The imperative pursuit of elevated energy density in lithium primary coin cells(LPCCs)necessitates strategic architectural optimization to align with evolving market demands.A predominant approach involves the systema...The imperative pursuit of elevated energy density in lithium primary coin cells(LPCCs)necessitates strategic architectural optimization to align with evolving market demands.A predominant approach involves the systematic replacement of metallic structural support components(MSSCs)to minimize non-active constituent ratios,contingent upon maintaining robust interfacial contact integrity among electrodes,separators,and battery shells.Herein,we present a novel LPCC configuration employing solvent-free processed ultra-thick fluorinated carbon cathode(UCFxC)to achieve complete MSSCs elimination.The engineered UCFxC demonstrates exceptional areal capacity metrics(249.45 mg cm^(-2),215.77 m Ah cm^(-2)),enabling a 27.8% mass reduction compared with conventional laboratoryassembled coin cell while achieving 941.5% energy density enhancement through optimized electrode conductivity.Notably,single-walled carbon nanotube(SWCNT)-modified UCFxC architectures exhibited superior performance with energy exceeding 1.0 Wh at 50℃.This architectural paradigm provides valuable insights for developing next-generation high-energy-density LPCC systems,with practical implications for advancing miniaturized power source technologies.展开更多
Small coin cell batteries are predominantly used for testing lithium-ion batteries(LIBs)in academia because they require small amounts of material and are easy to assemble.However,insufficient attention is given to di...Small coin cell batteries are predominantly used for testing lithium-ion batteries(LIBs)in academia because they require small amounts of material and are easy to assemble.However,insufficient attention is given to difference in cell performance that arises from the differences in format between coin cells used by academic researchers and pouch or cylindrical cells which are used in industry.In this article,we compare coin cells and pouch cells of different size with exactly the same electrode materials,electrolyte,and electrochemical conditions.We show the battery impedance changes substantially depending on the cell format using techniques including Electrochemical Impedance Spectroscopy(EIS)and Galvanostatic Intermittent Titration Technique(GITT).Using full cell NCA-graphite LIBs,we demonstrate that this difference in impedance has important knock-on effects on the battery rate performance due to ohmic polarization and the battery life time due to Li metal plating on the anode.We hope this work will help researchers getting a better idea of how small coin cell formats impact the cell performance and help predicting improvements that can be achieved by implementing larger cell formats.展开更多
Non-fungible tokens(NFTs)are one-of-a-kind digital assets that are stored on a blockchain.Examples of NFTs include art(e.g.,image,video,animation),collectables(e.g.,autographs),and objects from games(e.g.,weapons and ...Non-fungible tokens(NFTs)are one-of-a-kind digital assets that are stored on a blockchain.Examples of NFTs include art(e.g.,image,video,animation),collectables(e.g.,autographs),and objects from games(e.g.,weapons and poisons).NFTs provide content creators and artists a way to promote and sell their unique digital material online.NFT coins underpin the ecosystems that support NFTs and are a new and emerging asset class and,as a new and emerging asset class,NFT coins are not immune to economic uncertainty.This research seeks to address the following questions.What is the time and frequency relationship between economic uncertainty and NFT coins?Is the relationship similar across different NFT coins?As an emerging asset,do NFT coins exhibit explosive behavior and if so,what role does economic uncertainty play in their formation?Using a new Twitter-based economic uncertainty index and a related equity market uncertainty index it is found that wavelet coherence between NFT coin prices(ENJ,MANA,THETA,XTZ)and economic uncertainty or market uncertainty is strongest during the periods January 2020 to July 2020 and January 2022 to July 2022.Periods of high significance are centered around the 64-day scale.During periods of high coherence,economic and market uncertainty exhibit an out of phase relationship with NFT coin prices.Network connectedness shows that the highest connectedness occurred during 2020 and 2022 which is consistent with the findings from wavelet analysis.Infectious disease outbreaks(COVID-19),NFT coin price volatility,and Twitter-based economic uncertainty determine bubbles in NFT coin prices.展开更多
A capacity increase is often observed in the early stage of Li-ion battery cycling.This study explores the phenomena involved in the capacity increase from the full cell,electrodes,and materials perspective through a ...A capacity increase is often observed in the early stage of Li-ion battery cycling.This study explores the phenomena involved in the capacity increase from the full cell,electrodes,and materials perspective through a combination of non-destructive diagnostic methods in a full cell and post-mortem analysis in a coin cell.The results show an increase of 1%initial capacity for the battery aged at 100%depth of discharge(DOD)and 45℃.Furthermore,large DODs or high temperatures accelerate the capacity increase.From the incremental capacity and differential voltage(IC-DV)analysis,we concluded that the increased capacity in a full cell originates from the graphite anode.Furthermore,graphite/Li coin cells show an increased capacity for larger DODs and a decreased capacity for lower DODs,thus in agreement with the full cell results.Post-mortem analysis results show that a larger DOD enlarges the graphite dspace and separates the graphite layer structure,facilitating the Li+diffusion,hence increasing the battery capacity.展开更多
Foreign body ingestion is a common emergency situation in children with one or a few objects having been ingested. Here we report our experience using endo-scopic retrieval in a female centenarian with dyspnea and for...Foreign body ingestion is a common emergency situation in children with one or a few objects having been ingested. Here we report our experience using endo-scopic retrieval in a female centenarian with dyspnea and foreign bodies in the esophagus. She attempted suicide by swallowing 26 coins and two other foreign bodies. A gastroscope was used to remove all foreign bodies in the lower esophagus. In total, 26 coins, one ferrous ring and one cylindrical plastic object were retrieved. To our knowledge, this is the first clinical report on retrieval of so many foreign bodies in a single case.展开更多
Various adaptive designs have been proposed and applied to clinical trials, bio assay, psychophysics, etc.Adaptive designs are also useful in high cost engineering trials.More and more people have been paying attentio...Various adaptive designs have been proposed and applied to clinical trials, bio assay, psychophysics, etc.Adaptive designs are also useful in high cost engineering trials.More and more people have been paying attention to these design methods. This paper introduces several broad families of designs, such as the play-the-winner rule, randomized play-the-winner rule and its generalization to the multi-arm case, doubly biased coin adaptive design, Markov chain model.展开更多
Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are h...Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are higher in the natural FeS2 than those in the treated sample. Scanning electron microscopy shows that the grain sizes of treated FeS2, particles are smaller than those of natural FeS2 particles. The electrochemical performance of Li/treated FeS2 cells is attributed to the smaller grain sizes and higher purity of treated FeS2 particles in comparison to the natural FeS2 sample.展开更多
Objective： The aim of this study was to determine an optimal slice thickness that was efficient in revealing Iobulation of malignant solitary pulmonary nodules （SPNs） on multi-slice spiral computed tomography （MSC...Objective： The aim of this study was to determine an optimal slice thickness that was efficient in revealing Iobulation of malignant solitary pulmonary nodules （SPNs） on multi-slice spiral computed tomography （MSCT） images preliminarily. Methods： Fifty patients with malignant SPNs （diameter -〈 3 cm） underwent multidetector-row computed tomography of the chest in a single-breath-hold technique. The raw data were acquired with a collimation of 0.625 mm. Three sets of contiguous images were reconstructed with 1-, 2-, and 5-ram slice thickness, respectively. The Iobulation sign of SPNs on the computed tomography （CT） images presented in 1-, 2-, and 5-ram slice thickness was compared. Using the 1-mm sections as the gold standard, an optimal slice thickness in revealing Iobulation sign of SPNs was determined. Results： The 1-mm-thick images CT revealed 98 Iobulations （25 with chord distance 〈 1 ram; 30 with chord distance 1-2 ram; 43 with chord distance 〉 2 mm） of 45 malignant SPNs. 18 Iobulations with chord distance 〈 1 mm presented in 2-mm-thick sections were as same as those in I-ram-thick sections. Statistically significant difference in Iobulations number was found between that revealed in 2-ram-thick images and that in I-ram-thick images （P = 0.023 〈 0.05）. 16 Iobulations with chord distance 〈 1 mm presented in 5-mm-thick sections were as same as that in I-ram-thick sections. There was statistically significant difference in Iobulations number between that revealed in 5-mm-thick images and that in I-ram-thick images （P = 0.004 〈 0.05）. The 24 Iobulations with chord distance 1-2 mm presented in 2-ram-thick sections were as same as that in 1-mm-thick sections. No statistically significant difference in Iobulations number were found between that revealed in 2-mm-thick images and that in 1-mm-thick images （P = 0.261 〉 0.05）. 13 Iobulations with chord distance 1-2 mm presented in 5-ram-thick sections were as same as that in 1- mm-thick sections. There was statistically significant difference in Iobulations number between that revealed in 5-ram-thick images and that in I-ram-thick images （P = 0.003 〈 0.05）. 40 Iobulations with chord distance 〉 2 mm presented in 2-ram-thick sections were as same as that in I-ram-thick sections. No statistically significant difference in Iobulations number was found between that revealed in 2-ram-thick images and that in I-ram-thick images （P = 0.631 〉 0.05）. 36 Iobulations with chord distance 〉 2 mm presented in 5-mm-thick sections were as same as that in I-ram-thick sections. There was no statistically significant difference in Iobulations number between that revealed in 5-ram-thick images and that in I-ram-thick images （P = 0.264 〉 0.05）. Conclusion： It is suggested that the use of 1-mm slice thickness is suitable in revealing Iobulations with chord distance 〈 1 ram. A 2-mm slice thickness is suggested to be used in revealing Iobulafions with chord distance 1-2 mm and 5-mm slice thickness to be used in revealing Iobulations with chord distance 〉 2 mm.展开更多
In natural environment, tarnish was observed on the surface of historic and contemporary gold coins in several countries. Few years after the emergence of panda gold coins, several red spots were appeared on the surfa...In natural environment, tarnish was observed on the surface of historic and contemporary gold coins in several countries. Few years after the emergence of panda gold coins, several red spots were appeared on the surface. To identify the stains and to examine the spots, optical microscope （OM）, scanning electron microscope （SEM）, electron microprobe analysis （EMPA）, X-ray photoelectron spectroscopy （XPS）, and X-ray diffraction （XRD） were used. It was found by microscopic observation that the stain has a dark blue central area surrounded by a large area with a nuance of colors from brown to red. Red spots usually contain holes in the center, which are distributed along the forging stress zones formed in the struck process. From the surface analyses using EMPA, sulfur and silver are detected besides gold, and the contents of Ag and S at the tarnish part are higher than those at the other part. Furthermore, distributions of Ag and S are correlated with the morphology of stains. XPS shows that components of stains are Ag2S and Ag2SO4 and the former is much predominant. These results are confirmed using XRD analysis. Accelerated tarnish test of gold in an atmosphere containing sulfur compound proves that the similar phenomenon appears when a small amount of silver is present on the surface of gold. It can be concluded that the occurrence of tarnish stains is caused by the presence of Ag and S.展开更多
A symmetric all-organic non-aqueous redox flow-type battery was investigated employing the neutral small molecule radical 3-phenyl-1,5-di-p-tolylverdazyl,which can be reversibly oxidized and reduced in one-electron pr...A symmetric all-organic non-aqueous redox flow-type battery was investigated employing the neutral small molecule radical 3-phenyl-1,5-di-p-tolylverdazyl,which can be reversibly oxidized and reduced in one-electron processes,as the sole charge storage material.Cyclic voltammetry of the verdazyl radical in 0.5 M tetrabutylammonium hexa fluoro phosphate(TBAPF6)in acetonitrile revealed redox couples at-0.17 V and-1.15 V vs.Ag+/Ag,leading to a theoretical cell voltage of 0.98 V.From the dependence of peak currents on the square root of the scan rate,diffusion coefficients on the order of 4 x 10 6 cm2 s-1 were demonstrated.Cycling performance was assessed in a static cell employing a Tokoyuma AHA anion exchange membrane,with 0.04 M verdazyl as catholyte and anolyte in 0.5 M TBAPF6 in acetonitrile at a current density of 0.12 mA cm-2.Although coulombic efficiencies were good(94%-97%)throughout the experiment,the capacity faded gradually from high initial values of 93%of the theoretical discharge capacity to 35%by the 50th cycle.Voltage and energy efficiencies were 68%and 65%,respectively.Postcycling analysis by cyclic voltammetry revealed that decomposition of the active material with cycling is a leading cause of cell degradation.展开更多
Twenty Yongzheng copper coins were fast dating by X-ray energy dispersive spectrometer with scanning electron microscope(SEM-EDS)according to official ingredient.The 20 coins were classified in two groups according to...Twenty Yongzheng copper coins were fast dating by X-ray energy dispersive spectrometer with scanning electron microscope(SEM-EDS)according to official ingredient.The 20 coins were classified in two groups according to the results.Group 1 represents the coins minted before AD 1728 and group 2 represents the coins minted after AD 1728.At concentration range(0.00%–5.13%),the distribution of lead is not homogeneous in the coins,and the largest diameter of lead inclusion is less than 15μm.The official fineness degrade is supported.展开更多
Recent literature has addressed initial coin offering(ICO)projects,which are an innovative form of venture financing through cryptocurrencies using blockchain technology.Many features of ICOs remain unexplored,leaving...Recent literature has addressed initial coin offering(ICO)projects,which are an innovative form of venture financing through cryptocurrencies using blockchain technology.Many features of ICOs remain unexplored,leaving much room for additional research,including the success factors of ICO projects.We investigate the success of ICO projects,with our main purpose being to identify factors that influence a project’s outcome.Following a literature review,from which several potential variables were collected,we used a database comprising 428 ICO projects in the banking/financial sector to regress several econometric models.We confirmed the impacts of several variables and obtained particularly valuable results concerning project and campaign variables.We confirmed the importance of a well-structured and informative white-paper.The proximity to certain markets with high availability of financial and human capital is also an important determinant of the success of an ICO.We also confirm the strong dependency on cryptocurrency and the impact of cryptocurrency valuations on the success of a project.Furthermore,we confirm the importance of social media in ICO projects,as well as the importance of human capital characteristics.Our research contributes to the ICO literature by capturing most of the success factors previously identified and testing their impacts based on a large database.The current research contributes to the building of systems theory and signaling theory by adapting their frameworks to the ICO environment.Our results are also important for regulators,as ICOs are mainly unregulated and have vast future potential,and for investors,who can benefit from our analysis and use it in their due diligence.展开更多
基金the financial support from the National Natural Science Foundation of China,Grant Nos.52307249the Natural Science Foundation of Shanghai Province,Nos.23ZR1465900+2 种基金the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission,Nos.23CGA25the Fundamental Research Funds for the Central Universities at Tongji University,Nos.PA2022000668/22120220426the Nanchang Automotive Institute of Intelligence&New Energy of Tongji University,Nos.TPD-TC202211-02。
文摘The imperative pursuit of elevated energy density in lithium primary coin cells(LPCCs)necessitates strategic architectural optimization to align with evolving market demands.A predominant approach involves the systematic replacement of metallic structural support components(MSSCs)to minimize non-active constituent ratios,contingent upon maintaining robust interfacial contact integrity among electrodes,separators,and battery shells.Herein,we present a novel LPCC configuration employing solvent-free processed ultra-thick fluorinated carbon cathode(UCFxC)to achieve complete MSSCs elimination.The engineered UCFxC demonstrates exceptional areal capacity metrics(249.45 mg cm^(-2),215.77 m Ah cm^(-2)),enabling a 27.8% mass reduction compared with conventional laboratoryassembled coin cell while achieving 941.5% energy density enhancement through optimized electrode conductivity.Notably,single-walled carbon nanotube(SWCNT)-modified UCFxC architectures exhibited superior performance with energy exceeding 1.0 Wh at 50℃.This architectural paradigm provides valuable insights for developing next-generation high-energy-density LPCC systems,with practical implications for advancing miniaturized power source technologies.
基金funding from the ERC(Consolidator Grant MIGHTY,866005)the Innovate UK(UKRI:104174)Faraday Institution-Future CAT(FIRG017)and Degradation(FIRG001)
文摘Small coin cell batteries are predominantly used for testing lithium-ion batteries(LIBs)in academia because they require small amounts of material and are easy to assemble.However,insufficient attention is given to difference in cell performance that arises from the differences in format between coin cells used by academic researchers and pouch or cylindrical cells which are used in industry.In this article,we compare coin cells and pouch cells of different size with exactly the same electrode materials,electrolyte,and electrochemical conditions.We show the battery impedance changes substantially depending on the cell format using techniques including Electrochemical Impedance Spectroscopy(EIS)and Galvanostatic Intermittent Titration Technique(GITT).Using full cell NCA-graphite LIBs,we demonstrate that this difference in impedance has important knock-on effects on the battery rate performance due to ohmic polarization and the battery life time due to Li metal plating on the anode.We hope this work will help researchers getting a better idea of how small coin cell formats impact the cell performance and help predicting improvements that can be achieved by implementing larger cell formats.
文摘Non-fungible tokens(NFTs)are one-of-a-kind digital assets that are stored on a blockchain.Examples of NFTs include art(e.g.,image,video,animation),collectables(e.g.,autographs),and objects from games(e.g.,weapons and poisons).NFTs provide content creators and artists a way to promote and sell their unique digital material online.NFT coins underpin the ecosystems that support NFTs and are a new and emerging asset class and,as a new and emerging asset class,NFT coins are not immune to economic uncertainty.This research seeks to address the following questions.What is the time and frequency relationship between economic uncertainty and NFT coins?Is the relationship similar across different NFT coins?As an emerging asset,do NFT coins exhibit explosive behavior and if so,what role does economic uncertainty play in their formation?Using a new Twitter-based economic uncertainty index and a related equity market uncertainty index it is found that wavelet coherence between NFT coin prices(ENJ,MANA,THETA,XTZ)and economic uncertainty or market uncertainty is strongest during the periods January 2020 to July 2020 and January 2022 to July 2022.Periods of high significance are centered around the 64-day scale.During periods of high coherence,economic and market uncertainty exhibit an out of phase relationship with NFT coin prices.Network connectedness shows that the highest connectedness occurred during 2020 and 2022 which is consistent with the findings from wavelet analysis.Infectious disease outbreaks(COVID-19),NFT coin price volatility,and Twitter-based economic uncertainty determine bubbles in NFT coin prices.
基金supported by a grant from the China Scholarship Council(202006370035 and 202006220024)supported by the National Natural Science Foundation of China(52107229)。
文摘A capacity increase is often observed in the early stage of Li-ion battery cycling.This study explores the phenomena involved in the capacity increase from the full cell,electrodes,and materials perspective through a combination of non-destructive diagnostic methods in a full cell and post-mortem analysis in a coin cell.The results show an increase of 1%initial capacity for the battery aged at 100%depth of discharge(DOD)and 45℃.Furthermore,large DODs or high temperatures accelerate the capacity increase.From the incremental capacity and differential voltage(IC-DV)analysis,we concluded that the increased capacity in a full cell originates from the graphite anode.Furthermore,graphite/Li coin cells show an increased capacity for larger DODs and a decreased capacity for lower DODs,thus in agreement with the full cell results.Post-mortem analysis results show that a larger DOD enlarges the graphite dspace and separates the graphite layer structure,facilitating the Li+diffusion,hence increasing the battery capacity.
文摘Foreign body ingestion is a common emergency situation in children with one or a few objects having been ingested. Here we report our experience using endo-scopic retrieval in a female centenarian with dyspnea and foreign bodies in the esophagus. She attempted suicide by swallowing 26 coins and two other foreign bodies. A gastroscope was used to remove all foreign bodies in the lower esophagus. In total, 26 coins, one ferrous ring and one cylindrical plastic object were retrieved. To our knowledge, this is the first clinical report on retrieval of so many foreign bodies in a single case.
文摘Various adaptive designs have been proposed and applied to clinical trials, bio assay, psychophysics, etc.Adaptive designs are also useful in high cost engineering trials.More and more people have been paying attention to these design methods. This paper introduces several broad families of designs, such as the play-the-winner rule, randomized play-the-winner rule and its generalization to the multi-arm case, doubly biased coin adaptive design, Markov chain model.
基金SUPPORTED BY NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA( NO. 20273047)DOCTOR FOUNDATION OF MINISTRY OF EDUCATION ( NO. 20020056045).
文摘Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are higher in the natural FeS2 than those in the treated sample. Scanning electron microscopy shows that the grain sizes of treated FeS2, particles are smaller than those of natural FeS2 particles. The electrochemical performance of Li/treated FeS2 cells is attributed to the smaller grain sizes and higher purity of treated FeS2 particles in comparison to the natural FeS2 sample.
文摘Objective： The aim of this study was to determine an optimal slice thickness that was efficient in revealing Iobulation of malignant solitary pulmonary nodules （SPNs） on multi-slice spiral computed tomography （MSCT） images preliminarily. Methods： Fifty patients with malignant SPNs （diameter -〈 3 cm） underwent multidetector-row computed tomography of the chest in a single-breath-hold technique. The raw data were acquired with a collimation of 0.625 mm. Three sets of contiguous images were reconstructed with 1-, 2-, and 5-ram slice thickness, respectively. The Iobulation sign of SPNs on the computed tomography （CT） images presented in 1-, 2-, and 5-ram slice thickness was compared. Using the 1-mm sections as the gold standard, an optimal slice thickness in revealing Iobulation sign of SPNs was determined. Results： The 1-mm-thick images CT revealed 98 Iobulations （25 with chord distance 〈 1 ram; 30 with chord distance 1-2 ram; 43 with chord distance 〉 2 mm） of 45 malignant SPNs. 18 Iobulations with chord distance 〈 1 mm presented in 2-mm-thick sections were as same as those in I-ram-thick sections. Statistically significant difference in Iobulations number was found between that revealed in 2-ram-thick images and that in I-ram-thick images （P = 0.023 〈 0.05）. 16 Iobulations with chord distance 〈 1 mm presented in 5-mm-thick sections were as same as that in I-ram-thick sections. There was statistically significant difference in Iobulations number between that revealed in 5-mm-thick images and that in I-ram-thick images （P = 0.004 〈 0.05）. The 24 Iobulations with chord distance 1-2 mm presented in 2-ram-thick sections were as same as that in 1-mm-thick sections. No statistically significant difference in Iobulations number were found between that revealed in 2-mm-thick images and that in 1-mm-thick images （P = 0.261 〉 0.05）. 13 Iobulations with chord distance 1-2 mm presented in 5-ram-thick sections were as same as that in 1- mm-thick sections. There was statistically significant difference in Iobulations number between that revealed in 5-ram-thick images and that in I-ram-thick images （P = 0.003 〈 0.05）. 40 Iobulations with chord distance 〉 2 mm presented in 2-ram-thick sections were as same as that in I-ram-thick sections. No statistically significant difference in Iobulations number was found between that revealed in 2-ram-thick images and that in I-ram-thick images （P = 0.631 〉 0.05）. 36 Iobulations with chord distance 〉 2 mm presented in 5-mm-thick sections were as same as that in I-ram-thick sections. There was no statistically significant difference in Iobulations number between that revealed in 5-ram-thick images and that in I-ram-thick images （P = 0.264 〉 0.05）. Conclusion： It is suggested that the use of 1-mm slice thickness is suitable in revealing Iobulations with chord distance 〈 1 ram. A 2-mm slice thickness is suggested to be used in revealing Iobulafions with chord distance 1-2 mm and 5-mm slice thickness to be used in revealing Iobulations with chord distance 〉 2 mm.
文摘In natural environment, tarnish was observed on the surface of historic and contemporary gold coins in several countries. Few years after the emergence of panda gold coins, several red spots were appeared on the surface. To identify the stains and to examine the spots, optical microscope （OM）, scanning electron microscope （SEM）, electron microprobe analysis （EMPA）, X-ray photoelectron spectroscopy （XPS）, and X-ray diffraction （XRD） were used. It was found by microscopic observation that the stain has a dark blue central area surrounded by a large area with a nuance of colors from brown to red. Red spots usually contain holes in the center, which are distributed along the forging stress zones formed in the struck process. From the surface analyses using EMPA, sulfur and silver are detected besides gold, and the contents of Ag and S at the tarnish part are higher than those at the other part. Furthermore, distributions of Ag and S are correlated with the morphology of stains. XPS shows that components of stains are Ag2S and Ag2SO4 and the former is much predominant. These results are confirmed using XRD analysis. Accelerated tarnish test of gold in an atmosphere containing sulfur compound proves that the similar phenomenon appears when a small amount of silver is present on the surface of gold. It can be concluded that the occurrence of tarnish stains is caused by the presence of Ag and S.
基金supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada (C. A. D.: DG, 04279 J. B. G.: DG, 435675 and S. M. B.: CGS D scholarship)+1 种基金support form the Canada Foundation for Innovation (CFI) the New Brunswick Innovation Foundation (NBIF)the University of New Brunswick. J. B. G. would like to thank the University of Western Ontario for support
文摘A symmetric all-organic non-aqueous redox flow-type battery was investigated employing the neutral small molecule radical 3-phenyl-1,5-di-p-tolylverdazyl,which can be reversibly oxidized and reduced in one-electron processes,as the sole charge storage material.Cyclic voltammetry of the verdazyl radical in 0.5 M tetrabutylammonium hexa fluoro phosphate(TBAPF6)in acetonitrile revealed redox couples at-0.17 V and-1.15 V vs.Ag+/Ag,leading to a theoretical cell voltage of 0.98 V.From the dependence of peak currents on the square root of the scan rate,diffusion coefficients on the order of 4 x 10 6 cm2 s-1 were demonstrated.Cycling performance was assessed in a static cell employing a Tokoyuma AHA anion exchange membrane,with 0.04 M verdazyl as catholyte and anolyte in 0.5 M TBAPF6 in acetonitrile at a current density of 0.12 mA cm-2.Although coulombic efficiencies were good(94%-97%)throughout the experiment,the capacity faded gradually from high initial values of 93%of the theoretical discharge capacity to 35%by the 50th cycle.Voltage and energy efficiencies were 68%and 65%,respectively.Postcycling analysis by cyclic voltammetry revealed that decomposition of the active material with cycling is a leading cause of cell degradation.
基金Supported by the Project of Instrument Upgraded of Ministry of Science and Technology of China
文摘Twenty Yongzheng copper coins were fast dating by X-ray energy dispersive spectrometer with scanning electron microscope(SEM-EDS)according to official ingredient.The 20 coins were classified in two groups according to the results.Group 1 represents the coins minted before AD 1728 and group 2 represents the coins minted after AD 1728.At concentration range(0.00%–5.13%),the distribution of lead is not homogeneous in the coins,and the largest diameter of lead inclusion is less than 15μm.The official fineness degrade is supported.
基金supported by Fundação para a Ciência e a Tecnologia,grant UIDB/00315/2020.
文摘Recent literature has addressed initial coin offering(ICO)projects,which are an innovative form of venture financing through cryptocurrencies using blockchain technology.Many features of ICOs remain unexplored,leaving much room for additional research,including the success factors of ICO projects.We investigate the success of ICO projects,with our main purpose being to identify factors that influence a project’s outcome.Following a literature review,from which several potential variables were collected,we used a database comprising 428 ICO projects in the banking/financial sector to regress several econometric models.We confirmed the impacts of several variables and obtained particularly valuable results concerning project and campaign variables.We confirmed the importance of a well-structured and informative white-paper.The proximity to certain markets with high availability of financial and human capital is also an important determinant of the success of an ICO.We also confirm the strong dependency on cryptocurrency and the impact of cryptocurrency valuations on the success of a project.Furthermore,we confirm the importance of social media in ICO projects,as well as the importance of human capital characteristics.Our research contributes to the ICO literature by capturing most of the success factors previously identified and testing their impacts based on a large database.The current research contributes to the building of systems theory and signaling theory by adapting their frameworks to the ICO environment.Our results are also important for regulators,as ICOs are mainly unregulated and have vast future potential,and for investors,who can benefit from our analysis and use it in their due diligence.
