302 research outputs found
Size-based ion selectivity of micropore electric double layers in capacitive deionization electrodes
Capacitive deionization (CDI) is a fast-emerging technology most commonly
applied to brackish water desalination. In CDI, salt ions are removed from the
feedwater and stored in electric double layers (EDLs) within micropores of
electrically charged porous carbon electrodes. Recent experiments have
demonstrated that CDI electrodes exhibit selective ion removal based on ion
size, with the smaller ion being preferentially removed in the case of
equal-valence ions. However, state-of-the-art CDI theory does not capture this
observed selectivity, as it assumes volume-less point ions in the micropore
EDLs. We here present a theory which includes multiple couterionic species, and
relaxes the point ion assumption by incorporating ion volume exclusion
interactions into a description of the micropore EDLs. The developed model is a
coupled set of nonlinear algebraic equations which can be solved for micropore
ion concentrations and electrode Donnan potential at cell equilibrium. We
demonstrate that this model captures key features of the experimentally
observed size-based ion selectivity of CDI electrodes
Water Purification by Shock Electrodialysis: Deionization, Filtration, Separation, and Disinfection
The development of energy and infrastructure efficient water purification
systems are among the most critical engineering challenges facing our society.
Water purification is often a multi-step process involving filtration,
desalination, and disinfection of a feedstream. Shock electrodialysis (shock
ED) is a newly developed technique for water desalination, leveraging the
formation of ion concentration polarization (ICP) zones and deionization shock
waves in microscale pores near to an ion selective element. While shock ED has
been demonstrated as an effective water desalination tool, we here present
evidence of other simultaneous functionalities. We show that, unlike
electrodialysis, shock ED can thoroughly filter micron-scale particles and
aggregates of nanoparticles present in the feedwater. We also demonstrate that
shock ED can enable disinfection of feedwaters, as approximately of
viable bacteria (here \textit{E. coli}) in the inflow were killed or removed by
our prototype. Shock ED also separates positive from negative particles,
contrary to claims that ICP acts as a virtual barrier for all charged
particles. By combining these functionalities (filtration, separation and
disinfection) with deionization, shock ED has the potential to enable more
compact and efficient water purification systems
Performance Metrics for the Objective Assessment of Capacitive Deionization Systems
In the growing field of capacitive deionization (CDI), a number of
performance metrics have emerged to describe the desalination process.
Unfortunately, the separation conditions under which these metrics are measured
are often not specified, resulting in optimal performance at minimal removal.
Here we outline a system of performance metrics and reporting conditions that
resolves this issue. Our proposed system is based on volumetric energy
consumption (Wh/m) and throughput productivity (L/h/m) reported for a
specific average concentration reduction, water recovery, and feed salinity. To
facilitate and rationalize comparisons between devices, materials, and
operation modes, we propose a nominal standard testing condition of removing 5
mM from a 20 mM NaCl feed solution at 50% water recovery for CDI research.
Using this separation, we compare the desalination performance of a
flow-through electrode (fte-CDI) cell and a flow between membrane (fb-MCDI)
device, showing how significantly different systems can be compared in terms of
generally desirable desalination characteristics. In general, we find that
performance analysis must be considered carefully so to not allow for ambiguous
separation conditions or the maximization of one metric at the expense of
another. Additionally, for context we discuss a number of important underlying
performance indicators and cell characteristics that are not performance
measures in and of themselves but can be examined to better understand
differences in performance
3-D Nanofibrous Electrospun Multilayered Construct is an Alternative ECM Mimicking Scaffold
Abstract Extra cellular matrix (ECM) is a natural cell environment, possesses complicated nano-and macroarchitecture. Mimicking this three-dimensional (3-D) web is a challenge in the modern tissue engineering. This study examined the application of a novel 3-D construct, produced by multilayered organization of electrospun nanofiber membranes, for human bone marrow-derived mesenchymal stem cells (hMSCs) support. The hMSCs were seeded on an electrospun scaffold composed of poly e-caproloactone (PCL) and collagen (COL) (1:1), and cultured in a dynamic flow bioreactor prior to in vivo implantation. Cell viability after seeding was analyzed by AlamarBlue TM Assay. At the various stages of experiment, cell morphology was examined by histology, scanning electron microscopy (SEM) and confocal microscopy
Economic downturn results in tick-borne disease upsurge
<p>Abstract</p> <p>Background</p> <p>The emergence of zoonoses is due both to changes in human activities and to changes in their natural wildlife cycles. One of the most significant vector-borne zoonoses in Europe, tick-borne encephalitis (TBE), doubled in incidence in 1993, largely as a consequence of the socio-economic transition from communism to capitalism and associated environmental changes.</p> <p>Methods</p> <p>To test the effect of the current economic recession, unemployment in 2009 and various socio-economic indices were compared to weather indices (derived from principal component analyses) as predictors for the change in TBE case numbers in 2009 relative to 2004-08, for 14 European countries.</p> <p>Results</p> <p>Greatest increases in TBE incidence occurred in Latvia, Lithuania and Poland (91, 79 and 45%, respectively). The weather was rejected as an explanatory variable. Indicators of high background levels of poverty, e.g. percent of household expenditure on food, were significant predictors. The increase in unemployment in 2009 relative to 2008 together with 'in-work risk of poverty' is the only case in which a multivariate model has a second significant term.</p> <p>Conclusion</p> <p>Background socio-economic conditions determine susceptibility to risk of TBE, while increased unemployment triggered a sudden increase in risk. Mechanisms behind this result may include reduced resistance to infection through stress; reduced uptake of costly vaccination; and more exposure of people to infected ticks in their forest habitat as they make greater use of wild forest foods, especially in those countries, Lithuania and Poland, with major marketing opportunities in such products. Recognition of these risk factors could allow more effective protection through education and a vaccination programme targeted at the economically most vulnerable.</p
IFNAR1-Signalling Obstructs ICOS-mediated Humoral Immunity during Non-lethal Blood-Stage Plasmodium Infection
Funding: This work was funded by a Career Development Fellowship (1028634) and a project grant (GRNT1028641) awarded to AHa by the Australian National Health & Medical Research Council (NHMRC). IS was supported by The University of Queensland Centennial and IPRS Scholarships. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Striking augmentation of hematopoietic cell chimerism in noncytoablated allogeneic bone marrow recipients by flt3 ligand and tacrolimus
The influence of granulocyte-macrophage colony-stimulating factor (GM- CSF) and the recently identified hematopoietic stem-progenitor cell mobilizing factor flt3 ligand (FL) on donor leukocyte microchimerism in noncytodepleted recipients of allogeneic bone marrow (BM) was compared. B10 mice (H2b) given 50 x 106 allogeneic (B10.BR [H2(k)]) BM cells also received either GM-CSF (4 μg/day s.c.), FL (10 μg/day i.p.), or no cytokine, with or without concomitant tacrolimus (formerly FK506; 2 mg/kg) from day 0. Chimerism was quantitated in the spleen 7 days after transplantation by both polymerase chain reaction (donor DNA [major histocompatibility complex class II; I-E(k)]) and immunohistochemical (donor [I-E(k+)] cell) analyses. Whereas GM-CSF alone significantly augmented (fivefold) the level of donor DNA in recipients' spleens, FL alone caused a significant (60%) reduction. Donor DNA was increased 10-fold by tacrolimus alone, whereas coadministration of GM-CSF and tacrolimus resulted in a greater than additive effect (28-fold increase). A much more striking effect was observed with FL + tacrolimus (>125-fold increase in donor DNA compared with BM alone). These findings were reflected in the relative numbers of donor major histocompatibility complex class II+ cells (many resembling dendritic cells) detected in spleens, although quantitative differences among the groups were less pronounced. Evaluation of cytotoxic T lymphocyte generation by BM recipients' spleen cells revealed that FL alone augmented antidonor immunity and that this was reversed by tacrolimus. Thus, although FL may potentiate antidonor reactivity in nonimmunosuppressed, allogeneic BM recipients, it exhibits potent chimerism-enhancing activity when coadministered with recipient immunosuppressive therapy. This property of FL may offer considerable potential for the augmentation of microchimerism, with therapeutic implications for organ allograft survival and tolerance induction
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