.P. Tabor, E.S. Beh, M.-A. Goulet, D. De Porcellinis, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, "Alkaline benzoquinone aqueous flow battery for large-scale storage of electrical energy” Advanced Energy Materials 2017, 1702056 (2017). http://dx.doi.org/10.1002/aenm.201702056[6] D.G. Kwabi, K. Lin, Y. Ji, E.F. Kerr, M.-A. Goulet, D. DePorcellinis, D.P. Tabor, D.A. Pollack, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, “Alkaline Quinone Flow Battery with Long Lifetime at pH 12” Joule 2, 1907 (2018). https://doi.org/10.1016/j.joule.2018.07.005[7] M.-A. Goulet & M.J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”, J. Electrochem. Soc. 165, A1466 (2018). http://dx.doi.org/10.1149/2.0891807jes[8] Y. Ji, M.-A. Goulet, D.A. Pollack, D.G. Kwabi, S. Jin, D. DePorcellinis, E.F. Kerr, R.G. Gordon, and M.J. Aziz, “A phosphonate-functionalized quinone redox flow battery at near-neutral pH with record capacity retention rate” Advanced Energy Materials 2019 1900039; https://doi.org/10.1002/aenm.201900039[9] M.-A. Goulet, L. Tong, D.A. Pollack, D.P. Tabor, E.E. Kwan, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, “Extending the lifetime of organic flow batteries via redox state management” Journal of the American Chemical Society 141, in press (2019); https://doi.org/10.1021/jacs.8b13295[10] http://aziz.seas.harvard.edu/electrochemistry

Additively manufactured, highly-uniform flow distributor for process intensification

The ability of flow distributors to achieve high flow uniformity over multiple outlet channels is fundamental to the scalability of the synthesis of pharmaceuticals, polymers, fine chemicals, nanoparticles, and medical devices for drug delivery. Recent developments in the field of additive manufacturing (AM) have significantly increased the range of manufacturable geometries and materials, enabling the construction of high-performance flow distribution devices. Such devices can be manufactured at a wide range of scales (from microns to meters) and from a variety of metal and polymer materials. In this work, we describe a flow distribution system based on a fractal bifurcation scheme which achieves high outlet flow uniformity and packing density, while satisfying additive manufacturing constraints. Performance is predicted using an extensive numerical study and subsequently validated using experimental testing of additively manufactured prototypes. The experimental results confirm the predicted high flow uniformity. The resulting flow distribution system has the potential for use in a wide range of applications.

A new methodology for preliminary design of centrifugal impellers with prewhirl

The overall trend of centrifugal compressor design is to strive for high aerodynamic performance and high flow capacity products. A new methodology is derived to implement a preliminary design for high flow capacity centrifugal impeller with and without prewhirl. First, several new non-dimensional equations connecting impeller geometric and aerodynamic parameters are derived for the maximum flow capacity. The effects of prewhirl on mass flow function, inlet diameter ratio and work coefficient are discussed, respectively. Then, based on these equations, a series of design diagrams are drawn to extract the universal rules in centrifugal impeller design with prewhirl. Some physical limits of design maps are also discussed. Finally, the throat area of impeller is discussed under prewhirl, and the matching principle between prewhirl impeller and vaned diffuser is derived and validated. The proposed method can be used to design a new centrifugal compressor, or to evaluate the design feasibility and the challenge of a given design specification.

Effect of thermal and shear stresses in the spray drying process on the stability of siRNA dry powders

Pulmonary delivery of small interfering RNAs (siRNAs) has shown promising results for the treatment of lung diseases with gene disorders. The aim of this work was to evaluate the effect of processing-induced thermal and shear stresses during the spray drying process on the solid-state properties, the chemical integrity and the bioactivity of spray-dried siRNA powder intended for inhalation. To this end, inhalable siRNA dry powders composed of EGFP-siRNA and mannitol were prepared by using a lab-scale spray drier. Scanning electron microscopy (SEM), laser diffraction, and X-ray powder diffraction (XRPD) were used to characterize the solid-state properties of the spray-dried siRNA-mannitol powders. High performance liquid chromatography (HPLC) and flow cytometry were exploited to assess the chemical stability and cellular transfection efficiency of siRNA formulations, respectively. The results showed that the spray-dried particles changed from spherical to irregular shape with an increase in the inlet temperature. The high inlet temperature and intensive atomization conditions resulted in more agglomerates in the spray-dried particles. XRPD analysis indicated that the presence of siRNA affected the polymorphic form of mannitol in the spray-dried powder. Compromised chemical stability and cell transfection efficiency of siRNA were observed with an increase in the thermal stress and shear stress during the spray drying process. The chemical stability of siRNA in liquid state was more prone to thermal stress when compared to the stability in the solid-state. In conclusion, stable siRNA based particles for inhalation purposes could be produced using the spray drying technology.

Scalable and Efficient Electrochemical Exfoliation of Graphite Felt As High-Performance Flow Battery Electrode

Mass production of highly active graphite felt (GF) electrode is necessary to attain high power density and energy efficiency, which is essential to reduce the cost and enable the extensive industrial application. Herein, for the first time, we report a rapid and scalable electrochemical exfoliation of the GF in aqueous solution by breaking the weak van der Waals forces between the greaphitic layers through anion intercalation. The expansion of the graphite layers creates a distinctive layer by layer structure and introduces sufficient functional groups that intensifies the abundance of electrochemically active surface area resulting enhanced kinetics at the electrode-electrolyte interface and improved wettability enabling better electrolyte accessibility. Consequently, a rapid and reversible redox reactions with minimized overpotential and high volumetric capacity was achieved. In addition, the exfoliated GF (E-GF) electrode deliver voltage and energy efficiencies of 98.53 and 90.96 % at 40 mA cm-2 and 61.86 and 52.90 % at a high current density of 200 mA cm-2, individually. Compared to the traditional GF treatment method, by eliminating the high temperature and high energy consuming synthesis processes, our approach of electrochemical exfoliation is much faster and energy efficient. These results suggest the enormous potential of the exfoliated GF owing to its excellent electrochemical activity combined with its rapid, facile, and scalable nature.

Obstructed flow field designs for improved performance in vanadium redox flow batteries

In this study, we have investigated the effects of varying flow channel depths and addition of various channel obstructions on the electrochemical performance and pumping power requirements of vanadium redox flow batteries (VRFBs). Specifically, 3D-printed ramps and prismatic obstructions were inserted into the channels of interdigitated flow field (IDFF) and parallel flow field (PFF) designs to observe the effect of non-uniform channel depth on the mass transport properties of open- and closed-ended flow channels. Results were compared with conventional flow field geometries. Integration of ramps into the closed-ended (i.e., IDFF) flow channels resulted in 15% improvement in peak power density (PPD) at a flow rate of 50 mL min−1. Addition of ramps to IDFF has also resulted in a significant 40% drop in required pumping pressure due to guided and gradual delivery of the electrolyte to the electrode plane. In addition, the effects of varying channel depths in open-ended (i.e., PFF) channels were found to be much more drastic with improvements in PPD up to 150%. Overall, findings of this study highlight the significance of varying channel depths on improving the mass transport characteristics of VRFBs and offer an alternative approach for design of high-performance flow cells.

&lt;italic&gt;NFVactor&lt;/italic&gt;: A Resilient NFV System Using the Distributed Actor Model

Resilience functionality, including failure resilience and flow migration, is of pivotal importance in practical network function virtualization (NFV) systems. However, existing failure recovery procedures incur high packet processing delay due to heavyweight process checkpointing, while flow migration has poor performance due to centralized control. This paper proposes NFVactor , a novel NFV system that aims to provide lightweight failure resilience and high-performance flow migration. NFVactor enables these by using actor model to provide a per-flow execution environment, so that each flow can replicate and migrate itself with improved parallelism, while the efficiency of the actor model is guaranteed by a carefully designed runtime system. Moreover, NFVactor achieves transparent resilience: once a new network function (NF) is implemented for NFVactor , the NF automatically acquires resilience support. Our evaluation result shows that NFVactor achieves 10-Gbps packet processing, flow migration completion time that is 144 times faster than the existing system, and packet processing delay stabilized at around 20 $\mu \text{s}$ during replication.