Class XII Electrochemistry - Nernst equation.Arunesh Gupta
Â
Introduction, application of electrochemistry, metallic conduction & electrolytic conduction, electrolytes, electrochemical cell & electrolytic cell, Galvanic cell (Daniell cell), Standard reduction & oxidation potential, SHE as reference electrode, Standard emf of a cell or standard cell potential, Electrochemical series & its application, Nernst equation, Relationship between (i) Standard cell potential & equilibrium constant (ii) standard cell potential & standard Gibbs energy, some numerical problems.
Class XII Electrochemistry - Nernst equation.Arunesh Gupta
Â
Introduction, application of electrochemistry, metallic conduction & electrolytic conduction, electrolytes, electrochemical cell & electrolytic cell, Galvanic cell (Daniell cell), Standard reduction & oxidation potential, SHE as reference electrode, Standard emf of a cell or standard cell potential, Electrochemical series & its application, Nernst equation, Relationship between (i) Standard cell potential & equilibrium constant (ii) standard cell potential & standard Gibbs energy, some numerical problems.
A potentiostat is an electronic instrument that measures and controls the voltage difference between a Working Electrode and a Reference Electrode. It measures the current flow between the Working and Counter Electrodes.
Potentiometry: Electrical potential, electrochemical cell, reference electrodes, indicator
electrodes, measurement of potential and Ph, construction and working of electrodes,
Potentiometric titrations, methods of detecting end point, Karl Fischer titration.
Observation of Ioâs Resurfacing via Plume Deposition Using Ground-based Adapt...SĂŠrgio Sacani
Â
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Ioâs surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Ioâs trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Ioâs surface using adaptive
optics at visible wavelengths.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Â
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.Â
 Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Â
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other  chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released. Â
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules -Â a chemical called pyruvate. A small amount of ATP is formed during this process.Â
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to âburnâ the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP.  Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.Â
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.Â
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 â 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : Â cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana LuĂsa Pinho
Â
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Multi-source connectivity as the driver of solar wind variability in the heli...SĂŠrgio Sacani
Â
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASAâs Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly AlfvĂŠnic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5âau
but are applicable to near-Earth observatories.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Â
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), NiĹĄ, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Richard's aventures in two entangled wonderlandsRichard Gill
Â
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
2. Electrochemistry
Electrochemistry â Chemical change accompanied by the
exchange or movement of electrons. It is the study of
electron-transfer reactions.
Ox + ne- Red
Oxidation: Loss of electrons Fe Fe2+ + 2 e-
Reduction: Gain of electrons 2H+ + 2e- H2
4. Divide and Conquer
Electrochemists think of Half Reactions
â Separate Oxidation and Reduction
â Each can be studied independently
â May happen in different places!
⢠Fuel Cell or Battery
Fe + 2 H+
Fe
2 H+ + 2e-
Fe+2 + H2
Fe+2 + 2e-
H2
6. Electrochemical Quantities
⢠Current (i): Electron flow as a result of a redox reaction
â Current measures the RATE of the reaction (electrons per
second)
â Anodic (oxidation) and cathodic (reduction) currents have
different polarity (signs).
â Unit: ampere ( 1 A = 6 x 1018 electrons/s )
⢠Charge (Q): Total number of electrons
â Charge measures the AMOUNT of the reaction.
â Unit: coulomb (1 C = 6 x 1018 electrons = 1A for 1s )
Unit: faraday ( 1 F = 1 mole of e- = 6 x 1023 e-
= 96 487 C )
7. Electrochemical Quantities
⢠Potential (E):
â Voltage measures the ENERGY of the reaction
â Voltage is the equivalent of wavelength in optical
spectroscopy. Potential is the driving force for the redox
reaction.
â Unit: volt ( 1 V = 1 joule / coulomb )
â The potential is related to the thermodynamics of the
system:
DG = -n F E (negative DG is spontaneous)
joule/mole = (# e-) (coulombs/mole) (joule/coulomb)
8. Electrochemical Quantities
⢠Potential (E)
â You can only measure a DIFFERENCE in potential/voltage
⢠Between What and What?
⢠What is the reference point or âGround Stateâ
â Need a Reference Electrode to provide that reference point!!
⢠Zero Volts is NOT âNothingâ
â Oxidation or reduction can happen at any potâl !
⢠+, â, or zero
â It depends on the Reference Electrode used!
⢠Use of a Reference Electrode allows the electrochemist focus on either
Half-Reaction
â Reaction at Working Electrode!
9. Quick Review !
⢠Current â Rate of Reaction
⢠Charge â Amount of Material
⢠Voltage â Energy (Difference) of Reaction
⢠Reference Electrode â Ground State/Reference
⢠Oxidation and Reduction â Always Paired!
⢠Half-Reactions
⢠Oxidation â Anode
⢠Reduction â Cathode
? Working Electrode / Counter Electrode ?
Which is the Anode? Which is the Cathode?
⢠Focus Our Interest on the Working Electrode
10. Potential and Current Conventions
+ Anodic, âOxidationâ
Current
Working
Electrode
Potential
â Cathodic, âReductionâ
More Oxidizing,âNobleâMore Reducing, âActiveâ
Current polarity depends upon potentiostat manufacturer,
geography, application!
EOpen Circuit, imeas = 0
+_
11. Range of Potential and Current
⢠With the exception of Lithium batteries, 90% of electrochemical
experiments take place within +/- 2 volts. Including batteries, the
potential rarely exceeds +/- 10 volts for a single cell. (Except for
titanium!)
⢠Current can vary from tens or hundreds of amps to femtoamps (10-15
amps). Thatâs 15-17 orders of magnitude! Modern potentiostats are
capable of auto-ranging the current over 9-10 decades of current.
(Important for Corrosion)
Actual current at a Working Electrode depends on the current density,
area, and nature of the experiment.
12. Electrochemical Techniques
In electrochemistry, there are three variables: potential (E), current (i),
and time.
⢠Potentiometric: Measure E (pH Meter) at i=0
⢠Zero Resistance Ammeter (ZRA): Measure i between two connected
electrodes.
Apply an excitation, measure a response.
⢠Potentiostatic: Control E, Measure i (i vs E, i vs t)
⢠Galvanostatic: Control i, Measure E (E vs i, E vs t)
13. Model of the Electrode-Solution Interface or Double
Layer*
*âElectrochemical Methodsâ, Bard and Faulkner
In electrochemistry,
everything of interest
takes place at the
interface!
14. Electrode Processes
⢠Faradaic Process: Current flow as a result
of electron transfer (charge transfer, redox
reaction).
⢠Non-Faradaic Process: Current flow as a
result of the capacitive nature of an
electrode. This is termed the double-layer
capacitance, Cdl.
15. Capacitance of an Electrode
⢠A capacitor is a circuit element composed of two conductors separated by a
dielectric material.
⢠C (Farads) = q(Coulombs)/E (Volts)
⢠A charged electrode in contact with an electrolyte behaves like a capacitor
because of the structure of the electrical double layer at the electrode-
solution interface.
⢠When the applied potential on the electrode is changed, a charging current
will flow. This current is small but measurable.
⢠A typical double-layer capacitance of an electrode is 10-40 ďF/cm2.
⢠The double-layer capacitance, Cdl, is a factor in every electrochemical
experiment.
16. Potentiostatic Experiments
⢠A potentiostat controls the potential between the Working
Electrode and the Reference Electrode while it measures the
current between the Working Electrode and the Counter
Electode.
⢠Most electrochemical experiments are potentiostatic. Because of
the relationship between the potential and the thermodynamics of
the system, potentiostatic experiments are easier to understand.
⢠Change the potential in some systematic way and measure the
current response. The applied potential will force a redox reaction to
occur.
17. The Potentiostatic Experiment
⢠Working Electrode: Electrode Being Studied.
⢠Reference Electrode: Saturated Calomel (SCE) or
Silver-Silver Chloride (Ag/AgCl).
⢠Counter Electrode: Should be Conductive and Inert
(Graphite or Platinum).
⢠Solution May/May Not be Stirred, Deaerated (O2).
⢠Temperature Control Should be Considered
Encouraged!
18. Potentiostatic Experiment
Time
Potential,V
A potentiostatic experiment is performed at a constant potential while
measuring the current. By common usage, it has also come to mean
an experiment in which the potential is stepped into a region where a
faradaic reaction occurs.
19. Analog Potential Scan Experiment
Time
Potential,V
Analog
Scan Rate
mV/sec
In many electrochemical experiments, the potential is
âscannedâ in a linear fashion. Scan rates vary from 0.01
mV/s to 10,000 V/s. Manual (non-computerized) instruments
use an analog ârampâ.
21. Electrolyte Resistance
⢠The goal of the potentiostat is to control the potential of the
Working Electrode vs. a Reference Electrode.
⢠There is always a potential difference (a potential drop) due to
current flow through the resistance in the bulk of the solution.
⢠The resistance of the electrolyte between the Working and
Reference Electrodes causes an error in the Applied Potential.
⢠Eactual = Eapplied - EiR
⢠Placing the Reference Electrode as close as possible to the
surface of the Working Electrode helps, but does not solve the
problem.
22. iR Compensation
⢠To correct for the error in the applied potential, the
potentiostat must compensate for the iR drop in the
solution.
⢠The most common techniques for iR compensation are
current interrupt (for slow experiments) and positive
feedback (for fast experiments).
23. Current Interrupt iR Compensation
⢠The current is briefly (40-200 ďsec) turned off after
each data point.
⢠After interruption, the potential due to iR drop
disappears.
⢠The actual potential at the electrode remains
constant within the time scale of the interruption
because of the capacitive nature of the interface.
⢠To correct, the measured iR error is âaddedâ to the
applied potential.
24. Current Interrupt Timing
E T T
E1
E2
Cell Off
Time
E3
Interrupt Time = 40 â 200 ďsec
DE = Potential Error Due to iR Drop
25. Requirements for Successful
Current Interrupt
⢠Need minimum double layer capacitance
of 20-100 ďFarads
⢠Ru must be less than 1000 ohms
⢠Ratio of Ru to Rp must be less than 10
⢠Scan Rate/Data Acquisition Rate Must be
Slow
26. Positive Feedback iR
Compensation
⢠Somehow Measure R
⢠Add a Signal iR to the Applied Signal
â Multiply I Signal by R with Analog Circuitry
â Add Product to Applied Voltage
⢠Suitable for Rapidly Changing Currents
â Rapidly Changing Voltages
â Fast Scans
â Voltage Steps
27. Positive Feedback- Measure
R⢠Pulse
â 10 - 50 mV Pulse
â Analyze Current Waveform ( RC Decay )
â BAS, PE
⢠EIS !
â High Frequency Limit
â Solution Resistance Only
â EIS Capability in Every PCI4 / FAS2 / Reference
600
⢠If Overcompensate
â Oscillate!
28. Galvanostatic Experiments
⢠A galvanostat controls the current between
the Working and Counter Electrodes
⢠If desired, the potential of the Working
Electrode may be measured vs. a
Reference Electrode
⢠Not as Popular as Potentiostatic
â Hard to Know What Process Consumes the
Current
29. Zero Resistance Ammeter
⢠A ZRA electronically connects two electrodes and
measures the current flow between them. The potential
difference of the couple is measured versus a Reference
Electrode.
⢠The two most important experiments using a ZRA are
electrochemical noise and galvanic corrosion.