Silicon is of great interest for use as the anode material in lithium-ion batteries due to its high
capacity. However, certain properties of silicon, such as a large volume expansion during the
lithiation process and the low diffusion rate of lithium in silicon, result in fast capacity
degradation in limited charge/discharge cycles, especially at high current rate. Therefore, the
use of silicon in real battery applications is limited. The idea of using porous silicon, to a large
extent, addresses the above-mentioned issues simultaneously. In this review, we discuss the
merits of using porous silicon for anodes through both theoretical and experimental study.
Recent progress in the preparation of porous silicon through the template-assisted approach
and the non-template approach have been highlighted. The battery performance in terms of
capacity and cyclability of each structure is evaluated.
Our GraphenX products are comprised of single layers of graphene oxide. It is a product of oxidation of graphite through a modified Hummers’ method. In contrast to commercially available graphene oxide sheets which possess lateral size generally less than 5μm, GraphenX are monolayers of oxidized graphene with outstandingly high lateral size (up to 0.1mm), rendering these products as an excellent candidate for diverse applications such as electronics, composite materials, energy and etc. GraphenX is a polar and functionalized material bearing several types of oxygen groups and is available in polar solvents (Water, NMP, DMF and Ethanol).
Our GraphenX products are comprised of single layers of graphene oxide. It is a product of oxidation of graphite through a modified Hummers’ method. In contrast to commercially available graphene oxide sheets which possess lateral size generally less than 5μm, GraphenX are monolayers of oxidized graphene with outstandingly high lateral size (up to 0.1mm), rendering these products as an excellent candidate for diverse applications such as electronics, composite materials, energy and etc. GraphenX is a polar and functionalized material bearing several types of oxygen groups and is available in polar solvents (Water, NMP, DMF and Ethanol).
Biological and Medical Applications of Graphene NanoparticlesAI Publications
Graphene which is one of the latest additions to nanocarbon family has peculiar band structure, extraordinary thermal and electronic conductance and room temperature quantum Hall effect. It is used in for various applications in diverse fields ranging from catalysis to electronics. In addition to being components in electronic devices, GO have been used in nanocomposite materials, polymer composite materials, energy storage, biomedical applications, catalysis and as a surfactant with some overlaps between these fields Graphene oxide is a unique material that can be viewed as a single monomolecular layer of graphite with various oxygen containing functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups.
Deposition and Characterization of Sisal Fiber Composite Prepare By Iron Oxid...IJERA Editor
Iron oxide synthesized through sintering route. The present research work deals with ferrite composite prepared using chemical reactions. Ferric nitrates and ammonium chloride doped with sisal fiber has been prepared. The comparative studies of ferric oxide were examined through few characterizations. The structural behavior of iron oxide was studied in XRD, FT/IR, TEM and SEM. This behavior showed ferrite nature of the sample.
Since the Nobel prize for Physics was awarded to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”, the eyes of the scientific world have been focused on this so-called miracle material.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Biological and Medical Applications of Graphene NanoparticlesAI Publications
Graphene which is one of the latest additions to nanocarbon family has peculiar band structure, extraordinary thermal and electronic conductance and room temperature quantum Hall effect. It is used in for various applications in diverse fields ranging from catalysis to electronics. In addition to being components in electronic devices, GO have been used in nanocomposite materials, polymer composite materials, energy storage, biomedical applications, catalysis and as a surfactant with some overlaps between these fields Graphene oxide is a unique material that can be viewed as a single monomolecular layer of graphite with various oxygen containing functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups.
Deposition and Characterization of Sisal Fiber Composite Prepare By Iron Oxid...IJERA Editor
Iron oxide synthesized through sintering route. The present research work deals with ferrite composite prepared using chemical reactions. Ferric nitrates and ammonium chloride doped with sisal fiber has been prepared. The comparative studies of ferric oxide were examined through few characterizations. The structural behavior of iron oxide was studied in XRD, FT/IR, TEM and SEM. This behavior showed ferrite nature of the sample.
Since the Nobel prize for Physics was awarded to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”, the eyes of the scientific world have been focused on this so-called miracle material.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Presentation from the New Mexico Regional Energy Storage and Grid Integration Workshop: Storage at the Threshold - Beyond Lithium-ion Batteries, presented by George Crabtree, Director, JCESR, Argonne National Laboratory, August 23-24.
Lithium Battery Fires for the general publicGlyn Chadwick
This slide stack is a version of an online course looking at Lithium Battery fires. It looks at where you can find Lithium Batteries, why they catch fire, how to fight fires and how to prevent them.
This presentation was prepared for the 2015 Benchmark Minerals Intelligence Battery Raw Materials | Supply Chain 20/20 World Tour and was presented in NYC and Toronto by CEO Paul Gorman.
Part 1 of the tutorial on the Lithium Battery Explorer provides an overview of Li-ion battery technology and the properties that are relevant to battery researchers.
Interested viewers should refer to the following publications for more details:
1) Review: G. Ceder, G. Hautier, A. Jain, S. P. Ong. Recharging lithium battery research with first-principles methods. MRS Bulletin, 2011, 36, 185--191.
2) Computational Electrode Assessment: G. Hautier, A. Jain, S. P. Ong, B. Kang, C. Moore, R. Doe, and G. Ceder. Phosphates as Lithium-Ion Battery Cathodes: An Evaluation Based on High-Throughput ab Initio Calculations. Chemistry of Materials, 2011, 23(15), 3495-3508.
3) Predicting Battery Safety: S. P. Ong, A. Jain, G. Hautier, B. Kang, & G. Ceder. Thermal stabilities of delithiated olivine MPO4 (M=Fe, Mn) cathodes investigated using first principles calculations. Electrochemistry Communications, 2010, 12(3), 427--430.
A lithium-ion battery (sometimes Li-ion battery or LIB) is a member of a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell.
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries - Cr...CrimsonPublishersRDMS
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries by Christian M Julien* in Crimson Publishers: Peer Reviewed Material Science Journals
Vapor growth of binary and ternary phosphorusbased semiconductors into TiO2 n...Pawan Kumar
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with
the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12)
were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing
vapor phase reaction deposition, the cavities of 100 mm long TiO2 nanotubes were infiltrated;
approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive
characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman
spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the
substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water
splitting performance compared to pristine materials and were found to be more active at higher
wavelengths. SnIP@TiO2 emerged to be the most active among the polyphosphide@TiO2 materials. The
improved photocatalytic performance might be due to Fermi level re-alignment and a lower charge
transfer resistance which facilitated better charge separation from inorganic phosphides to TiO2.
Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@Si...Pawan Kumar
An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4
as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid
support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized
by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for
the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a
reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a
methanol yield of 2570.78 μmol per g cat after 48 h.
Vapor growth of binary and ternary phosphorus-based semiconductors into TiO 2...Pawan Kumar
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12) were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing vapor phase reaction deposition, the cavities of 100 μm long TiO2 nanotubes were infiltrated; approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water splitting performance compared to pristine materials and were found to be more active at higher wavelengths. SnIP …
Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@Si...Pawan Kumar
An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4
as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid
support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized
by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for
the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a
reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a
methanol yield of 2570.78 μmol per g cat after 48 h.
Application of Fe3O4 Sphere Doped with Zn for Enhanced Sonocatalytic Removal ...ijtsrd
Fe3O4 sphere doped Zn were successfully prepared by the simple one pot solvothermal method. Morphology and structure of the as synthesised products was checked through the XRD, SEM, HRTEM techniques. The Fe3¬O4 hollowsphere doped showed the high photocatalytic activity for degradation of hexavalent chromium under visible light irradiation. The effects of reaction conditions such as initial pH, photocatalyst dosage and hexavalent chromium contratentation were also studied systematically. The stability of the catalsyts and and possible catalytic mechanism was also proposed. The results indicate that Fe3O4 sphere doped Zn can be promising catalyst for photo reduction of hexavalent chromium. Xuan Sang Nguyen "Application of Fe3O4 Sphere Doped with Zn for Enhanced Sonocatalytic Removal of Cr (VI) From Aqueous Solutions" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-1 , December 2021, URL: https://www.ijtsrd.com/papers/ijtsrd47862.pdf Paper URL: https://www.ijtsrd.com/medicine/other/47862/application-of-fe3o4-sphere-doped-with-zn-for-enhanced-sonocatalytic-removal-of-cr-vi-from-aqueous-solutions/xuan-sang-nguyen
Using triple-layer remote phosphor structures LaVO4:Eu3+ and ZnS:Cu,Sn to imp...TELKOMNIKA JOURNAL
This research paper investigates the novel triple remote phosphor layer for improving the remote phosphor’s angular chroma uniformity (ACU) of down-light lamps by using remote micro-patterned phosphor layers (RMPP). In addition, introducing the triple-layer (TL) RMPP is introduced to offer the potential approach to this objective. This analysis also measures the optical efficiency of the layers and the angle distribution of angular correlated color temperature (ACCT). Drawing a comparison between the traditional
dual-layer (DL) RMPP and the proposed TL is furthermore critical to this study. According to the findings, the triple-layer phosphor configuration can achieve greater hue consistency while having a correlating colour temperature (CCT) variance merely measured at 441 K. Results in the single RMPP layer are 1390 K of the remote phosphor (RP) sheet setting and
556 K for the ACCT deviation. The recreation employing finite-difference
time-domain (FDTD) as well as the approach of ray-tracing ensures an increase in angular color uniformity (ACU). The structure of DL and TL RMPPs results in a 6.68 % and 4.69 % gain in luminous efficiency, respectively, with the standard RMPP layer at a currently driving of 350 mA. The micro-patterned layer’s scattering characteristic and mixing effect may account for the increased ACU and luminous efficiency.
Crystal Structure, Topological and Hirshfeld Surface Analysis of a Zn(II) Zwi...Awad Albalwi
Abstract: A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2
) (1) has been synthesized by using
a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene)
amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy,
TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II)
complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry
(τ = 0.68).
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.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
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.
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.
Richard's entangled aventures in wonderlandRichard Gill
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.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
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/NASA’s 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 Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
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 .
2. limiting factor of rf magnetron sputtering from Li3PO4 ceramic target is
the low deposition rate (typically 2 nm/min) [20] and a non-uniform
erosion which eventually leads to non stoichiometry of the multi-
elemental target. Lee et al. [21] for rf sputtered LiPON films and Kim et al.
[22]for plasma assisted PVD of LiPONfilmshave reported higher growth
rates with an ionic conductivity in the range of 10−7
–10−9
Scm−1
.
Typically lithium phosphate targets are prepared by a series of
steps which includes calcinations of Li3PO4 powder, binder addition,
drying, sieving and ball milling followed by hot/cold press to increase
the density of the target. This disc has to be sintered for long hours to
complete the target making process. But after few depositions, β
Li3PO4 transforms to polymorphic γ Li3PO4 due to temperature
increase in the target which finally leads to cracking of the sintered
targets [23]. Considering the material loss associated and cost of
production of ceramic sintered targets, sputtering from powder target
is a straight forward and cost effective technique. This avoids cracking
of brittle targets due to low thermal conductivity. Sputtering from
powder target has been reported for multi-component films such as
YBCO, CrB–MoSx and CrB–TiC–MoSx with good repeatability [24,25].
In the present study we have combined the merits of rf sputter
deposition and a cost effective powder compact Li3PO4 target in N2
plasma. The goals of this study are to,
i. Explain the synthesis of LiPON films in N2 plasma from a
powder compact Li3PO4 target with a high deposition rate.
ii. Characterize the properties of resulting films in terms of
structure, surface morphology, N2 incorporation by elemental
composition study and Li+
-ion conductivity.
iii. Optimize the deposition conditions in terms of rf power and N2
flow during deposition.
2. Experimental details
Stoichiometric Li3PO4 powder targets were made by filling Li3PO4
powder (99.99% Sigma Aldrich ) in a 3 inch diameter Cu disk with a
trench of 3 mm depth and was packed tightly by pressing with a flat
metal plate. This powder target was fixed on to rf magnetron in a
sputter-up configuration. The schematic representation of the
deposition system with powder target arrangement is shown in Fig. 1.
Fig. 1. Schematic illustration of magnetron sputtering system using Li3PO4 powder
target for LiPON deposition.
Fig. 2. Schematic layout of metal–insulator–metal (MIM) structure of Pt/LiPON/Al for
impedance measurement.
Fig. 3. XRD patterns of pure Li3PO4 powder target and LiPON film deposited.
(Deposition conditions: rf power density of 3 Wcm−2
, N2 flow of 30 sccm).
Fig. 4. (a) SEM image of LiPON film surface on Pt coated Si substrate and (b) cross-
section of Pt/LiPON/Al (MIM) structure. (Deposition conditions are, Rf power density of
3 Wcm−2
, N2 flow of 30 sccm.)
3402 C.S. Nimisha et al. / Thin Solid Films 519 (2011) 3401–3406
3. Pre-cleaned platinum deposited silicon substrates (Silicon Valley
Inc.USA) were held at a distance of 4 cm away from the target. The
substrate holder was provided with a to and fro movement above the
target for homogeneous deposition of the film over the substrate. A
base vacuum of 1×10−6
mbar was obtained with a turbo molecular
pump backed by a rotary pump. The powder compact target was pre-
sputtered for an hour to remove any hydrocarbons present and also to
sinter the top layers of target locally. Substrate temperature was not
controlled during deposition, but was observed to rise up to 110 °C
towards the end of deposition due to plasma heating. The deposition
time of 40 min was kept constant for all the depositions used in this
Fig. 5. Impedance spectra of LiPON thin films deposited from powder target at different rf power densities (a) 1.7 Wcm− 2
(b) 2.2 Wcm−2
, (c) 2.6 Wcm−2
, (d) 3 Wcm−2
from Pt/
LiPON/Al sandwich structure.
Fig. 6. Arrhenius plot of ionic conductivity of LiPON thin film vs. temperature.
(Deposition conditions: rf power density of 3 Wcm−2
, nitrogen flow of 30 sccm).
Fig. 7. XPS survey spectra of LiPON film and Li3PO4 powder used as target. (Deposition
conditions are, rf power density of 3 Wcm−2
, N2 flow of 30 sccm).
3403C.S. Nimisha et al. / Thin Solid Films 519 (2011) 3401–3406
4. study. Rf power density was varied from 1.7 Wcm−2
to 3 Wcm−2
and
N2 flow from 10 to 40 sccm in order to optimize the processing
conditions.
The crystal structure of Li3PO4 powder and films was characterized
by X-ray diffraction (XRD) using Bruker D8 Advance (Cu-Kα radiation,
λ=1.5405 A0
). A SIRION 200 field emission scanning electron
microscope (FESEM) was employed to investigate the surface
morphology and cross sectional microstructure of LiPON films. All
the samples were coated with a thin Pd/Au layer to reduce surface
charging effects.
X-ray photoelectron spectroscopy (XPS) analysis was performed
with SPECS GmbH spectrometer (Phoibos 100 MCD Energy Analyzer)
using MgKα radiation (1253.6 eV). The residual pressure inside the
analysis chamber was in 10−10
mbar range. The spectrometer was
calibrated using photoemission lines of Ag (Ag 3d3/2=367 eV with
reference to Fermi level). Peaks were recorded with constant pass
energy of 40 eV. Because of surface charge induced peak shifts, C 1s at
284.6 eV was taken as a reference energy position to correct the shift.
The N 1s peaks were resolved using a peak synthesis program in
which a non-linear background was assumed. The synthetic peaks
were defined with a combination of Gaussian and Lorentzian
distributions with a fixed FWHM of 1.8 eV.
The LiPON film thickness was determined from Dektak 150 stylus
profilometer. Ionic conductivity of the films was obtained from the
AC-impedance measurement of Pt/LiPON/Al sandwich structures
(Fig. 2) fabricated on Pt coated silicon substrates with a LiPON
thickness of 1 μm and Al top layer deposited by thermal evaporation
to an area of 2×2 mm. The test cells showed an open circuit voltage of
1.6 V. The AC-impedance measurements were performed at room
temperature and at higher temperature (27 °C to 130 °C) using a Bio-
Logic SA potentiostat/Galvanostat (model: VPM3) at frequencies from
1 Hz to 100 KHz.
3. Results and discussion
X-ray diffraction patterns of pure Li3PO4 powder and LiPON film
deposited on silicon wafer are shown in Fig. 3. While Li3PO4 powder
has various crystalline phases, LiPON film did not exhibit any peaks,
indicating amorphous nature of the film. This is advantageous for
battery applications since the ionic conductivity of amorphous films is
generally more isotropic and higher than that of single crystal or
textured polycrystalline films [26].
Fig. 4(a) shows the surface micrograph of as deposited LiPON film
on Pt coated silicon and the cross-sectional view of Pt/LiPON/Al
sandwich structure in Fig. 4(b). The as deposited LiPON film is smooth
without any cracks or pin holes on the surface. Also at the interface it
makes a clean contact with the top and bottom metal layers,
minimizing interfacial resistance between the layers.
Li+
-ion conductivity of LiPON films was measured by electro-
chemical impedance spectroscopy. Complex impedance of each of the
test pads was measured in 1–105
Hz frequency range at room
temperature. The impedance obtained is a characteristic of a single-
phase ionic conductor with blocking electrode configuration. The
ionic conductivity was calculated from the electrolyte resistance Rel
(which is the real part of impedance ZRe value at selected frequency in
which −Zim goes through a local minimum-Yu method) using the
relation,
σ = 1= Rel × d = A
where d is the thickness and A is the surface area of contact of LiPON
thin films [27]. There have been contradictory reports on the effect of rf
power density on ionic conductivity of LiPON film. Earlier Choi et al.
[28] reported that ionic conductivity of sputter deposited LiPON films
was inversely proportional to rf power density, whereas, studies by
Roh et al. supported a directly proportional relation of ionic
conductivity with rf power density [29]. Our experiments showed an
increased ionic conductivity with increase in rf power density in
conformity with the study of Roh et al. The bode plot representation of
ionic conductivity obtained from LiPON films deposited with different
rf powers is shown in Fig. 5(a–d). It can be seen that as the rf power
density is increased from 1.7 Wcm−2
to 3 Wcm−2
, there is an increase
in the ionic conductivity from 2.3×10−9
Scm−1
to 1.1×10−6
Scm−1
.
According to linear fit of Arrhenius equation, impedance analysis
showed an increased ionic conductivity with increase in measurement
temperature (Fig. 6). The activation energy Ea of LiPON has been
calculated using the equation,
ln σTð Þ = ln σ0Tð Þ−Ea = kT
where Ea is the activation energy, σ is ionic conductivity, T is
temperature in Kelvin and k is Boltzmann constant. Activation energy
was found to be 0.44 eV for the LiPON film deposited at optimized
conditions.
In some of the reported studies on LiPON thin films, the rate of
deposition was very low from the ceramic target and hence long hours
of deposition were employed [20,30]. But we have observed that films
of 1.2 μm thick can be deposited from powder target of Li3PO4 in N2
plasma with a deposition time of 40 min. Here the rate of deposition is
around 30 nm/min, which is 15 times higher than the sputtering rate
from ceramic Li3PO4 target. In order to remove an atom from a target
surface, energy greater than surface binding energy (Esurf) has to be
supplied. Since for the powder target, atoms are loosely confined to
surrounding atoms, the energy required to remove it from the lattice
Fig. 8. (a) Core level spectra of P 2p region showing the shift in binding energy (B.E.) of
P 2p for film and Li3PO4 powder used as target, (b) C 1s region of LiPON film and Li3PO4
powder.
3404 C.S. Nimisha et al. / Thin Solid Films 519 (2011) 3401–3406
5. site is less compared with sintered target, which is relatively tight
packed. Thus, the higher deposition rate obtained from the powder
target compared to a ceramic target can be due to less binding energy
associated with the powder target. Also the microscopic unevenness
of top surface layer leads to higher effective surface area of powder
particles which contributes to high deposition rates.
To investigate the chemical nature of deposited films, XPS analysis
of LiPON thin films deposited from powder target was done to provide
information about elemental bonding environment. Estimated error
in the calculated chemical composition can be around 10% for multi-
elemental compounds [31]. Survey scans of Li3PO4 powder and LiPON
films done from 1100 to 10 eV clearly depict the incorporation of
Fig. 9. N 1s XPS spectra with component analysis showing triply coordinated nitrogen as Nt and doubly coordinated nitrogen as Nd of LiPON films deposited with 4 different rf
powder densities, (a) 1.7 Wcm−2
, (b) 2.2 Wcm−2
, (c) 2.6 Wcm−2
, (d) 3 Wcm− 2
.The solid symbols represent the raw data and smooth curve represents the fitted data.
Fig. 10. Ionic conductivity and Nt/Nd ratio of LiPON thin films as a function of rf power
density.
Fig. 11. Ionic conductivity and Nt/Nd ratio of LiPON thin films as a function of nitrogen
flow.
3405C.S. Nimisha et al. / Thin Solid Films 519 (2011) 3401–3406
6. nitrogen in to LiPON film, which was otherwise absent in powder
sample (Fig. 7).
Studies with XPS showed a P 2p peak shift of Li3PO4 from 134.5 to
132.8 eV for LiPON films due to nitrogen incorporation [32]. This
reduction in binding energy is attributed to the replacement of P–O
bonds by P–N bonds which change the charge distribution around
phosphorus in thin films. Core level spectra of P 2p for both film and
powder samples are shown in Fig. 8(a) for comparison. Fig. 8(b)
shows the corresponding C 1s peaks from both Li3PO4 powder and
LiPON film. Also the study of amorphous phosphorous nitrides by
Veprek et al. suggested nitrogen incorporation as doubly (–N=) and
triply coordinated (–N≤) state [33]. Our studies on LiPON films,
revealed nitrogen incorporation in to Li3PO4 as both doubly
coordinated ‘Nd’ (peak at, 399.4 eV), or triply coordinated ‘Nt’, (peak
at, 400.8 eV) manner. Resolving N 1s spectrum of LiPON films
deposited with different rf power densities, into two components
and measuring the area of Nt and Nd gives a quantitative measure of
each. Fig. 9(a–d) shows N 1s spectrum and its component analysis for
the films deposited with different rf power densities of 1.7, 2.2, 2.6
and 3 Wcm−2
. A clear trend on increase in Nt is observed with
increase in rf power.
The effect of increased Nt/Nd ratio on ionic conductivity of LiPON film
with the increase in rf power density is plotted in Fig. 10. Due to the
higher ionic radius of N3−
compared with O2−
, the nitrogen substitution
in LiPON film for oxygen in Li3PO4 induces structural distortions, which
in fact improves the ionic conductivity and stability of LiPON. The
reduction in electrostatic energy, once the P–O bond is replaced by a
more covalent P–N bond, lowers the activation energy of Li±
mobility in
the defect lattice. It was suggested that more structural distortion
induced by cross linked Nt than Nd in the LiPON films, consequently
improving ionic conductivity with increased triply coordinated nitrogen
Nt [29,34]. For an rf power density of 1.7 Wcm−2
, Nt/Nd ratio obtained
was 0.27 with an ionic conductivity of 2.3×10−9
Scm−1
. But as the rf
power density increased to 3 Wcm−2
, Nt/Nd ratio improved to 1.42 and
the ionic conductivity also increased to 1.1×10−6
Scm−1
. However
increase of rf power density beyond 3 Wcm−2
was difficult as the
powder particles of the target begin to splash to growing thin film
surface.
Other than the rf power density, nitrogen flow rate is an important
process parameter that governs ionic conductivity of LiPON films [18].
We have selected four different flow rates of 10, 20, 30 and 40 sccm of
nitrogen to fine tune the conductivity obtained with rf power density of
3 Wcm−2
. The dependence of ionic conductivity on N2 flow rate and Nt /
Nd ratio obtained from XPS analysis is shown in Fig. 11. Initially ionic
conductivity increases from 7.2×10−9
Scm−1
to 1.1×10−6
Scm−1
for
a flow rate increase of 10 to 30 sccm. But for 40 sccm of N2, the
deposition rate itself reduces due to increased scattering of sputtered
species and conductivity reduces to 4.7×10−7
Scm−1
. With the
increase in the nitrogen flow, the incorporation of nitrogen into the
lithium phosphate matrix in the film as well as the source also increases.
Further addition of nitrogen into the source results in a reduction in the
sputtering rate. It was observed that the deposition rate was increased
from15 nm/min to 30 nm/min as the nitrogen flow increased from 10 to
30 sccm.At a flow rate of 40 sccm, the deposition rate reduced to 20 nm/
min and this effect was seen in the incorporation of nitrogen in the film.
It has been also confirmed by XPS studies that a film deposited with
40 sccm of nitrogen flow has lesser Nt/Nd ratio. The maximum obtained
ionic conductivity from this study is 1.1×10−6
Scm−1
, which is low
compared to the best reported ionic conductivity (3.3×10−6
Scm−1
of
LiPON films by Hu et al. [20]). However, LiPON films with an ionic
conductivity of 4.5×10−7
Scm−1
has already been demonstrated as
solid electrolyte of a LiCoO2/LiPON/Li TFB with a discharge capacity of
59 μAh cm−2
μm−1
and good capacity retention [35].
4. Conclusions
In this study we have shown that, sputtering from powder target
can be useful for certain compounds like Li3PO4 in which breaking of
ceramic target and material loss are severe problems. The ionic
conductivity of LiPON films formed was in relative good agreement
with previously reported values with a higher deposition rate. The
effects of rf power change and N2 flow during deposition are studied
in detail. It is seen that with increase in rf power density, ionic
conductivity is increased and for increased nitrogen flow, there is an
increased ionic conductivity for 10 to 30 sccm but reduces for higher
N2 flow of 40 sccm. Amorphous nature of the films during deposition
process has been ensured and verified through XRD. Incorporation of
triply coordinated nitrogen enhances the ionic conductivity which has
been confirmed by XPS and AC impedance analysis. A maximum ionic
conductivity of 1.1×10−6
Scm−1
was obtained for an Nt/Nd ratio of
1.42 for 3 Wcm−2
and N2 flow of 30 sccm.
Acknowledgement
The authors acknowledge DRDO, Govt. of India for funding this
work.
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