Gives an idea about Nanoparticle's background and introduction to Nanoworld. Engineering the shape and thus surface structure of Pt nanocrystals is an effective strategy for optimizing their catalytic activities toward various reactions. However, different protocols are typically used to produce Pt nanocrystals with distinctive shapes, making it difficult to directly compare their catalytic activities owing to the complication of surface contamination. Here we demonstrate that Pt nanocrystals with a variety of shapes, including those enclosed with low- or high-index facets, can be synthesized using the same protocol by simply adjusting the concentration of reducing agent and/or the reaction time.
Doped strontium vanadate: Computational design of a stable, low work function...Ryan Jacobs
Presentation at the IEEE-IVEC conference in 2016 on computational modeling of perovskite work function physics and discovery of low work function materials
Talk by Dane Morgan at the TMS Annual Meeting, March 18, 2015, in Orlando Florida. Topic is Structure and Thermokinetics of Y-Ti-O Precipitates in Nanostructured Ferritic Alloys.
Origin of the Size-Dependent Fluorescence Blueshift in [n]Cycloparaphenylenes Stephan Irle
We present quantum chemical electronic structure calculations to investigate the nature of the low-lying excited states of [n]cycloparaphenylenes ([n]CPPs) and the role of static and dynamic geometrical distortions in the bright states. The lowest-energy bright states involve single-electron excitations from S0 ground state to S2 and S3 states, which are at the Franck-Condon geometry the two components of a twofold degenerate 1E state. They couple to a twofold degenerate e vibration which induces Jahn-Teller (JT) deformation of the CPP geometry from circular to oval shape. Non-radiative decay from the S2/S3 states to the ground S0 and first excited, dark S1 states is suppressed due to symmetry rules. The emission spectral features in CPPs with large number of phenylene units n can therefore largely be attributed to the E ⊗ e JT system associated with S2 and S3. However, absorption and emission energies computed at the respective S0 and S2/S3 minimum energy geometries are found to be nearly identical, independent of the molecular size n in the CPP molecules. In contrast, molecular dynamics simulations performed on the excited state potential surfaces are able to explain the experimentally observed fluorescence blueshift of the strongest emission peaks with increasing molecular size. This unusual feature turns out to be a consequence of large vibrational amplitudes in small [n]CPPs, causing greater Stokes shifts, while large [n]CPPs are more rigid and therefore feature smaller Stokes shifts (“dynamic blueshift”). For the same reasons, symmetry rules are violated to a greater extent in small [n]CPPs, and it is expected that in their case a “static blueshift” due to emission from S1 contributes in the fluorescence spectra.
Plenary lecture given by Prof. Hajo Freund (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany) on September 11, 2017 in Gramado (Brazil) during the XVI B-MRS Meeting.
Doped strontium vanadate: Computational design of a stable, low work function...Ryan Jacobs
Presentation at the IEEE-IVEC conference in 2016 on computational modeling of perovskite work function physics and discovery of low work function materials
Talk by Dane Morgan at the TMS Annual Meeting, March 18, 2015, in Orlando Florida. Topic is Structure and Thermokinetics of Y-Ti-O Precipitates in Nanostructured Ferritic Alloys.
Origin of the Size-Dependent Fluorescence Blueshift in [n]Cycloparaphenylenes Stephan Irle
We present quantum chemical electronic structure calculations to investigate the nature of the low-lying excited states of [n]cycloparaphenylenes ([n]CPPs) and the role of static and dynamic geometrical distortions in the bright states. The lowest-energy bright states involve single-electron excitations from S0 ground state to S2 and S3 states, which are at the Franck-Condon geometry the two components of a twofold degenerate 1E state. They couple to a twofold degenerate e vibration which induces Jahn-Teller (JT) deformation of the CPP geometry from circular to oval shape. Non-radiative decay from the S2/S3 states to the ground S0 and first excited, dark S1 states is suppressed due to symmetry rules. The emission spectral features in CPPs with large number of phenylene units n can therefore largely be attributed to the E ⊗ e JT system associated with S2 and S3. However, absorption and emission energies computed at the respective S0 and S2/S3 minimum energy geometries are found to be nearly identical, independent of the molecular size n in the CPP molecules. In contrast, molecular dynamics simulations performed on the excited state potential surfaces are able to explain the experimentally observed fluorescence blueshift of the strongest emission peaks with increasing molecular size. This unusual feature turns out to be a consequence of large vibrational amplitudes in small [n]CPPs, causing greater Stokes shifts, while large [n]CPPs are more rigid and therefore feature smaller Stokes shifts (“dynamic blueshift”). For the same reasons, symmetry rules are violated to a greater extent in small [n]CPPs, and it is expected that in their case a “static blueshift” due to emission from S1 contributes in the fluorescence spectra.
Plenary lecture given by Prof. Hajo Freund (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany) on September 11, 2017 in Gramado (Brazil) during the XVI B-MRS Meeting.
Multiprocess passive diffusion driven nano ion filter and brownian motion bat...Michael Changaris
Multiple new developments in physical principals allow for amplification of energy storage through passive and chemically driven process.
Membrane ion selectivity can allow for passive diffusion driven energy storage.
Light and heat can increase rate of Brownian motion enhancing the diffusion gradient and driving ion charge independently (e.g. heat differential in lightning production).
Graphene can organize in a single sheet possibly allowing for more effective harnessing of the ratchet that can drive browning motion into mechanical action.
Ion pumps driven by Nano properties can create ion specific transport driving energy storage and maintaining energy with slower decay.
Chemical cascades if appropriately directed can create a stable far from equilibrium system in which the byproduct of one reaction becomes the catalyst for the next step.
With sufficient complexity and properties of phase shift these cascades can drive each other through interacting oscillatory patterns for the life of the battery and time for needed for energy storage.
Computationally Driven Characterization of Magnetism, Adsorption, and Reactiv...Joshua Borycz
Metal organic frameworks (MOFs) are a class of nanoporous materials that are com- posed of metal-containing nodes connected by organic linkers. The study of MOFs has grown in importance due to the wide range of possible node and linker combinations, which allow tailoring towards specific applications. This work demonstrates that the- ory can complement experiment in a way that advances the chemical understanding of MOFs. This thesis contains the results of several investigations on three different areas of MOF research: 1) magnetism, 2) CO2 adsorption, and 3) catalysis.
Influence of concentration on the structural, optical and electrical properti...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
SWCNT Growth from Chiral and Achiral Carbon Nanorings: Prediction of Chiralit...Stephan Irle
Catalyst-free, chirality-controlled growth of chiral and achiral single-walled carbon nanotubes (SWCNTs) from organic precursors is demonstrated using quantum chemical simulations [1]. Growth of (4,3), (6,5), (6,1), (10,1), (6,6) and (8,0) SWCNTs was induced by ethynyl radical (C2H) addition to organic precursors. These simulations show a strong dependence of the SWCNT growth rate on the chiral angle, θ. The SWCNT diameter however does not influence the SWCNT growth rate under these conditions. This agreement with a previously proposed screw-dislocation-like model of transition metal-catalyzed SWCNT growth rates [2] indicates that the SWCNT growth rate is an intrinsic property of the SWCNT edge itself. Conversely, we predict that the rate of local SWCNT growth via Diels-Alder cycloaddition of C2H2 is strongly influenced by the diameter of the SWCNT. We therefore predict the existence of a maximum local growth rate for an optimum diameter/chirality combination at a given C2H/C2H2 ratio. We also find that the ability of a SWCNT to avoid defect formation during growth is an intrinsic quality of the SWCNT edge.
References:
[1] Li, H.-B.; Page, A. J.; Irle, S.; Morokuma, K. J. Am. Chem. Soc. 2012, 134, 15887-15896.
[2] Ding, F.; Harutyunyan, A. R.; Yakobson, B. I. Proc. Natl. Acad. Sci. 2009, 106, 2506-2509.
Strain effect in the crystal structure causes enhanced catalytic effect which is very beneficial for different process. In this Presentation it is discussed how the strain is generated and what is its effect.
degradation of pollution and photocatalysisPraveen Vaidya
The presentation deals with the use of conduction of photocatalytic reaction using the transition metal doped transparent semiconducting thinfilms. The precursor to film is prepared by the SILAR method, which is a chemical method.
2018-11-26 Investigation of the band structure of quantum wells based on gapl...LeonidBovkun
The present PhD thesis primarily aims at filling some of existing gaps in our understanding of the electronic band structure in 2D and quasi-2D heterostructures based on HgTe/HgCdTe and InAs/InSb materials, which both may be tuned into topologically insulating phase using particular structural parameter. To explore their properties, the primal experimental technique, infrared and THz magneto-spectroscopy operating in a broad of magnetic fields, is combined with complementary magneto-transport measurements. This combination of experimental methods allows us to get valuable insights into electronic states not only at the Fermi energy, but also in relatively broad vicinity.
Improving Crystallite Size and Orientation in Organic Semiconductor Thin Film...VestaZhelyaskova
We aim to develop a scalable, solution-based method for growing crystalline organic semiconductor thin films, which can be used in a variety of electronic charge transport, metal doping, and device integration studies. Using a polydimethylsiloxane (PDMS)-assisted deposition method for fullerenes, we grew polycrystalline C60 thin films on plain glass, between gold electrodes on glass, and on silicon substrates under a range of growth conditions. AFM characterization revealed that the films (1) were typically 200-300 nm thick, (2) were made up of crystallites extending up to 200 μm, and (3) had crystalline microstructures that vary with choice of solvent, temperature, and substrate pre-treatment. Films grown from carbon disulfide solutions covered larger areas than those grown out of o-dichlorobenzene—an interplay between the C60’s low solubility and the PDMS’s absorption of nonpolar solvents. Growth at lower temperatures resulted in uniformly aligned crystallites, which formed farther from the PDMS-substrate boundary. Growth along and between gold contacts resulted in nucleation of similarly aligned crystallites at the gold's edge. Here we discuss the growth kinetics of these films along with their electronic, structural, and spectroscopic characterizations.
*W. M. Keck Foundation
Multiprocess passive diffusion driven nano ion filter and brownian motion bat...Michael Changaris
Multiple new developments in physical principals allow for amplification of energy storage through passive and chemically driven process.
Membrane ion selectivity can allow for passive diffusion driven energy storage.
Light and heat can increase rate of Brownian motion enhancing the diffusion gradient and driving ion charge independently (e.g. heat differential in lightning production).
Graphene can organize in a single sheet possibly allowing for more effective harnessing of the ratchet that can drive browning motion into mechanical action.
Ion pumps driven by Nano properties can create ion specific transport driving energy storage and maintaining energy with slower decay.
Chemical cascades if appropriately directed can create a stable far from equilibrium system in which the byproduct of one reaction becomes the catalyst for the next step.
With sufficient complexity and properties of phase shift these cascades can drive each other through interacting oscillatory patterns for the life of the battery and time for needed for energy storage.
Computationally Driven Characterization of Magnetism, Adsorption, and Reactiv...Joshua Borycz
Metal organic frameworks (MOFs) are a class of nanoporous materials that are com- posed of metal-containing nodes connected by organic linkers. The study of MOFs has grown in importance due to the wide range of possible node and linker combinations, which allow tailoring towards specific applications. This work demonstrates that the- ory can complement experiment in a way that advances the chemical understanding of MOFs. This thesis contains the results of several investigations on three different areas of MOF research: 1) magnetism, 2) CO2 adsorption, and 3) catalysis.
Influence of concentration on the structural, optical and electrical properti...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
SWCNT Growth from Chiral and Achiral Carbon Nanorings: Prediction of Chiralit...Stephan Irle
Catalyst-free, chirality-controlled growth of chiral and achiral single-walled carbon nanotubes (SWCNTs) from organic precursors is demonstrated using quantum chemical simulations [1]. Growth of (4,3), (6,5), (6,1), (10,1), (6,6) and (8,0) SWCNTs was induced by ethynyl radical (C2H) addition to organic precursors. These simulations show a strong dependence of the SWCNT growth rate on the chiral angle, θ. The SWCNT diameter however does not influence the SWCNT growth rate under these conditions. This agreement with a previously proposed screw-dislocation-like model of transition metal-catalyzed SWCNT growth rates [2] indicates that the SWCNT growth rate is an intrinsic property of the SWCNT edge itself. Conversely, we predict that the rate of local SWCNT growth via Diels-Alder cycloaddition of C2H2 is strongly influenced by the diameter of the SWCNT. We therefore predict the existence of a maximum local growth rate for an optimum diameter/chirality combination at a given C2H/C2H2 ratio. We also find that the ability of a SWCNT to avoid defect formation during growth is an intrinsic quality of the SWCNT edge.
References:
[1] Li, H.-B.; Page, A. J.; Irle, S.; Morokuma, K. J. Am. Chem. Soc. 2012, 134, 15887-15896.
[2] Ding, F.; Harutyunyan, A. R.; Yakobson, B. I. Proc. Natl. Acad. Sci. 2009, 106, 2506-2509.
Strain effect in the crystal structure causes enhanced catalytic effect which is very beneficial for different process. In this Presentation it is discussed how the strain is generated and what is its effect.
degradation of pollution and photocatalysisPraveen Vaidya
The presentation deals with the use of conduction of photocatalytic reaction using the transition metal doped transparent semiconducting thinfilms. The precursor to film is prepared by the SILAR method, which is a chemical method.
2018-11-26 Investigation of the band structure of quantum wells based on gapl...LeonidBovkun
The present PhD thesis primarily aims at filling some of existing gaps in our understanding of the electronic band structure in 2D and quasi-2D heterostructures based on HgTe/HgCdTe and InAs/InSb materials, which both may be tuned into topologically insulating phase using particular structural parameter. To explore their properties, the primal experimental technique, infrared and THz magneto-spectroscopy operating in a broad of magnetic fields, is combined with complementary magneto-transport measurements. This combination of experimental methods allows us to get valuable insights into electronic states not only at the Fermi energy, but also in relatively broad vicinity.
Improving Crystallite Size and Orientation in Organic Semiconductor Thin Film...VestaZhelyaskova
We aim to develop a scalable, solution-based method for growing crystalline organic semiconductor thin films, which can be used in a variety of electronic charge transport, metal doping, and device integration studies. Using a polydimethylsiloxane (PDMS)-assisted deposition method for fullerenes, we grew polycrystalline C60 thin films on plain glass, between gold electrodes on glass, and on silicon substrates under a range of growth conditions. AFM characterization revealed that the films (1) were typically 200-300 nm thick, (2) were made up of crystallites extending up to 200 μm, and (3) had crystalline microstructures that vary with choice of solvent, temperature, and substrate pre-treatment. Films grown from carbon disulfide solutions covered larger areas than those grown out of o-dichlorobenzene—an interplay between the C60’s low solubility and the PDMS’s absorption of nonpolar solvents. Growth at lower temperatures resulted in uniformly aligned crystallites, which formed farther from the PDMS-substrate boundary. Growth along and between gold contacts resulted in nucleation of similarly aligned crystallites at the gold's edge. Here we discuss the growth kinetics of these films along with their electronic, structural, and spectroscopic characterizations.
*W. M. Keck Foundation
Nano porous membranes for water purification by shrinath ghadgeShrinath Ghadge
Continuous population growth and urbanization as well as rapid industrialization, causing huge contamination of potable water or underground water, has been a serious concern all over the world. Due to incompetency of conventional water purification technologies to deliver complete pollutants free water at an economical price, a high performance, cost-effective and environmentally acceptable separation system is an urgent need which should not only remove macro-, micro- and nano-pollutants but also desalinate water to a significant extent. In this milieu, nanotechnology based carbon nanotube (CNT) membranes have shown impressive breakthroughs towards water purification as compared to existing energy intensive water purification systems and thus, this technology has immense potential for large scale commercial water purification in a cost effective manner.
Bicrystalline Titania Photocatalyst for Reduction of CO2 to Solar FuelsA'Lester Allen
Degussa P25, a mixture of anatase and rutile crystal structures, is the most commonly used precursor to form the photoactive layer in solar cells; however, the photocatalytic activity of rutile is inferior to brookite. This presentation discusses the enhancement in photocatalytic activity of an antase brookite mixture.
Plenary lecture of the XIII SBPMat (Brazilian MRS) meeting, given on September 30th 2014 by Karl Leo, professor of optoelectronics at Dresden University of Technology (Germany) and director of the Solar and Photovoltaic Engineering Research Center at KAUST (Saudi Arabia).
IA Literature Review on Synthesis and Characterization of enamelled copper wi...Editor IJCATR
This paper discusses about the survey on the various magazines, conference papers and journals for understanding the
properties of enamelled copper wires mixed with nano fillers, fundamental methods for synthesis and characterization of carbon
nanotubes. From all these papers, it was noted that the research work carried out in an enamelled copper wires filled with nano fillers
has shown better results. It was also recorded that the research work was carried mostly with single metal catalysts and very little
amount of research work has been carried out on the synthesis of carbon nanotubes using bimetallic catalysts.
Similar to Synthesis of Pt Nanoparticles with different shapes using the same protocol to optimize their catalytic activity (20)
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.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
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.
ISI 2024: Application Form (Extended), Exam Date (Out), EligibilitySciAstra
The Indian Statistical Institute (ISI) has extended its application deadline for 2024 admissions to April 2. Known for its excellence in statistics and related fields, ISI offers a range of programs from Bachelor's to Junior Research Fellowships. The admission test is scheduled for May 12, 2024. Eligibility varies by program, generally requiring a background in Mathematics and English for undergraduate courses and specific degrees for postgraduate and research positions. Application fees are ₹1500 for male general category applicants and ₹1000 for females. Applications are open to Indian and OCI candidates.
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.
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.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
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.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
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.
Nutraceutical market, scope and growth: Herbal drug technology
Synthesis of Pt Nanoparticles with different shapes using the same protocol to optimize their catalytic activity
1. Synthesis of Pt nanocrystals with
different shapes using the same
protocol to optimize their catalytic
activity
Amol Nanduji Jaybhaye
2. Overview
• Background on nanoparticles
• Synthesis and experimentation
• Characterization
• Conclusion and future prospective
2
3. Background on Nanoparticle
• “Nanotechnology is the science of manipulating matter at nanoscale.”
• ‘Nano’ is a Greek word, means Dwarf
• 1nm = 10-9 m i.e. One billionth of a meter
• Every substance regardless of composition exhibits new properties
when the size is reduced to nanoscale.
3N.K. Tolochko NANOSCIENCE AND NANOTECHNOLOGIES - History Of Nanotechnology Encyclopedia of Life Support Systems (EOLSS), 2009, page no 50-60.
4. Things behave differently in Nano-World
• Carbon
Graphite (pencil lead) can be stronger than steel
and six time lighter
• Copper
Highly elastic metal at room temperature
Stretch 50 times its original length without breaking
• Gold
Shiny orange yellow Gold changes its color to
red, brownish black on reducing the size.
Benelmekki, M. Designing Hybrid Nanoparticles; Morgan & Claypool Publishers, 2015.
4
5. Top-down Approach
M. Designing Hybrid Nanoparticles; Morgan & Claypool Publishers, 2015, Chapter 2.Benelmekki, M. Designing Hybrid Nanoparticles; Morgan & Claypool Publishers, 2015, Chapter 2.
Chan,H.-K.;Kwok,P.C.L.ProductionMethodsforNanodrugParticlesUsingtheBottom-up
Bottom-up Approach
5
6. History of Nanotechnology
N.K. Tolochko NANOSCIENCE AND NANOTECHNOLOGIES - History Of Nanotechnology Encyclopedia of Life Support Systems (EOLSS), 2009, page no 50-60. 6
7. Proton Exchange Membrane (PEM) fuel cells
Very attractive for
transportation and
related fields
Clean energy source
in high power density
at low emission
Direct methanol fuel
cells (DMFCs)
Oxygen reduction
reaction (ORR)
Borup, R.; Meyers, J.; Pivovar, B.; Kim, Y. S.; Mukundan, R.; Garland, N.; Myers, D.; Wilson, M.; Garzon, F.; Wood, D.; et al. Scientific Aspects of Polymer Electrolyte Fuel Cell
Durability and Degradation. Chem. Rev. 2007, 107 (10), 3904–3951. 7
8. Oxygen Reduction Reaction (ORR)
• Important reaction in biological respiration, and in energy converting
systems such as fuel cells
• Pt is the most efficient electro-catalyst can accelerate sluggish kinetics that
occur at Cathode of PEM fuel cells
• Platinum (Pt)-
- High cost
- Low reserves in earth’s crust
8Borup, R.; Meyers, J.; Pivovar, B.; Kim, Y. S.; Mukundan, R.; Garland, N.; Myers, D.; Wilson, M.; Garzon, F.; Wood, D.; et al. Scientific Aspects of Polymer Electrolyte Fuel Cell
Durability and Degradation. Chem. Rev. 2007, 107 (10), 3904–3951.
9. Platinum (Pt) Nanoparticles
• Can mitigate Platinum issue in ORR
• Pt nanoparticles have enhanced catalytic activity compare to bulk
form Pt
• Catalytic activities depend on the type of facets exposed on
nanocrystal surface
Mazumder, V.; Lee, Y.; Sun, S. Recent Development of Active Nanoparticle Catalysts for Fuel Cell Reactions. Adv. Funct. Mater. 2010, 20 (8), 1224–1231. 9
10. Platinum (Pt) Nanoparticles (cont.)
• Low index facets :
have low specific surface energy
ex: {100} and {111}
• High index facets : enhanced catalytic activity
high densities of atomic steps, kinks, edges, and can thus
provide more active sites to break chemical bonds
Quan, Z.; Wang, Y.; Fang, J. High-Index Faceted Noble Metal Nanocrystals. Acc. Chem. Res. 2013, 46 (2), 191–202. 10
Hard to compare different facets / nanoparticles as surfaces covered
by different species due to use of different chemicals / protocols
11. What is the Author’s Purpose?
• Facile method for synthesis of Pt nanocrystals with diversified shapes
exposing Low- or High-index facets
• High index facets have more oxygen reduction reaction than low
index facets
Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
11
12. Experimental Procedure
• Sodium hexachloroplatinate(IV) hexahydrate (Na2PtCl6)
as a precursor
• Glucose as a reductant
• Hexadecyltrimethylammonium bromide (CTAB) as a surfactant
• Oleylamine (OAm) as a solvent, a surfactant, and
a co-reductant
12Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
13. Experimental Procedure (cont.)
Schematic illustration of two different growing pathways that lead to the generation of Pt nanocrystals with
distinctive shapes as a function of reaction time.
13Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
16. TEM (Transmission Electron Microscopy)
a) Initial burst of Nucleation for
the formation of Pt
seeds with sizes range 1-4nm
0.25 h
b) Seeds evolved into
Truncated cubes
opposite faces - 6.5 nm
1 h
16Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
c) Formation of Cuboctahedrons
opposite faces – 8.6 nm
2h
d)Truncated octahedrons
opposite faces – 12.9 nm
3h
17. TEM (Transmission Electron Microscopy)
(cont.)
e) Pt octahedrons with {111}
facets only
average edge length- 18.5 nm
4h
f) Larger Pt octahedrons
average edge length- 21.4 nm
5h
17Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
18. What we get from TEM (Transmission
Electron Microscopy) images?
Shape of Pt nanocrystals is highly depending on the reaction time.
Obtained 4 distinctive shapes or type of facets on the surface by
simply varying reaction time at a fixed glucose concentration.
18Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
19. TEM (Transmission Electron Microscopy)
a) Pt hollow crystals
Absence of glucose
Avg. size- 24.1 nm
b) Mixture of Pt octahedrons(21%)
truncated octahedrons(79%)
Concentration increased to 50mM
19Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
c) Different morphologies like
truncated cubes, cuboctahedrons,
rods, and tripods
Concentration increased to 133 mM
d) Pt concave cubes
apex to apex – 12.2 nm
High concentration- 167mM
20. TEM (Transmission Electron Microscopy)
(cont.)
e) Smaller concave cubes –
Broaden size distribution and other shapes
200 mM
f) Smaller concave cubes –
Broaden size distribution and other shapes
300 mM
20Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
21. What we get from TEM (Transmission
Electron Microscopy) images?
Shape of Pt nanocrystals is also depending on the
concentration of reductant i.e. Glucose
Obtained different shapes or type of facets on the surface
by simply varying glucose concentration.
21
22. TEM Images of Intermediate products at
different synthesis stages
a) Pt cubes- early stage
5.2 nm avg. edge length
1h
b) Pt cubes- edge length enclosed by {100} facets
increased to 8.1 nm, narrow size distribution
2h
22Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
23. TEM Images of Intermediate products at
different stages (cont.)
c) Cubes to Concave Cubes
Avg. apex to apex 10.1 nm
3h
d) Concave cubes-
Concavity increased- 12.2 nm
4h
23Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
24. HRTEM Images of Pt concave cube (t= 4h)
with FFT pattern
e) Average angle measured - 15.8o
f) Fast Fourier transform (FFT) pattern
24Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
25. HRTEM of edge region of Concave cube
g) edge region recorded from a concave cube
h) atomic model of the Pt{7 2 0} plane
-contains Multiple steps and
Subsets{410} and {310}
Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt
Nanocrystals with Different Shapes Using the Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction.
Materials Today 2018, 21 (8), 834–844.
25
Average angle measured - 15.8o
Theoretical value - 15.9o
26. cube octahedron concave cubecube octahedron concave cube
Surface effect of different shaped Pt
nanoparticles
26
Histogram of the comparative mass and specific activities at 0.90 V for the as-tested
catalysts.
Qian, J.; Shen, M.; Zhou, S.; Lee, C.-T.; Zhao, M.; Lyu, Z.; Hood, Z. D.; Vara, M.; Gilroy, K. D.; Wang, K.; et al. Synthesis of Pt Nanocrystals with Different Shapes Using the
Same Protocol to Optimize Their Catalytic Activity toward Oxygen Reduction. Materials Today 2018, 21 (8), 834–844.
The specific and mass activity depend strongly on the shape/facet, which
showed a trend in the order sequence of Pt{7 2 0} > Pt{1 1 1} > Pt{1 0 0}.
27. Conclusion
• Simple approach for shape/facet-controlled synthesis of Pt
nanocrystals by manipulating the reduction kinetics.
• Direct comparison of diverse nanoparticles activities towards ORR.
• High-index facets on Pt concave cubes gave more specific activity
compared to low-index facets, octahedrons and cubes.
27
28. Future Prospective
Good example of shape or facets-controlled
synthesis of Pt nanocrystals.
Shed light for development of future
nanocatalysts with optimal specific activities
toward different type of chemical reactions.
Significance of reduction kinetics in controlling
the structure evolution of other metal
nanocrystals.
28
Future Prospective
Good example of shape or facets-controlled
synthesis of Pt nanocrystals.
Shed light for development of future
nanocatalysts with optimal specific activities
toward different type of chemical reactions.
Significance of reduction kinetics in controlling
the structure evolution of other metal
nanocrystals.