It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
Chemical Vapour Deposition is a Chemical Synthesis route of Nanomaterials. Specially thin films like Graphene and Carbon NanoTubes are grown by this method.
This presentation includes basis of lithography i.e. (photo-lithography e-beam lithography) in nano-lithography includes (AFM, Soft, NIL and DPN lithography)
A key vacuum deposition technique for making highly homogenous and high-performance solid-state thin films and materials is Chemical vapor deposition. The types of CVD systems and their key applications would also be discussed in this presentation. It is a key bottom-up processing technique, widely used in graphene fabrication, also the fabrication of various oxides, nitrides is possible, with this technique.
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
Chemical Vapour Deposition is a Chemical Synthesis route of Nanomaterials. Specially thin films like Graphene and Carbon NanoTubes are grown by this method.
This presentation includes basis of lithography i.e. (photo-lithography e-beam lithography) in nano-lithography includes (AFM, Soft, NIL and DPN lithography)
A key vacuum deposition technique for making highly homogenous and high-performance solid-state thin films and materials is Chemical vapor deposition. The types of CVD systems and their key applications would also be discussed in this presentation. It is a key bottom-up processing technique, widely used in graphene fabrication, also the fabrication of various oxides, nitrides is possible, with this technique.
Hot wall reactor is a high temperature chamber in which the substrate is placed for coating. In this reactor including the substrate, all other parts (inlet and outlet tubes) inside the chamber get coated.
This document gives information about the vapor deposition i.e. (CVD and PVD) on tools, the way these tools manufactured and what affects they produce during usage? When they are used in different manufacturing operations? High material removal rate, good surface finish and high productivity rate are the needs of manufacturing industry i.e. actually an “efficient tool”. So, this document discuss about these tools.
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.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
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.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
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.
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 - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” 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.
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.
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 – 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 : 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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s 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 Io’s 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 Io’s surface using adaptive
optics at visible wavelengths.
2. Background
The formation of soot due to incomplete
oxidation of firewood since prehistoric
times is probably the oldest example of
deposition using CVD.
Patent literature by de Lodyguine in 1893 on the deposition of W onto carbon
lamp filaments through the reduction of WCl6 by H2 lead to the industrial
exploitation of CVD.
CVD involves the dissociation and/or chemical
reactions of gaseous reactants in an activated (heat, light, plasma)
environment, followed by the formation of a stable solid product.
2
3. 3
What is CVD?
Chemical vapor deposition (CVD) is a process whereby a solid
material is deposited from a vapor by a chemical reaction
occurring on or in the vicinity of a normally heated substrate
surface.
The solid material is obtained as a coating, a powder, or as single
crystals.
By varying the experimental conditions—substrate material,
substrate temperature, composition of the reaction gas mixture,
total pressure gas flows, etc.—materials with different properties
can be grown.
CVD is an example for Solid-Vapor Reaction.
4. Main Components of CVD Equipment
The role of this component is to generate vapour precursors and
then deliver to the reactor.
The design of the CVD reactor depends on whether the starting
material is solid, liquid or gas.
The sublimation of a solid precursor depends on surface area of the
solid and contact time.
Liquid sources often use a bubbler to vaporise the reactants, and a
carrier gas (reactive gases such as H2 or inert gases such as Ar) to
transport the vaporised reactants into the reactor.
4
1. Chemical vapour precursor supply system
5. 2. CVD reactors
Hot-wall reactor:
In this the substrate (wafer) and the walls of the reactor are heated, i.e. a
homogeneous temperature is maintained inside the reaction chamber.
Disadvantage of hot-wall reactor
Contamination
Cold-wall reactor:
This reactors uses heating systems that minimize the heating up of the reactor
walls while the wafer is being heated up. The temperature is not homogeneous
inside the reaction chamber.
Disadvantage of cold-wall reactor
It is difficult to get a uniform layer of the film.
5
6. 3. The effluent gas handling system
This component consists of a neutralizing part for the exhaust
gases, and/or a vacuum system to provide the required reduced
pressure for the CVD process that performs at low pressure or high
vacuum during deposition.
The unreacted precursors and corrosive by-products such as HCl
are neutralised or trapped using a liquid nitrogen trap.
Inflammable gases such as hydrogen are burned off.
Unreacted expensive precursors may be collected at the outlet and
recycled.
6
7. 7
CVD Equipment
In a typical CVD process, the substrate is exposed to one or more
volatile precursors which react and decompose on the substrate
surface to produce the desired deposit.
During this process, volatile by-products are also produced,
which are removed by gas flow through the reaction chamber.
8. Steps Involved
8
Transport of
reactants by
forced
convection to
the deposition
region.
Desorption of
by-products
from the
surface.
Transport of
by-products by
diffusion.
Transport of
by-products by
forced
convection
away from the
deposition
region.
Transport of
reactants by
diffusion from
the main gas
stream to the
substrate
surface.
Adsorption of
reactants in
the substrate
(wafer)
surface.
Chemical
decomposition
and other
surface
reactions take
place.
9. 9
Mechanism
Main Gas Flow
Gas Phase
Reaction
Transport to
Surface
Surface Diffusion
Adsorption of Film Precursor
Step Growth
Nucleation and Island Growth
Desorption of
Precursor
Desorption of
Volatile Surface
Reaction Products
11. 11
Atmospheric pressure chemical vapour deposition (APCVD)
It works at atmospheric pressure.
It is used to deposit a layer of material typically several
micrometers thick onto a wafer or other type of substrate.
It is also used as a surface finishing process for items such as tools
and turbine blades to improve lifetime and performance.
Since a vacuum system is not required, APCVD systems have a
relatively low operating cost.
APCVD has inherently poor utilization.
APCVD is extremely susceptible to oxidation due to the greater
gas density and residence times.
12. 12
LPCVD coatings exhibit excellent uniformity, high purity, and
good step coverage.
It works at sub-atmospheric pressures. Reduced pressures tend
to reduce unwanted gas-phase reactions and improve film
uniformity across the wafer.
The lower pressure increases the precursor diffusion through the
gas and the mass transfer rate of the gaseous reactants becomes
higher than the surface-reaction rate.
The pressure for LPCVD is usually around 10-1000 Pa while
standard atmospheric pressure is 101,325 Pa.
Low pressure chemical vapour deposition (LPCVD)
13. Metal-organic chemical vapour deposition (MOCVD)
Metal-organic compounds are used as molecular precursors to
deposit, a wide variety of thin film materials for new industrial
applications.
The great advantage of MOCVD precursors are their high
volatility at moderate to low temperatures, therefore reaction
temperatures are lower (750 to 1100 K) than conventional CVD.
The main disadvantages are the precursors tend to be very
expensive and are very volatile. When reactive liquids are used
they require accurate pressure control and are difficult to purify.
13
14. 14
Laser chemical vapour deposition (LCVD)
LCVD uses a focussed laser beam to heat the substrate.
It also has the ability to locally heat a part of the substrate while
passing the reactant gas, thereby inducing film deposition by
locally driving the CVD reaction at the surface.
It is used to deposit microscale solid patterns or three
dimensional structures on the surface of a substrate by a
localized, single step process.
15. Plasma-enhanced chemical vapour deposition (PECVD)
PECVD is used to deposit SiO2, Si3N4 (SixNy), SixOyNz and
amorphous Si films.
Plasma can be used to decompose a molecule that will not
decompose at a reasonable elevated temperature.
It can be used to decompose a thermally unstable molecule but
at a much lower temperature.
In plasma CVD substrates that cannot tolerate high
temperatures, such as polymers, can be used, where substrate
temperatures range from 100 to 500°C.
15
16. 16
Advantages
CVD films are generally quite conformal, i.e., the ability of a film
to uniformly coat a topographically complex substrate.
Versatile –any element or compound can be deposited.
High purity can be obtained.
High density – nearly 100% of theoretical value.
CVD films are harder than similar materials produced using
conventional ceramic fabrication processes.
Material formation well below the melting point.
Economical in production, since many parts can be coated at the
same time.
17. 17
Disadvantages
o Chemical and safety hazards caused by the use of toxic,
corrosive, flammable and/or explosive precursor. Therefore extra
steps have to be taken in the handling of the precursors and in
the treatment of the reactor exhaust.
o High deposition temperatures (often greater than 600 °C) are
often unsuitable for structures already fabricated on substrates.
o Restrictions on the kind of substrates that can be coated.
o It leads to stresses in films deposited on materials with different
thermal expansion coefficients, which can cause mechanical
instabilities in the deposited films.
18. 18
Applications
Coatings – Coatings for a variety of applications such as wear
resistance, corrosion resistance, high temperature protection.
Semiconductors and related devices – Integrated circuits, sensors
and optoelectronic devices.
Fiber optics – for telecommunication.
Used in the microelectronics industry to make films serving as
dielectrics, conductors, passivation layers, oxidation barriers, and
epitaxial layers.
HVPE has become the favored method for the deposition of GaN because of its high deposition rate and low defect density
Plasma is a vapour consisting of cations and electrons. It is most easily generated by establishing an electrical discharge through a low-pressure gas.