1) The recovery from slow inactivation in potassium channels is controlled by buried water molecules in the selectivity filter.
2) Water molecules trap the selectivity filter in an inactive confirmation, explaining the long timescales of recovery from slow inactivation.
3) Removing water molecules speeds up recovery, as shown through experiments using sucrose to remove water from the selectivity filter.
There is one research paper published in the PNAS science journal about role of Aquaporin 3 mediated H2O2 transport in colonic epithelia. Here I try to explain it in easy way with slides. Enjoy it.
There is one research paper published in the PNAS science journal about role of Aquaporin 3 mediated H2O2 transport in colonic epithelia. Here I try to explain it in easy way with slides. Enjoy it.
"Open To The Public": Cultural Institutions, Digital Labor, and Local Network...jkmcgrath
Slides from a talk I gave as part of the "Public Humanities In A Digital Age" panel (organized by Nicky Agate) at ACLA 2016 (Harvard University). Additional context will be provided via a blog post about this talk; I'll update info here with the link when it's up.
Plano de Negócios Oceanic Cosméticos - Janeiro 2016Eliete Cerqueira
Torne-se Um Afiliado Oceanic Cosméticos, Cadastre-se através do link: http://escritorio.oceanic.com.br/u/ElieteCS
escolha o seu pack de afiliação ou entre em contato no site: http://likind.com/oceanic
Ethics in the Work Place www.mannrentoy.comMann Rentoy
www.characterconferences.com
Being Ethical Professionals
About Mann Rentoy
A lecturer from the University of Asia and the Pacific (UA&P), he has taught for more than 30 years.
He is a graduate of the University of Santo Tomas (UST) where he earned a double-degree in AB Journalism and AB Literature, an MA in Creative Writing, and a PhD in Literature.
He was the Founding Executive Director of Westbridge School in Iloilo City. He was in the first batch of graduates of PAREF Southridge School, where he also taught for 15 years, occupying various posts including Principal of Intermediate School, Vice-Principal of High School and Department Head of Religion. As Moderator of “The Ridge”, the official publication of Southridge, he won 9 trophies from the Catholic Mass Media Awards including the first ever Hall of Fame for Student Publication, for winning as the best campus paper in the country for four consecutive years.
He is the Founding Executive Director of “Character Education Partnership Philippines”, or CEP Philippines, an international affiliate of CEP in Washington, DC, USA. As Founder of CEP Philippines, he has been invited to speak all over the country, as well as in Washington D.C., San Diego, California, USA, Colombo, Sri Lanka, and Kuala Lumpur, Malaysia. He also serves as the Founding President of Center for 4th and 5th Rs (Respect & Responsibility) Asia, otherwise known as the Thomas Lickona Institute for Asia. He is probably the most visible advocate of character formation in the country, having spoken to hundreds of schools and universities around the Philippines.
Email us at catalystpds@gmail.com
www.characterconferences.com
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Experimental Investigation on Hypochlorous Acid Water Production using Electr...iosrjce
Available chlorine has an effect on the sterilization and disinfection of a water supply, especially for
drinking water. In order to obtain available chlorine industrially, it is important to generate available chlorine
at high-concentrations with high-efficiency. However, it is difficult to simultaneously attain high concentration
with high-efficiency. In this paper, the optimum operation conditions for available chlorine production are
proposed from the standpoint of high-efficiency. The experiment was conducted using a flow-type reactor with
narrow and parallel electrode plates, even though it lacks a barrier membrane between the plates. The
governing factors are: the electrode plate interval and the flow rate of sodium chloride solution from the
viewpoint of hydrodynamics, and the concentration of sodium chloride of the medium and current density
supplied to the electrode plates from the standpoint of chemical reactions. The production efficiency of the
available chlorine was estimated by the ratio of actually reacted available chlorine to the ideally reacted
available chlorine. The governing factors were examined based on the experimental results. As a result, the
production of available chlorine with high-efficiency is strongly affected by the flow rate as well as the current
density. These results will be useful for producing chlorinated water, called hypochlorous acid water.
ELECTRO DIALYSIS FOR THE DESALINATION OF BACKWATERS IN KERALAcivej
With the declining freshwater source and increase in demand for the potable water need of desalination
have increased. The electrodialysis can be put as an economic substitute for the desalination of the
brackish water. This paper deals with the assessment of the effect contaminants in the desalination of
natural brackish water using electrodialysis. The contaminants studied were Boron, Sulfate and
Magnesium in the presence of chloride. The study was based on the function of pH at a constant voltage
of 11 V. Magnesium, Chloride, and Sulfate was not affected by the pH variations and was removed to an
efficiency of 94%, 95%, and 74% respectively. But the boron was not removed in neutral pH and showed
a removal efficiency of 41% at pH 10 in an hour. There was significant interference in the removal of the
Chloride ion and Sulfate ion.
Rate limiting interfacial hole transfer in Sb2S3 solid state solar cellskamatlab
view article: http://dx.doi.org/10.1039/C3EE43844A
Solid-state sensitized solar cells (SSCs) utilizing semiconductor absorbers overcome the issues of leakage and evaporation encountered in liquid-junction SSCs, and offer the potential for efficient, low cost photovoltaics. For widespread commercialization these solar cells require higher power conversion efficiency than is currently obtained with state-of-the-art devices. One critical component to this is the efficient extraction of photogenerated charges from the semiconductor absorber material. In this study, we decouple the two steps of hole transfer in the Sb2S3/CuSCN system: diffusion of holes in the Sb2S3 absorber layer, and transfer of these holes across Sb2S3–CuSCN interface. We find that interfacial transfer is the major limiting step in the thin (< 20 nm) Sb2S3 films used for high efficiency Sb2S3 photovoltaics. Decoupling of diffusion and interfacial transfer leads to a deeper understanding of the mechanism of hole transfer. This information has implications for the future design of semiconductor-based SSCs as it points to an important, often neglected interface, the absorber-hole conductor interface, which can play an important role in charge extraction.
Removal of 137Cs from contaminated soil using pilot electrokinetic decontamin...Agriculture Journal IJOEAR
—The removal efficiencies of 137Cs for 10 days were 50-70%. The removal efficiencies according to the elapsed time after 10 days were reduced. When an electric current density of 25-75 mA/cm2, sulfuric acid, nitric acid, acetic acid as electrolyte, a 0.5-2.0 cm/min hydraulic conductivity of soil were applied, respectively, the time required for the removal efficiency of 137Cs to reach 80% was 20-30 days. For improving removal efficiency of 137Cs from contaminated soil, it is necessary to increase an electric current density using sulfuric acid as an electrolyte and to decrease hydraulic conductivity of soil in the soil cell.
"Open To The Public": Cultural Institutions, Digital Labor, and Local Network...jkmcgrath
Slides from a talk I gave as part of the "Public Humanities In A Digital Age" panel (organized by Nicky Agate) at ACLA 2016 (Harvard University). Additional context will be provided via a blog post about this talk; I'll update info here with the link when it's up.
Plano de Negócios Oceanic Cosméticos - Janeiro 2016Eliete Cerqueira
Torne-se Um Afiliado Oceanic Cosméticos, Cadastre-se através do link: http://escritorio.oceanic.com.br/u/ElieteCS
escolha o seu pack de afiliação ou entre em contato no site: http://likind.com/oceanic
Ethics in the Work Place www.mannrentoy.comMann Rentoy
www.characterconferences.com
Being Ethical Professionals
About Mann Rentoy
A lecturer from the University of Asia and the Pacific (UA&P), he has taught for more than 30 years.
He is a graduate of the University of Santo Tomas (UST) where he earned a double-degree in AB Journalism and AB Literature, an MA in Creative Writing, and a PhD in Literature.
He was the Founding Executive Director of Westbridge School in Iloilo City. He was in the first batch of graduates of PAREF Southridge School, where he also taught for 15 years, occupying various posts including Principal of Intermediate School, Vice-Principal of High School and Department Head of Religion. As Moderator of “The Ridge”, the official publication of Southridge, he won 9 trophies from the Catholic Mass Media Awards including the first ever Hall of Fame for Student Publication, for winning as the best campus paper in the country for four consecutive years.
He is the Founding Executive Director of “Character Education Partnership Philippines”, or CEP Philippines, an international affiliate of CEP in Washington, DC, USA. As Founder of CEP Philippines, he has been invited to speak all over the country, as well as in Washington D.C., San Diego, California, USA, Colombo, Sri Lanka, and Kuala Lumpur, Malaysia. He also serves as the Founding President of Center for 4th and 5th Rs (Respect & Responsibility) Asia, otherwise known as the Thomas Lickona Institute for Asia. He is probably the most visible advocate of character formation in the country, having spoken to hundreds of schools and universities around the Philippines.
Email us at catalystpds@gmail.com
www.characterconferences.com
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Experimental Investigation on Hypochlorous Acid Water Production using Electr...iosrjce
Available chlorine has an effect on the sterilization and disinfection of a water supply, especially for
drinking water. In order to obtain available chlorine industrially, it is important to generate available chlorine
at high-concentrations with high-efficiency. However, it is difficult to simultaneously attain high concentration
with high-efficiency. In this paper, the optimum operation conditions for available chlorine production are
proposed from the standpoint of high-efficiency. The experiment was conducted using a flow-type reactor with
narrow and parallel electrode plates, even though it lacks a barrier membrane between the plates. The
governing factors are: the electrode plate interval and the flow rate of sodium chloride solution from the
viewpoint of hydrodynamics, and the concentration of sodium chloride of the medium and current density
supplied to the electrode plates from the standpoint of chemical reactions. The production efficiency of the
available chlorine was estimated by the ratio of actually reacted available chlorine to the ideally reacted
available chlorine. The governing factors were examined based on the experimental results. As a result, the
production of available chlorine with high-efficiency is strongly affected by the flow rate as well as the current
density. These results will be useful for producing chlorinated water, called hypochlorous acid water.
ELECTRO DIALYSIS FOR THE DESALINATION OF BACKWATERS IN KERALAcivej
With the declining freshwater source and increase in demand for the potable water need of desalination
have increased. The electrodialysis can be put as an economic substitute for the desalination of the
brackish water. This paper deals with the assessment of the effect contaminants in the desalination of
natural brackish water using electrodialysis. The contaminants studied were Boron, Sulfate and
Magnesium in the presence of chloride. The study was based on the function of pH at a constant voltage
of 11 V. Magnesium, Chloride, and Sulfate was not affected by the pH variations and was removed to an
efficiency of 94%, 95%, and 74% respectively. But the boron was not removed in neutral pH and showed
a removal efficiency of 41% at pH 10 in an hour. There was significant interference in the removal of the
Chloride ion and Sulfate ion.
Rate limiting interfacial hole transfer in Sb2S3 solid state solar cellskamatlab
view article: http://dx.doi.org/10.1039/C3EE43844A
Solid-state sensitized solar cells (SSCs) utilizing semiconductor absorbers overcome the issues of leakage and evaporation encountered in liquid-junction SSCs, and offer the potential for efficient, low cost photovoltaics. For widespread commercialization these solar cells require higher power conversion efficiency than is currently obtained with state-of-the-art devices. One critical component to this is the efficient extraction of photogenerated charges from the semiconductor absorber material. In this study, we decouple the two steps of hole transfer in the Sb2S3/CuSCN system: diffusion of holes in the Sb2S3 absorber layer, and transfer of these holes across Sb2S3–CuSCN interface. We find that interfacial transfer is the major limiting step in the thin (< 20 nm) Sb2S3 films used for high efficiency Sb2S3 photovoltaics. Decoupling of diffusion and interfacial transfer leads to a deeper understanding of the mechanism of hole transfer. This information has implications for the future design of semiconductor-based SSCs as it points to an important, often neglected interface, the absorber-hole conductor interface, which can play an important role in charge extraction.
Removal of 137Cs from contaminated soil using pilot electrokinetic decontamin...Agriculture Journal IJOEAR
—The removal efficiencies of 137Cs for 10 days were 50-70%. The removal efficiencies according to the elapsed time after 10 days were reduced. When an electric current density of 25-75 mA/cm2, sulfuric acid, nitric acid, acetic acid as electrolyte, a 0.5-2.0 cm/min hydraulic conductivity of soil were applied, respectively, the time required for the removal efficiency of 137Cs to reach 80% was 20-30 days. For improving removal efficiency of 137Cs from contaminated soil, it is necessary to increase an electric current density using sulfuric acid as an electrolyte and to decrease hydraulic conductivity of soil in the soil cell.
1. Recovery from
Slow Inactivation
in K+ Channels
Is Controlled by
Buried Water
Molecules
Jared L. Ostmeyer1, Sudha
Chakrapani2, Eduardo
Perozo1, Benoît Roux1
1University of Chicago, 2Case Western Reserve University
2. Activation Gate Open
Conductive
Filter Inactive Filter
Activation Gate Closed
Conductive Filter
Inactive Filter
Entry into
Inactivation
Recovery
from
Inactivation
time(sec)
Ext [K+] mM
12. Conclusion
Water molecules act as ligands that trap the selectivity filter
in an inactive confirmation when present. This explains the
long timescales of slow-inactivation.
Wild Type Y82A Mutant
13. Luis Cuello
Acknowledgements
Eduardo Perozo
Albert Pan
Sudha Chakrapani
Benoît Roux
NIH Grants:
• R01-GM062342 (B.R)
• R01-GM57846 (E.P.)
NRBSC (Anton Allocation):
• RC2GM093307
INCITE:
• Supercomputing time provided at
Oak Ridge National Laboratories
Editor's Notes
Hello, my name is Jared Ostmeyer.
Today I am going to talk about recovery from slow-inactivation in K+ channels.
It is our conclusion that this process is controlled by water molecules buried inside the protein.
In all K+ channels that exhibit slow-inactivation, current passing through the channel will taper off over time.
It is well known that the loss of current is mediated by some conformation transition taking place in the selectivity filter (LEFT) .
In other words, if we open the activation gate to allow current to pass through, and we wait long enough, we should expect to see the selectivity filter an inactivated state.
We can summarize this process with a simple hypothetical free-energy landscape where the inactive filter is the more stable state.
The process is reversed once the activation gate is closed.
Closing the activation gate promotes recovery from inactivation, returning the selectivity filter back to its original conductive state, so the channel is primed and ready to go again.
The recovery process is extremely slow.
In KcsA, a potassium channel, recovery from slow inactivation takes up to 8 seconds even in the presence of 1M extracellular K+ solution.
Now we can again summarize recovery from inactivation with another hypothetical free-energy landscape.
But this time our hypothetical free-energy landscape for the recovery process is essentially opposite what is was before.
Now I’ve drawn a sizeable free-energy barrier that acts to impede recovery from slow-inactivation because we know this process takes a long time.
Like the title of my talk suggests, we want to study slow-inactivation.
It just so happens that we have X-ray crystal structures of the two endpoints of the recovery process for KCSA.
Here is the selectivity filter from the crystal structure 1K4D.
It features a pinched filter that looks just a little to narrow in the middle for K+ ions to pass through.
Presumably this is a non-conductive state of the selectivity filter.
There was debate over whether or not the pinched filter represented slow inactivated state of the filter.
Just because the conformation looks non-conductive doesn’t mean it actually represents the long lasting inactivated state.
Recently, Luis Cuello obtained X-ray crystal structures of KcsA with open activation gates.
We just saw that when the activation gate is open, the selectivity filter should reach its slow-inactivated state.
It just so happens that the selectivity filter in the open structures is in the same pinched conformation.
Here, I have just superimposed the filter from an open channel on top of the pinched state.
You can see that they are essentially the same.
Thus, the end-stage conformation of the selectivity filter of an open channel matches that of the initial state of the closed channel.
This reinforces the viewpoint that the pinched filter models the structure of the inactivated filter.
Here is the selectivity filter from the crystal structure 1K4C.
It features an obviously conductive filter.
Binding sites for K+ ions line the permeation pathway throughout the entire filter.
There is just one problem.
Here I am again showing you the pinched and conductive filter.
If we superimposed these two structures on top of each other… we see that the difference between the coordinates of the two conformation is subtle.
The largest difference through the permeation pathway of the filter is where the filter pinches shut.
Here, the Cα glycine residues have moved in by an 1Å.
This is an absurdly subtle change.
If we knew nothing about K+ channels other than these two crystal structures of KcsA, we might expect the recovery process could occur spontaneously simply due to thermal fluctuations alone.
It is hard to image why it takes so long for the channel to recover.
To put the timescales in perspective, bacteria can synthesize entire subunits of the channel on the same timescale as the recovery process.
To elucidate what is going on we began by running a 17μs long simulation of the pinched selectivity filter.
We setup the simulation to promote recovery from inactivation in everyway we could.
The activation gate was in a closed conformation, & we bathed the channel in the simulation in 1M KCl solution.
We honestly expected to observe the selectivity filter fluctuate to the width of a conductive filter.
However, over the course of our 17μs long simulation nothing interesting happened.
In the top trace I am showing you the width of the selectivity filter measured as the distance between the Cα atoms on the glycine residues.
As you can see the width of the filter remained at 5.5Å, which is the width of the pinched filter.
The width of the filter never deviated to 8.1Å.
This told us the pinched conformation was stable, at least over the timescale of 17μs.
The bottom trace shows the position of K+ ions along the height of the selectivity filter.
As you can see, K+ ions were never able to reach positions in the center of the selectivity filter.
This told us the pinched filter was indeed non-conductive.
Over on the right I showing you the selectivity filter at the end of the simulation.
We noticed that water molecules had remained behind the selectivity filter throughout the entire simulation.
We then asked the question what was it that was keeping water molecules present behind the filter.
Already, you can see that the traces of the inactivating currents look very different under the applied osmotic stress.
This work was supported by the National Institute of Health through grant R01-GM062342 (J.O. and B.R) and R01-GM57846 (S.C. and E.P.). The authors acknowledge supercomputer time provided by the Oak Ridge National Laboratory via the INCITE program of the Department of Energy. Anton computer time was provided by the National Resource for Biomedical Supercomputing and the Pittsburgh Supercomputing Center through Grant RC2GM093307 from the National Institutes of Health. The Anton machine had been donated generously by David E. Shaw; we are most grateful for the opportunity to use Anton.
![Activation Gate Open
Conductive
Filter Inactive Filter
Activation Gate Closed
Conductive Filter
Inactive Filter
Entry into
Inactivation
Recovery
from
Inactivation
time(sec)
Ext [K+] mM](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)