scholarly journals Alumina Membrane with Hour-Glass Shaped Nanochannels: Tunable Ionic Current Rectification Device Modulated by Ions Gradient

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Shengnan Hou ◽  
Qinqin Wang ◽  
Xia Fan ◽  
Zhaoyue Liu ◽  
Jin Zhai
Keyword(s):  
Ionic Current ◽  
Concentration Gradients ◽  
Alumina Membrane ◽  
Promising Candidate ◽  
Ion Flow ◽  
Pore Opening ◽  
Current Rectification ◽  
Specific Alumina ◽  
And Diffusion

A new alumina membrane with hour-glass shaped nanochannels is reported using the double-side anodization method and the subsequently in situ pore opening procedure, which is applied to develop the tunable ionic current rectification devices that were modulated by ions gradient. By regulating the pH gradient, tunable ionic current rectification properties which are mainly dependent on the asymmetric surface charge density or polarity distribution on the inner walls of the nanochannels can be obtained. The enhanced ionic current rectification properties were presented due to the synergistic effect of the voltage driven ion flow and diffusion driven ion flow with the application of pH and electrolyte concentration gradients. Therefore, such specific alumina nanochannels would be considered as a promising candidate for building bioinspired artificial ion channel systems.

In situ synthesis of a MOFs/PAA hybrid with ultrahigh ionic current rectification

Nanoscale ◽  
2020 ◽  
Vol 12 (22) ◽  
pp. 11899-11907 ◽  
Author(s):  
Fei-Fei Liu ◽  
Ye-Chang Guo ◽  
Wei Wang ◽  
Yu-Ming Chen ◽  
Chen Wang
Keyword(s):  
Ion Transport ◽  
Ionic Current ◽  
In Situ Synthesis ◽  
Current Rectification

A MOFs/PAA hybrid exhibits excellent ionic rectification, which creates an ideal experimental and theoretical platform for precise ion transport.

A novel in-situ model for continuous observation of transient drug concentration gradients across buccal epithelium at the microscopical level

1996 ◽  
Vol 39 (1) ◽  
pp. 71-78 ◽  
Author(s):  
A.J. Hoogstraate ◽  
C. Cullander ◽  
J.F. Nagelkerke ◽  
F. Spies ◽  
J. Verhoef ◽  
...  
Keyword(s):  
Drug Concentration ◽  
Buccal Epithelium ◽  
Continuous Observation ◽  
Concentration Gradients ◽  
Microscopical Level

scholarly journals Can post-mortem MRI be used as a proxy for in vivo? A case study

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Baayla D C Boon ◽  
Petra J W Pouwels ◽  
Laura E Jonkman ◽  
Matthijs J Keijzer ◽  
Paolo Preziosa ◽  
...  
Keyword(s):  
White Matter ◽  
Rating Scales ◽  
Brain Volume ◽  
Brain Mri ◽  
Post Mortem ◽  
Early Onset Alzheimer’S Disease ◽  
And Diffusion

Abstract Post-mortem in situ MRI has been used as an intermediate between brain histo(patho)logy and in vivo imaging. However, it is not known how comparable post-mortem in situ is to ante-mortem imaging. We report the unique situation of a patient with familial early-onset Alzheimer’s disease due to a PSEN1 mutation, who underwent ante-mortem brain MRI and post-mortem in situ imaging only 4 days apart. T1-weighted and diffusion MRI was performed at 3-Tesla at both time points. Visual atrophy rating scales, brain volume, cortical thickness and diffusion measures were derived from both scans and compared. Post-mortem visual atrophy scores decreased 0.5–1 point compared with ante-mortem, indicating an increase in brain volume. This was confirmed by quantitative analysis; showing a 27% decrease of ventricular and 7% increase of whole-brain volume. This increase was more pronounced in the cerebellum and supratentorial white matter than in grey matter. Furthermore, axial and radial diffusivity decreased up to 60% post-mortem whereas average fractional anisotropy of white matter increased approximately 10%. This unique case study shows that the process of dying affects several imaging markers. These changes need to be taken into account when interpreting post-mortem MRI to make inferences on the in vivo situation.

Intracellular diffusion gradients of O2 and ATP

1986 ◽  
Vol 250 (5) ◽  
pp. C663-C675 ◽  
Author(s):  
D. P. Jones
Keyword(s):  
Mathematical Modeling ◽  
High Flux ◽  
Concentration Gradients ◽  
Electron Microscopic ◽  
Intracellular Diffusion ◽  
Metabolite Concentrations ◽  
Major Factors ◽  
Atp Supply ◽  
Endogenous Enzymes

Endogenous enzymes with different subcellular localizations provide in situ probes to study O2 and ATP concentration at various sites within cells. Results from this approach indicate that substantial intracellular concentration gradients occur under some O2- and ATP-limited conditions. These studies, along with electron microscopic analyses and mathematical modeling, indicate that clustering and distribution of mitochondria are major factors in determining the magnitude and location of the concentration gradients. The mitochondria appear to be clustered in sites of high ATP demand to maximize ATP supply under conditions of limited production. The size of such clusters is limited by the magnitude of the O2 gradient needed to provide adequate O2 concentrations for mitochondrial function within the clusters. Thus microheterogeneity of metabolite concentrations can occur in cells without membranal compartmentation and may be important in determining the rates of various high-flux processes.

scholarly journals Active transport of brilliant blue FCF across the Drosophila midgut and Malpighian tubule epithelia

2019 ◽  
Author(s):  
Dawson B.H. Livingston ◽  
Hirva Patel ◽  
Andrew Donini ◽  
Heath A. MacMillan
Keyword(s):  
Traumatic Injury ◽  
Malpighian Tubule ◽  
Malpighian Tubules ◽  
Brilliant Blue ◽  
Barrier Dysfunction ◽  
Concentration Gradients ◽  
Barrier Disruption ◽  
Brilliant Blue Fcf ◽  
Summary Statement

AbstractUnder conditions of stress, many animals suffer from epithelial barrier disruption that can cause molecules to leak down their concentration gradients, potentially causing a loss of organismal homeostasis, further injury or death. Drosophila is a common insect model, used to study barrier disruption related to aging, traumatic injury, or environmental stress. Net leak of a non-toxic dye (Brilliant blue FCF) from the gut lumen to the hemolymph is often used to identify barrier failure under these conditions, but Drosophila are capable of actively transporting structurally-similar compounds. Here, we examined whether cold stress (like other stresses) causes Brilliant blue FCF (BB-FCF) to appear in the hemolymph of flies fed the dye, and if so whether Drosophila are capable of clearing this dye from their body following chilling. Using in situ midgut leak and transport assays as well as Ramsay assays of Malpighian tubule transport, we tested whether these ionoregulatory epithelia can actively transport BB-FCF. In doing so, we found that the Drosophila midgut and Malpighian tubules can mobilize BB-FCF via an active transcellular pathway, suggesting that elevated concentrations of the dye in the hemolymph may occur from increased paracellular permeability, reduced transcellular clearance, or both.Summary StatementDrosophila are able to actively secrete Brilliant blue FCF, a commonly used marker of barrier dysfunction

Effect of linear surface-charge non-uniformities on the electrokinetic ionic-current rectification in conical nanopores

2009 ◽  
Vol 329 (2) ◽  
pp. 376-383 ◽  
Author(s):  
Shizhi Qian ◽  
Sang W. Joo ◽  
Ye Ai ◽  
Marcos A. Cheney ◽  
Wensheng Hou
Keyword(s):  
Surface Charge ◽  
Ionic Current ◽  
Conical Nanopores ◽  
Current Rectification

Oxygen surface exchange and diffusion in mayenite single crystal

2019 ◽  
Vol 21 (44) ◽  
pp. 24740-24748 ◽  
Author(s):  
Anna S. Tolkacheva ◽  
Sergey N. Shkerin ◽  
Natalia M. Porotnikova ◽  
Mikhail V. Kuznetsov ◽  
Sergey V. Naumov ◽  
...  
Keyword(s):  
Single Crystal ◽  
Gas Phase ◽  
Surface Exchange ◽  
And Diffusion ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Oxygen surface exchange and diffusion in Ca12Al14O33±δ single crystal were studied by a unique in situ method based on isotope equilibration in the gas phase.

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