This document describes a method for epithermal neutron activation analysis (ENAA) using a boron filter. A boron carbide filter with 500 mg/cm2 surface density was constructed and used to selectively filter out thermal neutrons while allowing higher energy epithermal neutrons to pass. Samples were irradiated both with and without the boron filter to determine boron activation ratios and improvement factors for interfering elements like sodium and scandium. The boron filter was shown to significantly reduce interferences from short-lived radionuclides like 24Na and 32P, allowing for shorter measurement times. Reference materials were also analyzed using both conventional INAA and the new ENAA method to demonstrate its accuracy and
Asymmetric Multipole Plasmon-Mediated Catalysis Shifts the Product Selectivit...Pawan Kumar
Cu/TiO2 is a well-known photocatalyst for the photocatalytic transformation of CO2 into methane. The formation of C2+ products such as ethane and ethanol rather than methane is more interesting due to their higher energy density and economic value, but the formation of C–C bonds is currently a major challenge in CO2 photoreduction. In this context, we report the dominant formation of a C2 product, namely, ethane, from the gas-phase photoreduction of CO2 using TiO2 nanotube arrays (TNTAs) decorated with large-sized (80–200 nm) Ag and Cu nanoparticles without the use of a sacrificial agent or hole scavenger. Isotope-labeled mass spectrometry was used to verify the origin and identity of the reaction products. Under 2 h AM1.5G 1-sun illumination, the total rate of hydrocarbon production (methane + ethane) was highest for AgCu-TNTA with a total CxH2x+2 rate of 23.88 μmol g–1 h–1. Under identical conditions, the CxH2x+2 production rates for Ag-TNTA and Cu-TNTA were 6.54 and 1.39 μmol g–1 h–1, respectively. The ethane selectivity was the highest for AgCu-TNTA with 60.7%, while the ethane selectivity was found to be 15.9 and 10% for the Ag-TNTA and Cu-TNTA, respectively. Adjacent adsorption sites in our photocatalyst develop an asymmetric charge distribution due to quadrupole resonances in large metal nanoparticles and multipole resonances in Ag–Cu heterodimers. Such an asymmetric charge distribution decreases adsorbate–adsorbate repulsion and facilitates C–C coupling of reaction intermediates, which otherwise occurs poorly in TNTAs decorated with small metal nanoparticles.
Vapor growth of binary and ternary phosphorus-based semiconductors into TiO2 ...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@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.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
The document describes the experimental methods used to synthesize and characterize hybrid fibrous red P@TiO2 and black P@TiO2 nanotube membrane materials for photoelectrocatalytic water splitting. TiO2 nanotube membranes were fabricated by anodization and then phosphorus allotropes were deposited via chemical vapor deposition. Characterization techniques included powder XRD, SEM/EDS, STEM/EDS, Raman spectroscopy, XPS, UPS, UV-Vis spectroscopy, KPFM, and gas chromatography to confirm the formation and properties of the hybrid materials. Structural analysis by XRD and Raman spectroscopy validated the incorporation of crystalline red and black phosphorus phases within the TiO2 nanotube membranes.
Harvesting Hot Holes in Plasmon-Coupled Ultrathin Photoanodes for High-Perfor...Pawan Kumar
The harvesting of hot carriers produced by plasmon decay to generate electricity or drive a chemical reaction enables the reduction of the thermalization losses associated with supra-band gap photons in semiconductor photoelectrochemical (PEC) cells. Through the broadband harvesting of light, hot-carrier PEC devices also produce a sensitizing effect in heterojunctions with wide-band gap metal oxide semiconductors possessing good photostability and catalytic activity but poor absorption of visible wavelength photons. There are several reports of hot electrons in Au injected over the Schottky barrier into crystalline TiO2 and subsequently utilized to drive a chemical reaction but very few reports of hot hole harvesting. In this work, we demonstrate the efficient harvesting of hot holes in Au nanoparticles (Au NPs) covered with a thin layer of amorphous TiO2 (a-TiO2). Under AM1.5G 1 sun illumination, photoanodes consisting of a single layer of ∼50 nm diameter Au NPs coated with a 10 nm shell of a-TiO2 (Au@a-TiO2) generated 2.5 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias, rising to 3.7 mA cm–2 in the presence of a hole scavenger (methanol). The quantum yield for hot-carrier-mediated photocurrent generation was estimated to be close to unity for high-energy photons (λ < 420 nm). Au@a-TiO2 photoelectrodes produced a small positive photocurrent of 0.1 mA cm–2 even at a bias of −0.6 V indicating extraction of hot holes even at a strong negative bias. These results together with density functional theory modeling and scanning Kelvin probe force microscope data indicate fast injection of hot holes from Au NPs into a-TiO2 and light harvesting performed near-exclusively by Au NPs. For comparison, Au NPs coated with a 10 nm shell of Al2O3 (Au@Al2O3) generated 0.02 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias. These results underscore the critical role played by a-TiO2 in the extraction of holes in Au@a-TiO2 photoanodes, which is not replicated by an ordinary dielectric shell. It is also demonstrated here that an ultrathin photoanode (<100 nm in maximum thickness) can efficiently drive sunlight-driven water splitting.
Flexible and Ultrasoft Inorganic 1D Semiconductor and Heterostructure Systems...Pawan Kumar
This document provides supporting information for a research article on flexible and ultra-soft inorganic semiconductor systems based on tin(II) iodide (SnIP). It includes details from quantum chemical calculations and experimental measurements that characterize the mechanical and structural properties of individual SnIP nanowires. Density functional theory calculations determine the phonon dispersion relations and Raman modes of SnIP under pressure. Experimental force-distance spectroscopy on suspended SnIP nanowires measures the Young's modulus, finding values around 190 GPa along the wire direction. High-pressure x-ray diffraction data and Rietveld refinement are used to calculate the bulk modulus of SnIP as 14.87 GPa, characterizing its compressibility.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
This document summarizes the preparation, characterization, and photocatalytic activity of nitrogen-doped titanium dioxide (TiO2). Yellow nitrogen-doped TiO2 was prepared through a sol-gel method using titanium isopropoxide and urea as precursors. Characterization with XRD, BET, TEM, XPS, and UV-Vis showed the materials were crystalline anatase TiO2 with nitrogen doping extending light absorption into the visible range. Photocatalytic testing demonstrated that nitrogen-doped TiO2 had higher activity for degrading the pesticide 2,4-D under visible light irradiation compared to undoped TiO2.
Asymmetric Multipole Plasmon-Mediated Catalysis Shifts the Product Selectivit...Pawan Kumar
Cu/TiO2 is a well-known photocatalyst for the photocatalytic transformation of CO2 into methane. The formation of C2+ products such as ethane and ethanol rather than methane is more interesting due to their higher energy density and economic value, but the formation of C–C bonds is currently a major challenge in CO2 photoreduction. In this context, we report the dominant formation of a C2 product, namely, ethane, from the gas-phase photoreduction of CO2 using TiO2 nanotube arrays (TNTAs) decorated with large-sized (80–200 nm) Ag and Cu nanoparticles without the use of a sacrificial agent or hole scavenger. Isotope-labeled mass spectrometry was used to verify the origin and identity of the reaction products. Under 2 h AM1.5G 1-sun illumination, the total rate of hydrocarbon production (methane + ethane) was highest for AgCu-TNTA with a total CxH2x+2 rate of 23.88 μmol g–1 h–1. Under identical conditions, the CxH2x+2 production rates for Ag-TNTA and Cu-TNTA were 6.54 and 1.39 μmol g–1 h–1, respectively. The ethane selectivity was the highest for AgCu-TNTA with 60.7%, while the ethane selectivity was found to be 15.9 and 10% for the Ag-TNTA and Cu-TNTA, respectively. Adjacent adsorption sites in our photocatalyst develop an asymmetric charge distribution due to quadrupole resonances in large metal nanoparticles and multipole resonances in Ag–Cu heterodimers. Such an asymmetric charge distribution decreases adsorbate–adsorbate repulsion and facilitates C–C coupling of reaction intermediates, which otherwise occurs poorly in TNTAs decorated with small metal nanoparticles.
Vapor growth of binary and ternary phosphorus-based semiconductors into TiO2 ...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@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.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
The document describes the experimental methods used to synthesize and characterize hybrid fibrous red P@TiO2 and black P@TiO2 nanotube membrane materials for photoelectrocatalytic water splitting. TiO2 nanotube membranes were fabricated by anodization and then phosphorus allotropes were deposited via chemical vapor deposition. Characterization techniques included powder XRD, SEM/EDS, STEM/EDS, Raman spectroscopy, XPS, UPS, UV-Vis spectroscopy, KPFM, and gas chromatography to confirm the formation and properties of the hybrid materials. Structural analysis by XRD and Raman spectroscopy validated the incorporation of crystalline red and black phosphorus phases within the TiO2 nanotube membranes.
Harvesting Hot Holes in Plasmon-Coupled Ultrathin Photoanodes for High-Perfor...Pawan Kumar
The harvesting of hot carriers produced by plasmon decay to generate electricity or drive a chemical reaction enables the reduction of the thermalization losses associated with supra-band gap photons in semiconductor photoelectrochemical (PEC) cells. Through the broadband harvesting of light, hot-carrier PEC devices also produce a sensitizing effect in heterojunctions with wide-band gap metal oxide semiconductors possessing good photostability and catalytic activity but poor absorption of visible wavelength photons. There are several reports of hot electrons in Au injected over the Schottky barrier into crystalline TiO2 and subsequently utilized to drive a chemical reaction but very few reports of hot hole harvesting. In this work, we demonstrate the efficient harvesting of hot holes in Au nanoparticles (Au NPs) covered with a thin layer of amorphous TiO2 (a-TiO2). Under AM1.5G 1 sun illumination, photoanodes consisting of a single layer of ∼50 nm diameter Au NPs coated with a 10 nm shell of a-TiO2 (Au@a-TiO2) generated 2.5 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias, rising to 3.7 mA cm–2 in the presence of a hole scavenger (methanol). The quantum yield for hot-carrier-mediated photocurrent generation was estimated to be close to unity for high-energy photons (λ < 420 nm). Au@a-TiO2 photoelectrodes produced a small positive photocurrent of 0.1 mA cm–2 even at a bias of −0.6 V indicating extraction of hot holes even at a strong negative bias. These results together with density functional theory modeling and scanning Kelvin probe force microscope data indicate fast injection of hot holes from Au NPs into a-TiO2 and light harvesting performed near-exclusively by Au NPs. For comparison, Au NPs coated with a 10 nm shell of Al2O3 (Au@Al2O3) generated 0.02 mA cm–2 of photocurrent in 1 M KOH under 0.6 V external bias. These results underscore the critical role played by a-TiO2 in the extraction of holes in Au@a-TiO2 photoanodes, which is not replicated by an ordinary dielectric shell. It is also demonstrated here that an ultrathin photoanode (<100 nm in maximum thickness) can efficiently drive sunlight-driven water splitting.
Flexible and Ultrasoft Inorganic 1D Semiconductor and Heterostructure Systems...Pawan Kumar
This document provides supporting information for a research article on flexible and ultra-soft inorganic semiconductor systems based on tin(II) iodide (SnIP). It includes details from quantum chemical calculations and experimental measurements that characterize the mechanical and structural properties of individual SnIP nanowires. Density functional theory calculations determine the phonon dispersion relations and Raman modes of SnIP under pressure. Experimental force-distance spectroscopy on suspended SnIP nanowires measures the Young's modulus, finding values around 190 GPa along the wire direction. High-pressure x-ray diffraction data and Rietveld refinement are used to calculate the bulk modulus of SnIP as 14.87 GPa, characterizing its compressibility.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
This document summarizes the preparation, characterization, and photocatalytic activity of nitrogen-doped titanium dioxide (TiO2). Yellow nitrogen-doped TiO2 was prepared through a sol-gel method using titanium isopropoxide and urea as precursors. Characterization with XRD, BET, TEM, XPS, and UV-Vis showed the materials were crystalline anatase TiO2 with nitrogen doping extending light absorption into the visible range. Photocatalytic testing demonstrated that nitrogen-doped TiO2 had higher activity for degrading the pesticide 2,4-D under visible light irradiation compared to undoped TiO2.
The document reports on a study investigating the geometrical optimization, spectroscopic analysis, electronic structure, and nuclear magnetic resonance of (S)-(−)-N-(5-Nitro-2-pyridyl) alaninol (SN5N2PLA) using density functional theory calculations. The Fourier transform infrared and Raman spectra were recorded and vibrational assignments were analyzed. Ultraviolet-visible spectra were also recorded and electronic properties like HOMO-LUMO energies were calculated. Nuclear magnetic resonance chemical shifts were calculated and compared to experimental data. The first hyperpolarizability and other properties were computed to investigate the compound's potential as a nonlinear optical material.
The Low-Background HPGE Γ-Spectrometer OBELIX for the Investigation of the Do...IOSRJAP
A new ultra-low-background spectrometer based on a HPGe detector with a sensitive volume of 600 cm 3 was developed to investigate rare nuclear processes, such as resonant neutrino-less double electron capture (0νEC/EC) and double beta decay processes (2ν2β – , 2νβ+EC, 2νEC/EC) to the excited states of daughter nuclei. The spectrometer was installed at the Modane underground laboratory (LSM, France, 4800 m w.e.). Sensitivity of the spectrometer and its background were tested. A new method for the efficiency calibration in measurements of low-active samples was developed. A spectrometer was used for the measurements of low active materials and samples. Results obtained in 395 h investigation of resonant 0νEC/EC decay of 106Cd to the 2718 keV and 2741 keV excited states of 106Pd with ~23.2 g of enriched 106Cd, β +EC, EC/EC decays of 58Ni in measurements of ~21.7 kg sample of natural nickel and 2ν2β – decay of 100Mo sample with the mass of 2588 g to the 0+ , 1130 keV and 2+ , 539.5 keV excited states of 100Ru are presented.
This document summarizes research on electrodepositing silver nanoparticles onto carbon sphere surfaces using a pulse current. Key findings include:
1) Silver nanoparticles were successfully electrodeposited with a size of 100-400nm after 2 minutes using a pulse current.
2) Deposition occurred on accessible carbon surface sites, forming a monolayer of scattered nanoparticles. Continued deposition led to larger particles and multilayers.
3) Pulse current helped manage monolayer deposition compared to direct current, controlling particle size and number of layers.
Academic lecture to MSc students on trace elements in human health, their clinical importance and analytical measurement. Covering the techniques of inductively coupled plasma mass spectrometry (ICP-MS), ICP-optical emission spectroscopy and atomic absorption spectroscopy (AAS). MSC Health and Clinical Science
The document discusses the roles of chemical elements in plants and analytical techniques for analyzing plant samples. It describes essential major and micronutrients for plants as well as toxic elements. It then provides details on elemental analysis techniques including EA for analyzing carbon, hydrogen, nitrogen, sulfur, and oxygen, as well as ICP-AES for determining various elements. ICP-AES involves atomizing a sample in a plasma and detecting element-specific emission spectra. Sample preparation such as microwave digestion is often required prior to analysis.
1) The document describes an experiment using flame atomic absorption spectrophotometry to determine the concentration of copper in samples.
2) Standards of copper nitrate were prepared and used to construct a calibration curve, which was linear from 2-12 ppm. Unknown samples were then analyzed and their copper concentrations calculated based on the curve.
3) Interferences from matrix effects were investigated by analyzing copper solutions of different salts with and without the addition of EDTA.
NO2 Gas Sensing Properties of Carbon Films Fabricated by Arc Discharge Methan...TELKOMNIKA JOURNAL
In this work, a set of experiments has been conducted using arc discharge Methane
decomposition attempting to obtain carbonaceous materials (C-strands) formed between graphite
electrodes. The current-voltage (I-V) characteristics of the fabricated C-strands have been investigated in
the presence and absence of two different gases, NO2 and CO2. The results reveal that the current
passing through the carbon films increases when the concentrations of gases are increased from 200 to
800 ppm. This phenomenon is a result of conductance changes and can be employed in sensing
applications such as gas sensors.
An introduction to the use of ICP-MS in the clinical setting, that goes on to describe some potential new application areas for advanced instrumentation such as HPLC-ICP-MS, laser ablation-ICP-MS and immuno-tagging-ICP-MS for the measurement of biomolecules.
This document describes inductively coupled plasma atomic emission spectroscopy (ICP-AES) and its applications. ICP-AES involves using inductively coupled plasma to excite sample atoms and ions, causing them to emit electromagnetic radiation at wavelengths characteristic of the elements present. This allows simultaneous multi-element analysis. The document discusses various applications of ICP-AES in environmental analysis, petrochemical analysis, metallurgy, geology, food analysis and more. It also provides details on instrumentation parameters, detection limits, sample preparation and references.
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates heat transfer through carbon nanotube composites, focusing on the conduction mode.
2. It summarizes the synthesis and preparation of aligned multi-walled carbon nanotube samples embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The specific heat and thermal conductivity of the samples are measured from 300 to 400K. The specific heat of the aligned nanotube sample has weaker temperature dependence than the random films and bulk graphite. The thermal conductivity of the aligned sample increases with temperature, while the random films and graphite show a
The document discusses the benefits of ICP-MS/MS technology for challenging clinical trace element analysis applications. ICP-MS/MS can overcome limitations of single quadrupole ICP-MS by removing interferences through reaction cell modes. Examples show it can achieve lower detection limits than ICP-QMS for applications like measuring titanium in serum and urine, selenium in the presence of gadolinium, and manganese in whole blood. The document concludes ICP-MS/MS is suitable for applications where collision cell modes are insufficient and provides capabilities for addressing abundance sensitivity issues at lower cost than other high-end techniques.
The document discusses inductively coupled plasma mass spectrometry (ICP-MS), an analytical technique used for elemental determinations. [1] ICP-MS can detect elements at very low concentrations, analyze all elements simultaneously, and provide isotopic information. [2] It has various applications in pharmaceutical analysis including drug development, quality control, clinical trials, and detection of impurities. [3] Next generation ICP-MS instruments offer improved stability, flexibility, and performance for pharmaceutical applications.
Separation of mercury from VOC’s and selective detection using gold film ama...Jennifer Maclachlan
Presented at the Spring 2015 National Meeting of the American Chemical Society in Denver, CO on March 23, 2015 on the Analytical Chemistry Division program track.
Presentation overview:
We used a sensitive but nonspecific photoionization detector (PID) with a 10.6eV lamp to measure mercury, which has an ionization potential of 10.43eV.
The PID responds to both mercury and VOC’s so the VOC’s have to be removed to make the technique specific for mercury.
The chemistry of the gold/mercury amalgam makes this method specific for mercury and eliminates interferences from VOC’s.
This technique also concentrates the sample making the method sensitive to sub ppb levels.
Analysis for and quantification of sulfur in crude oil, natural gas, petrochemicals, and industrial chemicals is critical to ensuring quality, process control, and safety for refinery, processors, and users. Understanding the speciation and concentration of sulfur compounds is vital in the hydrocarbon processing industry. Gas chromatography with sulfur chemiluminescence detection (GC-SCD) is one of the most powerful tools for sulfur analysis of hydrocarbons. This poster showcases the use of a new SCD for analysis according to various ASTM methods.
This document discusses a study analyzing the molecular structure, vibrational spectra, and electronic properties of 4-Methoxy-40-Nitrobiphenyl (4M40NBPL) using density functional theory computations. Key findings include:
1) Geometry optimization and vibrational frequency calculations were performed using B3LYP/6-31G(d,p) to determine the equilibrium structure and analyze vibrational modes.
2) Experimental FT-IR and FT-Raman spectra were recorded and compared to theoretical spectra, and vibrational assignments were made with total energy distribution analysis.
3) Electronic structure calculations including NBO analysis, HOMO-LUMO energies, and NMR studies provided insights into molecular
The document defines alcoholism as a chronic, progressive disease where a person has lost control over their drinking to the point where it is interfering with important areas of their life like family, friends, work, school, or health. Alcoholism is described as a disease because it has predictable stages of progression, is considered permanent once control over drinking is lost, and is treatable through abstinence and long-term support. While physical addiction occurs in a small percentage of alcoholics, the definition is based on the consequences of drinking rather than physical addiction.
La Internet de las Cosas ha llegado para quedarse, y las empresas deben adaptarse a esa realidad. La sociedad ha cambiado, las personas se han digitalizado, incluso antes que las empresas, y la forma en la que te comunicas con tus clientes debe cambiar ya... bienvenidos a la era del "Marketing de las Cosas"
This document discusses the differences between formative and summative interventions with children. Formative interventions focus on a child's development and inner instincts, addressing their unmet needs through relationships. Summative interventions focus on behavior and consequences. The document advocates for formative attachment pedagogy, where counseling creates a context for emotional maturation by addressing a child's needs for safety, co-regulation of feelings, and freedom from daily frustrations. Behavior may indicate what is missing for a child, such as feelings of safety from alarming feelings or pursuit of co-regulation. Development nurtures children but does not teach them skills to manage feelings without proper attachment.
Cricigrama y sopa de letras natalia martinez 10 1nathalia1314
This document contains a word search puzzle and crossword puzzle featuring the names of Spanish rock bands. The word search includes band names like Aterciopelados, Barón Rojo, Caifanes, Maná, Molotov, Saratoga, and Zoe. The crossword clues include bands and songs, such as Café Tacuba's "Eres" and Molotov's 1992 single "Nubes".
Este documento descreve o cronograma das eleições para o Parlamento dos Jovens em uma escola. Apresenta as datas importantes como o prazo para apresentação de listas em 30 de novembro, o debate com o deputado em 18 de janeiro e a sessão escolar em 20 de janeiro. Também fornece detalhes sobre as listas concorrentes e os nomes dos alunos candidatos.
The document reports on a study investigating the geometrical optimization, spectroscopic analysis, electronic structure, and nuclear magnetic resonance of (S)-(−)-N-(5-Nitro-2-pyridyl) alaninol (SN5N2PLA) using density functional theory calculations. The Fourier transform infrared and Raman spectra were recorded and vibrational assignments were analyzed. Ultraviolet-visible spectra were also recorded and electronic properties like HOMO-LUMO energies were calculated. Nuclear magnetic resonance chemical shifts were calculated and compared to experimental data. The first hyperpolarizability and other properties were computed to investigate the compound's potential as a nonlinear optical material.
The Low-Background HPGE Γ-Spectrometer OBELIX for the Investigation of the Do...IOSRJAP
A new ultra-low-background spectrometer based on a HPGe detector with a sensitive volume of 600 cm 3 was developed to investigate rare nuclear processes, such as resonant neutrino-less double electron capture (0νEC/EC) and double beta decay processes (2ν2β – , 2νβ+EC, 2νEC/EC) to the excited states of daughter nuclei. The spectrometer was installed at the Modane underground laboratory (LSM, France, 4800 m w.e.). Sensitivity of the spectrometer and its background were tested. A new method for the efficiency calibration in measurements of low-active samples was developed. A spectrometer was used for the measurements of low active materials and samples. Results obtained in 395 h investigation of resonant 0νEC/EC decay of 106Cd to the 2718 keV and 2741 keV excited states of 106Pd with ~23.2 g of enriched 106Cd, β +EC, EC/EC decays of 58Ni in measurements of ~21.7 kg sample of natural nickel and 2ν2β – decay of 100Mo sample with the mass of 2588 g to the 0+ , 1130 keV and 2+ , 539.5 keV excited states of 100Ru are presented.
This document summarizes research on electrodepositing silver nanoparticles onto carbon sphere surfaces using a pulse current. Key findings include:
1) Silver nanoparticles were successfully electrodeposited with a size of 100-400nm after 2 minutes using a pulse current.
2) Deposition occurred on accessible carbon surface sites, forming a monolayer of scattered nanoparticles. Continued deposition led to larger particles and multilayers.
3) Pulse current helped manage monolayer deposition compared to direct current, controlling particle size and number of layers.
Academic lecture to MSc students on trace elements in human health, their clinical importance and analytical measurement. Covering the techniques of inductively coupled plasma mass spectrometry (ICP-MS), ICP-optical emission spectroscopy and atomic absorption spectroscopy (AAS). MSC Health and Clinical Science
The document discusses the roles of chemical elements in plants and analytical techniques for analyzing plant samples. It describes essential major and micronutrients for plants as well as toxic elements. It then provides details on elemental analysis techniques including EA for analyzing carbon, hydrogen, nitrogen, sulfur, and oxygen, as well as ICP-AES for determining various elements. ICP-AES involves atomizing a sample in a plasma and detecting element-specific emission spectra. Sample preparation such as microwave digestion is often required prior to analysis.
1) The document describes an experiment using flame atomic absorption spectrophotometry to determine the concentration of copper in samples.
2) Standards of copper nitrate were prepared and used to construct a calibration curve, which was linear from 2-12 ppm. Unknown samples were then analyzed and their copper concentrations calculated based on the curve.
3) Interferences from matrix effects were investigated by analyzing copper solutions of different salts with and without the addition of EDTA.
NO2 Gas Sensing Properties of Carbon Films Fabricated by Arc Discharge Methan...TELKOMNIKA JOURNAL
In this work, a set of experiments has been conducted using arc discharge Methane
decomposition attempting to obtain carbonaceous materials (C-strands) formed between graphite
electrodes. The current-voltage (I-V) characteristics of the fabricated C-strands have been investigated in
the presence and absence of two different gases, NO2 and CO2. The results reveal that the current
passing through the carbon films increases when the concentrations of gases are increased from 200 to
800 ppm. This phenomenon is a result of conductance changes and can be employed in sensing
applications such as gas sensors.
An introduction to the use of ICP-MS in the clinical setting, that goes on to describe some potential new application areas for advanced instrumentation such as HPLC-ICP-MS, laser ablation-ICP-MS and immuno-tagging-ICP-MS for the measurement of biomolecules.
This document describes inductively coupled plasma atomic emission spectroscopy (ICP-AES) and its applications. ICP-AES involves using inductively coupled plasma to excite sample atoms and ions, causing them to emit electromagnetic radiation at wavelengths characteristic of the elements present. This allows simultaneous multi-element analysis. The document discusses various applications of ICP-AES in environmental analysis, petrochemical analysis, metallurgy, geology, food analysis and more. It also provides details on instrumentation parameters, detection limits, sample preparation and references.
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates heat transfer through carbon nanotube composites, focusing on the conduction mode.
2. It summarizes the synthesis and preparation of aligned multi-walled carbon nanotube samples embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The specific heat and thermal conductivity of the samples are measured from 300 to 400K. The specific heat of the aligned nanotube sample has weaker temperature dependence than the random films and bulk graphite. The thermal conductivity of the aligned sample increases with temperature, while the random films and graphite show a
The document discusses the benefits of ICP-MS/MS technology for challenging clinical trace element analysis applications. ICP-MS/MS can overcome limitations of single quadrupole ICP-MS by removing interferences through reaction cell modes. Examples show it can achieve lower detection limits than ICP-QMS for applications like measuring titanium in serum and urine, selenium in the presence of gadolinium, and manganese in whole blood. The document concludes ICP-MS/MS is suitable for applications where collision cell modes are insufficient and provides capabilities for addressing abundance sensitivity issues at lower cost than other high-end techniques.
The document discusses inductively coupled plasma mass spectrometry (ICP-MS), an analytical technique used for elemental determinations. [1] ICP-MS can detect elements at very low concentrations, analyze all elements simultaneously, and provide isotopic information. [2] It has various applications in pharmaceutical analysis including drug development, quality control, clinical trials, and detection of impurities. [3] Next generation ICP-MS instruments offer improved stability, flexibility, and performance for pharmaceutical applications.
Separation of mercury from VOC’s and selective detection using gold film ama...Jennifer Maclachlan
Presented at the Spring 2015 National Meeting of the American Chemical Society in Denver, CO on March 23, 2015 on the Analytical Chemistry Division program track.
Presentation overview:
We used a sensitive but nonspecific photoionization detector (PID) with a 10.6eV lamp to measure mercury, which has an ionization potential of 10.43eV.
The PID responds to both mercury and VOC’s so the VOC’s have to be removed to make the technique specific for mercury.
The chemistry of the gold/mercury amalgam makes this method specific for mercury and eliminates interferences from VOC’s.
This technique also concentrates the sample making the method sensitive to sub ppb levels.
Analysis for and quantification of sulfur in crude oil, natural gas, petrochemicals, and industrial chemicals is critical to ensuring quality, process control, and safety for refinery, processors, and users. Understanding the speciation and concentration of sulfur compounds is vital in the hydrocarbon processing industry. Gas chromatography with sulfur chemiluminescence detection (GC-SCD) is one of the most powerful tools for sulfur analysis of hydrocarbons. This poster showcases the use of a new SCD for analysis according to various ASTM methods.
This document discusses a study analyzing the molecular structure, vibrational spectra, and electronic properties of 4-Methoxy-40-Nitrobiphenyl (4M40NBPL) using density functional theory computations. Key findings include:
1) Geometry optimization and vibrational frequency calculations were performed using B3LYP/6-31G(d,p) to determine the equilibrium structure and analyze vibrational modes.
2) Experimental FT-IR and FT-Raman spectra were recorded and compared to theoretical spectra, and vibrational assignments were made with total energy distribution analysis.
3) Electronic structure calculations including NBO analysis, HOMO-LUMO energies, and NMR studies provided insights into molecular
The document defines alcoholism as a chronic, progressive disease where a person has lost control over their drinking to the point where it is interfering with important areas of their life like family, friends, work, school, or health. Alcoholism is described as a disease because it has predictable stages of progression, is considered permanent once control over drinking is lost, and is treatable through abstinence and long-term support. While physical addiction occurs in a small percentage of alcoholics, the definition is based on the consequences of drinking rather than physical addiction.
La Internet de las Cosas ha llegado para quedarse, y las empresas deben adaptarse a esa realidad. La sociedad ha cambiado, las personas se han digitalizado, incluso antes que las empresas, y la forma en la que te comunicas con tus clientes debe cambiar ya... bienvenidos a la era del "Marketing de las Cosas"
This document discusses the differences between formative and summative interventions with children. Formative interventions focus on a child's development and inner instincts, addressing their unmet needs through relationships. Summative interventions focus on behavior and consequences. The document advocates for formative attachment pedagogy, where counseling creates a context for emotional maturation by addressing a child's needs for safety, co-regulation of feelings, and freedom from daily frustrations. Behavior may indicate what is missing for a child, such as feelings of safety from alarming feelings or pursuit of co-regulation. Development nurtures children but does not teach them skills to manage feelings without proper attachment.
Cricigrama y sopa de letras natalia martinez 10 1nathalia1314
This document contains a word search puzzle and crossword puzzle featuring the names of Spanish rock bands. The word search includes band names like Aterciopelados, Barón Rojo, Caifanes, Maná, Molotov, Saratoga, and Zoe. The crossword clues include bands and songs, such as Café Tacuba's "Eres" and Molotov's 1992 single "Nubes".
Este documento descreve o cronograma das eleições para o Parlamento dos Jovens em uma escola. Apresenta as datas importantes como o prazo para apresentação de listas em 30 de novembro, o debate com o deputado em 18 de janeiro e a sessão escolar em 20 de janeiro. Também fornece detalhes sobre as listas concorrentes e os nomes dos alunos candidatos.
El cóndor andino es el ave no marina de mayor envergadura del planeta. Habita en los Andes y costas adyacentes de Sudamérica. Se alimenta de animales muertos, pudiendo ingerir hasta 5 kg de carne por día e incluso ayunar por 5 semanas. Es un ave monógama cuya reproducción dura entre 2 a 3 años, teniendo el periodo de incubación más largo entre las aves de presa a unos 56-60 días.
The document discusses 3D scanning technologies that can measure physical objects and convert the point cloud data into a usable digital format like a mesh or CAD model. It also describes 3D printing as an additive manufacturing process that creates 3D objects by laying down successive layers of material. Finally, the document lists some applications of 3D scanning such as making spare parts, enabling cheaper space exploration, and driving social change.
El documento resume las principales consecuencias de la Segunda Guerra Mundial, incluyendo el Holocausto que resultó en más de 6 millones de muertes, principalmente de judíos; la creación de las Naciones Unidas para prevenir futuros conflictos; y la Declaración Universal de los Derechos Humanos de 1948 para proteger los derechos fundamentales en respuesta a los horrores de la guerra.
Este documento trata sobre la toma de decisiones en las organizaciones. Explica que la toma de decisiones es muy importante para el éxito u fracaso de las organizaciones. Describe el proceso de toma de decisiones que incluye identificar el problema, los criterios de decisión, desarrollar alternativas, analizarlas, seleccionar una y evaluarla. También habla sobre la toma de decisiones en situaciones de crisis, donde las autoridades asumen un rol más importante, y la toma de decisiones estratégicas a nivel directivo que determinan metas
El documento describe la Hidrovía Paraguay-Paraná-Uruguay, un proyecto de transporte fluvial que aprovecha el sistema formado por los ríos Paraná, Paraguay y Uruguay. El proyecto, promovido por Argentina, Bolivia, Brasil, Paraguay y Uruguay, permite el transporte de grandes volúmenes de carga a bajo costo entre los países. También describe brevemente la Hidrovía Uruguay-Brasil, un proyecto similar en el río Uruguay.
Pikaopas yrityssivun luontiin. Opas esittelee vaiheittain yrityssivun luomisen alkaen valmistelutehtävistä, jotka kannattaa tehdä ennen työkalun käyttöä. Esitys on luotu auttamaan pieniä yrityksiä sähköisessä markkinoinnissaan.
El documento describe el sistema fluvial formado por los ríos Paraná y Paraguay, que ha sido utilizado históricamente para el transporte y comercio. Actualmente, cinco países (Brasil, Bolivia, Paraguay, Argentina y Uruguay) buscan mejorar la navegabilidad de esta vía fluvial a través de obras como dragado y rectificación de curvas para permitir el tránsito continuo de embarcaciones. Si bien esto podría aumentar la producción agrícola y minera, también representa riesgos para el delicado ecosist
This document is about activities planned by Pau and Lorena. It discusses their upcoming schedule of events for an unknown period of time. The activities are not described in detail, but several are mentioned as being organized by Pau and Lorena.
The document discusses various aspects of email marketing and viral marketing campaigns. It provides tips for improving email open and click-through rates by optimizing the subject line, timing, list quality, and ensuring a strong value proposition. It also outlines the key elements of a successful viral campaign, including tapping existing resources and networks to coordinate a launch that makes content appear suddenly popular. Lastly, it reviews the CAN-SPAM act and legal requirements for commercial emails.
El documento describe la evolución del derecho común en Europa desde la antigüedad hasta la edad moderna. Comenzó con el derecho romano y canónico que se convirtió en el derecho común debido a su enseñanza en las universidades. Los glosadores explicaron el derecho romano y los postglosadores lo comentaron y aplicaron. Más tarde, surgió la escuela alemana que concibió el derecho como emanación del espíritu de cada pueblo.
La obra narra los hechos de la campaña de Rusia de 1812 encabezada por Napoleón. Se describe la batalla de Sbodonovo donde lucha el pelotón 326 de Línea formado por soldados de diferentes nacionalidades. Aunque ganan los franceses, posteriormente Moscú es incendiada y en el camino de vuelta a Francia el ejército francés es diezmado por el ejército ruso, llegando el pelotón 326 de Línea a España con solo 11 miembros, un año y medio después de abandonar M
Consistently High Voc Values in p-i-n Type Perovskite Solar Cells Using Ni3+-...Pawan Kumar
Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high Voc values albeit inconsistently. In this report, a NiO nanomesh with Ni3+ defect grown by the hydrothermal method was used to obtain PSCs with Voc values that consistently exceeded 1.10 V (champion Voc = 1.14 V). A champion device photoconversion efficiency of 17.75% was observed. Density functional theory modeling was used to understand the interfacial properties of the NiO/perovskite interface. The PCE of PSCs constructed using the Ni3+-doped NiO nanomesh HTL was ∼34% higher than that of conventional compact NiO-based perovskite solar cells. A suite of characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy, intensity-modulated photocurrent spectroscopy, intensity-modulated photovoltage spectroscopy, time-resolved photoluminescence, steady-state photoluminescence, and Kelvin probe force microscopy provided evidence of better film quality, enhanced charge transfer, and suppressed charge recombination in PSCs based on hydrothermally grown NiO nanostructures.
Metal-Free Sulfonate/Sulfate-Functionalized Carbon Nitride for Direct Convers...Pawan Kumar
Metal-free heteroatom-doped carbonaceous materials such as carbon nitride (CN) with secondary/tertiary nitrogen-rich catalytic centers as well as chemical and thermal resilience can potentially serve as catalysts for many organic reactions. However, because of the stable alternate Csp2–Nsp2 configuration of N-linked heptazine units (C6N7), the chemical modification of CN via doping and functionalization has been a critical challenge. Herein, we report an exceptional 9.2% sulfur content in CN with sulfonate/sulfate functional groups (CNS) via a one-step in situ synthesis approach. When used as a catalyst for the dehydration/hydration of glucose, CNS catalysts demonstrate a relatively high yield and selectivity toward levulinic acid, LLA, (≈48% yield with 57% selectivity) production. CNS’s high activity of direct conversion of glucose to LLA can be attributed to the synergistic catalytic effects of multiple sulfur functionalities, better dispersibility, and microstructural porosity. The synthesized CNS catalysts offer an energy efficient direct LLA production route to bypass the multistep process of sugar to LLA conversion.
Unusual Electronic Properties of Cellulose Nanocrystals Conjugated to Cobalt ...Pawan Kumar
Octacarboxylated cobalt phthalocyanine (CoPc) was covalently conjugated to cellulose nanocrystals (CNCs) by employing an esterification protocol. Solid-state NMR, X-ray photoelectron spectroscopy (XPS), Raman, and infrared spectra were used to verify and study the nature of covalent attachment responsible for the immobilization of CoPc on the CNC surface. The covalent attachment was investigated from a theoretical simulation perspective using dispersion-corrected density functional theory (DFT) calculations, which verified the stable bond formation between CNC and CoPc. CoPc is an organic semiconductor with a high exciton binding energy, and CNCs are known to be insulating. Yet, Kelvin probe force microscopy (KPFM) indicated charge carrier generation and long-lived charge separation in the CNC–CoPc conjugate compared to pristine CoPc under visible light illumination. Such behavior is more typical of a semiconductor nanocomposite. The CNC–CoPc conjugate exhibited superior performance in the visible-light-driven surface photocatalytic reduction of 4-nitrobenzenethiol (4-NBT) to p,p′-dimercaptoazobenzene (DMAB) and photodegradation of rhodamine B.
This chapter describes the fabrication of a zirconia nanoparticle-decorated reduced graphene oxide (ZrO2/rGO) nanocomposite for an electrochemical sensor to detect the anticancer drug regorafenib. Characterization using XRD, FT-IR, XPS, TEM and EDX confirmed the successful synthesis of ZrO2 nanoparticles on rGO. Electrochemical tests using cyclic voltammetry and differential pulse voltammetry showed the ZrO2/rGO modified electrode has excellent electrocatalytic activity for regorafenib oxidation, with a wide linear detection range of 11-343 nM and a low detection limit of 3.7 nM. The sensor also demonstrated good
Images and data in the presentation are subject to copyright. Please contact redhwanm(at)mcmaster(dot)ca for permission if you want to use any of its contents.
Awais Thesis Final Defense ppt updated.pptxNaseem89
This document outlines a study on synthesizing and characterizing Cu-doped ZIF-8 catalysts for electrocatalytic CO2 reduction. Cu-doped ZIF-8 materials with various Cu loadings were synthesized using a solvothermal method and characterized using techniques like XRD, SEM, EDX, BET. These catalysts were then used in an electrochemical cell to reduce CO2 and the products were analyzed. Cu10%ZIF-8 showed the highest CO faradaic efficiency of 62.26% and Cu30%ZIF-8 achieved the highest current density of -40 mA/cm2, indicating improved selectivity and activity for CO2 electroreduction compared to pure ZIF
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after 24 h irradiation was 9934 μmol g−1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride 145 μmol g−1cat under identical conditions. The presence of triethylamine was found to be vital for the higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
The document describes a study that deposited electrochemically reduced graphene oxide (ERGO) on aluminium copper (AlCu) substrates using electrodeposition at different voltage windows and cycles to produce humidity sensors. ERGO was deposited at voltage windows of 0.3V to -0.2V and 0.3V to -0.6V, with 1, 2, or 3 cycles within each window. Raman spectroscopy showed the deposited ERGO had characteristic D, G, and 2D bands. Humidity sensing tests found the sample deposited at 0.3V to -0.6V for 2 cycles had the highest sensitivity of 67.63% due to its thicker nanoporous structure providing a larger surface area to absorb water
This document discusses a study on enhancing laser-induced plasma emission from gadolinium oxide samples using microwaves in argon gas. The study aims to improve laser-induced breakdown spectroscopy (LIBS) for potential nuclear fuel material analysis. When microwaves were introduced into the laser-induced plasma, total emission intensity from gadolinium significantly increased. Emission lines could be more clearly identified with lower background intensity and disturbance from molecular bands. Microwave-assisted laser plasma showed enhancement factors of 40-45 times for neutral and ionic gadolinium lines. Plasma temperatures were also higher with microwaves. The method shows promise for improving impurity analysis in complex nuclear fuel materials.
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.
Atomic absorption spectroscopy (AAS) is a technique used to determine the concentration of elemental metals in plant samples. It works by converting the metal in a sample into gaseous atoms, and measuring the absorption of light from a hollow cathode lamp at a wavelength specific to the metal. The technique requires a flame to atomize the sample and is very sensitive, allowing detection of minute amounts of metals. It has advantages over other techniques in being specific, rapid, and requiring small sample sizes. However, it is limited to analysis of metals and can be affected by other elements present in the sample. AAS provides an important tool for analyzing plant nutrition and studying the impact of metals.
The document summarizes research on the electrocatalytic reduction of CO2 to produce ethylene using copper-based nanoparticles supported on carbon. Key points:
1. Copper oxide nanoparticles with an initial size of 20 nm were synthesized on carbon and fragmented into smaller 2-4 nm nanoparticles during CO2 electroreduction, improving ethylene selectivity.
2. Operando transmission electron microscopy showed the nanoparticles distort and break apart over time, correlated with increasing ethylene production.
3. In situ X-ray absorption spectroscopy indicated the copper oxidation state decreases to metallic copper during electrolysis, the active state for CO2 reduction.
4. The fragmented nanoparticle morphology, combining small particles and compact
Mixed-Valence Single-Atom Catalyst Derived from Functionalized GraphenePawan Kumar
Single-atom catalysts (SACs) aim at bridging the gap between homogeneous and heterogeneous catalysis. The challenge is the development of materials with ligands enabling coordination of metal atoms in different valence states, and preventing leaching or nanoparticle formation. Graphene functionalized with nitrile groups (cyanographene) is herein employed for the robust coordination of Cu(II) ions, which are partially reduced to Cu(I) due to graphene-induced charge transfer. Inspired by nature's selection of Cu(I) in enzymes for oxygen activation, this 2D mixed-valence SAC performs flawlessly in two O2-mediated reactions: the oxidative coupling of amines and the oxidation of benzylic CH bonds toward high-value pharmaceutical synthons. High conversions (up to 98%), selectivities (up to 99%), and recyclability are attained with very low metal loadings in the reaction. The synergistic effect of Cu(II) and Cu(I) is the essential part in the reaction mechanism. The developed strategy opens the door to a broad portfolio of other SACs via their coordination to various functional groups of graphene, as demonstrated by successful entrapment of FeIII/FeII single atoms to carboxy-graphene.
Synthesis of 2-aminocyclopent-1-ene-1-carbodithioic acid (ACA) Capped Silver ...IJERA Editor
The present work deals with the formation, morphology and photophysical activity of the 2-aminocyclopent-1-ene-1-carbodithioic acid (ACA) Capped Silver nanoparticles via chemical reduction method. The method utilizes a simple chemical reaction of silver idodide and sodium borohydride. The advantages of this method are ease of preparation, convenience in use and especially, that the obtained silver nano particles are uniform in their shapes and sizes. This is important for fluorescence & bio-evolution measurements. Furthermore, UV-visible (UV-vis) spectroscopy is employed to monitor the formation process of the nano particles and to determine the optimum conditions for the preparation of stable and highly fluorescence-active silver colloids. Specifically, we observed changes in the shapes of the silver nano particles during the formation. This may be helpful in understanding the growth of the nano particles and creates a new dimension in controlling the shapes of the nano particles.SEM, TEM and XRD studies are carried out. The suitability of ACA capped Ag-NPs as Biomarkers is also Tested by Fluorescence study.
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.
Noble Metal Free, Visible Light Driven Photocatalysis Using TiO2 Nanotube Arr...Pawan Kumar
Bulk g-C3N4 is an earth-abundant, easily synthesizable, and exceptionally stable photocatalyst with an electronic bandgap of 2.7 eV. Herein, the concepts of P-doping and size quantization are combined to synthesize highly fluorescent P-doped carbon nitride quantum dots (CNPQDs) with a bandgap of 2.1 eV. CNPQDs are hosted on anatase-phase and rutile-phase TiO2 nanotube array scaffolds, and examined as photoanodes for sunlight-driven water-splitting and as photocatalysts for surface catalytic reactions. Square-shaped rutile phase TiO2 nanotube arrays (STNAs) decorated with CNPQDs (CNPQD-STNA) generate 2.54 mA cm−2 photocurrent under AM1.5 G simulated sunlight. A champion hydrogen evolution rate of 22 µmol h−1 corresponds to a Faradaic efficiency of 93.2%. In conjunction with Ag nanoparticles (NPs), the CNPQD-STNA hybrid is also found to be an excellent plexcitonic photocatalyst for the visible light-driven transformation of 4-nitrobenzenethiol (4-NBT) to dimercaptoazobenzene (DMAB), producing reaction completion at a laser power of 1 mW (532 nm) while Ag NP/TNA and Ag NP/STNA photocatalysts cannot complete this transformation even at 10 mW laser power. The results point the way forward for photochemically robust, noble metal free, visible light harvesting photoacatalysts based on nanostructured heterojunctions of graphenic frameworks with TiO2.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
2. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
90
Fig. 1. Schematic diagram and a picture of the boron container
For the analysis of geological and biological
materials 150–200 mg were sealed in high purity quartz
vials (Suprasil AN, Heraeus) and then packed in the
boron shielded container.
Irradiation
The bare and boron-shielded samples and flux
monitors were irradiated for 24 hours in the Budapest
Research Reactor at a thermal neutron flux density of
1.5.1013 n.cm–2.s–1, thermal-to-epithermal neutron flux
ratio f = th/ epi = 49 and = 0.015, where the
epithermal flux is represented by the 1/E1+ function
and is a form factor. Following boron-covered
irradiations, all samples were measured after a minimum
delay of approximately 1 hour on account of the
substantial reduction of matrix activities 24Na
(T1/2 = 14.95 h), 32P (T1/2 = 14.28 d) and 82Br
(T1/2 = 1.47 d). Following bare irradiations, the first
measurement of the samples were carried out after 4–5
days. Counting times varied between 1800 seconds and
10 hours. Gamma-spectrometric measurements were
performed with a Canberra HPGe detector (energy
resolution of 1.74 keV and relative efficiency of 36% for
the 1332.5 keV 60Co line), and associated linear
electronics consisting of an 8K ADC and an
ACCUSPEC/B type 16K MCA board. The spectrometer
was equipped with a Westphal-type Loss-Free Counting
(LFC) module operated in Dual Spectrum Mode
providing full compensation for all kind of counting
losses. The gamma-ray spectra were evaluated by the
program HYPERMET-PC,6 involving automatic peak
search, energy calibration, net peak counts computation.
The quantitative evaluation of the INAA multi-element
measurements was based on the k0 standardization
method using gold and zirconium flux monitors co-
irradiated with the samples. An in-house program
NAACNC was used for isotope identification and
elemental concentration calculations.7
The IAEA-Soil-7 reference material was analyzed by
ENAA to test the accuracy of the implemented
technique.
Results
Determination of boron activation ratios
The activation ratios were calculated for individual
(n, ) reactions using the specific activities of samples
induced in bare and filtered irradiations.
3. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
91
The improvement achieved by filtered irradiations may
be expressed as the so-called improvement factor:1
)1(
)2(
B
B
B
R
R
IF ,
where RB(1) refers to the determinant, and RB(2) refers to
the dominant interfering element . Table 2 lists the
nuclear data for the radionuclides used, RCd and RB and
the calculated IFB for interferences of 24Na and 46Sc.
Sodium and scandium were chosen as typical
interferences always present in biological and geological
samples.
Effect of the boron filter on the neutron flux distribution
Boron’s absorption cross section follows the 1/v law
over a wide energy range (from about 0.001 to a few
hundred eV). The resulting EB = 15.2 eV cutoff for
500 mg B/cm2 surface density allows a very effective
depression of strongly activating 1/v and low resonance
target isotopes while reducing only slightly the
activation of analytically important, higher than 10 eV
resonance elements such as As, Sb, Th, Zn, U (Fig. 2).
An additional advantage of epiboron NAA is the
significant reduction of the analysis turn-around time.
Using a boron shield, the measurements could be started
after about 1 hour waiting time. Consequently, some
short-lived trace elements as Mn, As, Mg, Ti, ,etc. can
be determined instrumentally with higher accuracy and
minimum delay (Fig. 3).
Fig. 2. Excerpt of a MathCad program showing the approximate neutron flux distributions in the
rotating channel No. 17 of the Budapest Research Reactor using 1 mm Cd and 500 mg/cm2
natural boron filters
4. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
92
5. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
93
Table 2. Nuclear data, Cd B ratios and improvement factors for some (n, ) reactions of interest
Nuclear data Activation ratio Improvement factor
Element Nuclear reaction
r, eV I0/ 0 RCd RB SD, % IFB(Na) IFB(Sc)
Ag 109
Ag(n, )110m
Ag 6.08 16.7 – 26 (3) 0.58 0.95
As 75
As(n, )76
As 106 13.6 4.2 6.2 (2) 2.38 3.91
Au 197
Au(n, )198
Au 5.7 15.7 3.9 26 (1) 0.56 0.92
Br 81
Br(n, )82
Br 152 19.3 – 4.7 (1) 3.16 5.16
Ce 140
Ce(n, )141
Ce 7200 0.83 – 115 0.13 0.21
Co 59
Co(n, )60
Co 136 1.99 – 45 (4) 0.34 0.54
Cs 133
Cs(n, )134
Cs 9.27 13.2 – 15 (4) 1.06 1.73
151
Eu(n, )152
Eu 0.448 0.87 – 440 (4) 0.03 0.06Eu
153
Eu(n, )154
Eu 5.8 5.66 – 40 (1) 0.37 0.61
Fe 58
Fe(n, )59
Fe 637 0.97 50 92 (2) 0.16 0.26
La 139
La(n, )140
La 76 1.24 – 69 (2) 0.22 0.35
Na 23
Na(n, )24
Na 3380 0.59 – 220 (5) – –
Rb 85
Rb(n, )86
Rb 839 14.8 – 4.7 (3) 3.15 5.16
121
Sb(n, )122
Sb 13.1 33.0 – 7.6 (5) 1.94 3.20Sb
123
Sb(n, )124
Sb 28.2 28.8 – 6.1 (3) 2.46 4.08
Sc 45
Sc(n, )46
Sc 5130 0.43 103 589 (5) – –
Se 74
Se(n, )75
Se 29.4 10.8 – 13 (6) 1.16 1.91
Th 232
Th(n, )233
Th/233
Pa 54.4 11.5 – 8.8 (2) 1.68 2.75
64
Zn(n, )65
Zn 2560 1.91 26 30 (6) 0.49 0.79Zn
68
Zn(n, )69m
Zn 590 3.19 16 18 0.81 1.34
94
Zr(n, )95
Zr 6260 5.31 10 9.3 (2) 1.60 2.63Zr
96
Zr(n, )97
Zr/97m
Nb 338 251.6 1.2 1.4 (2) 10.6 17.3
U 238
U(n, )239
U/239
Np 16.9 103.4 – 4.4 (2) 3.36 5.51
Fig. 3. A typical spectrum region of a geological sample irradiated for 24 hours in a boron filter and measured after 30-minute waiting time
6. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
94
Fig. 4. Gamma-ray spectra of the SRM NIST -613 Trace Element in Glass samples irradiated with and without a boron filter. Upper spectrum:
without B-filter ti = 24 hours, td = 53 hours, tc = 1800 s; lower spectrum: with B-filter ti = 24 hours, td =6 hours, tc = 3600 s
Table 3. Analysis results of SRM IAEA-Soil-7 by INAA and ENAA
Analysis results, mg/kg (mean SD%)
Element Certified value
by IAEA
INAA ENAA
As 13.4 (6) 14.3 (5) 14.3 (5)
Ce 61 (11) 57 (5) 57 (5)
Co 8.9 (10) 8. 7 (5) 8.9 (6)
Cr 60 (21) 67 (5) **
Cs 5.4 (14) 5.4 (14) 5.2 (10)
Br* 3–10 5.4 (6) 5.3 (5)
Hf 5.1 (7) 4.9 (5) **
La 28 (4 ) 28 (5) 25 (7)
Rb 51 (9) 52 (7) 49 (8)
Sb 1.7 (12) 1.8 (10) 1.6 (5)
Sc 8.3 (13) 8.4 (4) –
Sm 5.1 (7) 4.9 (10) **
Ta 0.8 (25) 0.7 (10) **
Th 8.2 (13) 7.9 (6) 8.2 (6)
U 2.6 (21) 2.4 (6) 2.5 (5)
Yb 2.4 (15) 2.2 (5) **
Zn 104 (6 ) 107 (6) 106 (6)
Zr 185 (6 ) 198 (12) 185 (6)
Tb 0.6 (33) 0.7 (19) **
Eu 1 (20) 0.9 (7) 0.8 (8)
Ca 163000* 160140 (6) **
Fe 25700* 25484 (4) 27336 (9)
* Information value.
** No ENAA results due to the lack of RB factors.
7. R. SZ KE, I. SZIKLAI-LÁSZLÓ: EPIBORON NAA: AN OPTION TO ANALYZE UNFAVORABLE MATRICES
95
Table 4. Comparison of the detection limits of INAA and ENAA for some elements
in SRM IAEA-Soil-7
LD, mg/kg
Element
with INAA with ENAA
As 0.03 0.001
Cs 0.04 0.005
La 0.01 0.001
Rb 1.2 0.82
Ta 0.05 0.002
Tb 0.01 0.001
Th 0.02 0.01
U 0.01 0.005
W 0.07 0.001
Zn 2.0 0.1
Irradiation time: 24 hrs 24 hrs
Cooling time: 6.2 days 0.3 days
Counting time: 120 min 80 min
Samples of the SRM NIST-613 Trace Element in
Glass were also irradiated with and without a boron
filter. In the case of bare irradiation the 1368 keV
photopeak for 24Na is still dominating (Fig. 4 upper
curve) after 53 hours decay time. Following boron-
filtered irradiation the activity of 24Na is significantly
reduced, consequently the background of the spectrum
decreases. Therefore, the analytical sensitivities are
much better for the isotopes with short half-lives (lower
curve).
To test the applicability of this technique SRM
IAEA-Soil-7 material was analyzed by ENAA, and for
comparison, parallel samples were measured by INAA.
Table 3 gives the element concentrations determined
with both techniques.
The initial sensitivity of the determination by ENAA
depends among other things on the ratio of resonance
integral to the thermal cross section, and on the levels of
the elements whose neutron induced radionuclides
produce the Compton continuum background below the
analytical peak of interest. The obtained detection
limits8 (LD) for some elements in IAEA Soil-7 reference
material measured by INAA and ENAA are presented in
Table 4.
The experimental results confirm that the accuracy
and precision of the two methods are comparable, so the
recently developed epiboron NAA can be integrated into
the routine NAA work of our laboratory.
Conclusions
If an NAA laboratory is engaged in routine analysis
of geological and biological materials, the use of
selective irradiation is unavoidable to unfold the
resulting complex spectra. Cd filters were generally used
to depress the activation of the so-called 1/v isotopes,
but several disadvantages of Cd make the method
unfeasible. In this study a large volume boron filter has
been constructed and tested. The filter is reusable and
following subsequent irradiations, no mechanical
damages have been observed so far.
The results of this study proved, that by using boron
irradiation filters significant improvements in detection
sensitivity were obtained for those (n, ) reactions having
strong and >10 eV resonances in the epithermal region.
The reliability of epiboron NAA is comparable to
conventional thermal neutron activation analysis, and
the number of the elements that can be determined
instrumentally in biological and geological materials is
considerably extended.
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