The 8th China-Africa Youth Festival was a precious opportunity to not only learn about Chinese culture but also to explore the rich tapestry of cultures of different African countries.Participants had the chance to ta...The 8th China-Africa Youth Festival was a precious opportunity to not only learn about Chinese culture but also to explore the rich tapestry of cultures of different African countries.Participants had the chance to talk to young leaders from across the continent,fostering new bonds and connections that can potentially benefit everyone involved in the future.This cultural exchange not only broadened our understanding but also paved the way for collaboration and enduring friendships that could be good for personal development.展开更多
Commodity markets,such as crude oil and precious metals,play a strategic role in the economic development of nations,with crude oil prices influencing geopolitical relations and the global economy.Moreover,gold and si...Commodity markets,such as crude oil and precious metals,play a strategic role in the economic development of nations,with crude oil prices influencing geopolitical relations and the global economy.Moreover,gold and silver are argued to hedge the stock and cryptocurrency markets during market downsides.Therefore,accurate forecasting of crude oil and precious metals prices is critical.Nevertheless,due to the nonlinear nature,substantial fluctuations,and irregular cycles of crude oil and precious metals,predicting their prices is a challenging task.Our study contributes to the commodity market price forecasting literature by implementing and comparing advanced deep-learning models.We address this gap by including silver alongside gold in our analysis,offering a more comprehensive understanding of the precious metal markets.This research expands existing knowledge and provides valuable insights into predicting commodity prices.In this study,we implemented 16 deep-and machine-learning models to forecast the daily price of the West Texas Intermediate(WTI),Brent,gold,and silver markets.The employed deep-learning models are long short-term memory(LSTM),BiLSTM,gated recurrent unit(GRU),bidirectional gated recurrent units(BiGRU),T2V-BiLSTM,T2V-BiGRU,convolutional neural networks(CNN),CNN-BiLSTM,CNN-BiGRU,temporal convolutional network(TCN),TCN-BiLSTM,and TCN-BiGRU.We compared the forecasting performance of deep-learning models with the baseline random forest,LightGBM,support vector regression,and k-nearest neighborhood models using mean absolute error(MAE),mean absolute percentage error,and root mean squared error as evaluation criteria.By considering different sliding window lengths,we examine the forecasting performance of our models.Our results reveal that the TCN model outperforms the others for WTI,Brent,and silver,achieving the lowest MAE values of 1.444,1.295,and 0.346,respectively.The BiGRU model performs best for gold,with an MAE of 15.188 using a 30-day input sequence.Furthermore,LightGBM exhibits comparable performance to TCN and is the best-performing machine-learning model overall.These findings are critical for investors,policymakers,mining companies,and governmental agencies to effectively anticipate market trends,mitigate risk,manage uncertainty,and make timely decisions and strategies regarding crude oil,gold,and silver markets.展开更多
From the perspective of long-term and short-term, the methods of TY causality test, generalized impulse response function, variance decomposition were used to investigate the impacts of international oil prices and ma...From the perspective of long-term and short-term, the methods of TY causality test, generalized impulse response function, variance decomposition were used to investigate the impacts of international oil prices and macroeconomic variables on Chinese gold, silver and platinum prices, but also the feedback effects of Chinese precious metal prices under this impact. The results show that international oil prices play an important role in precious metal price variation both in long-term and short-term, and exchange rate only has an effect in short-term, while interest rate is ineffective in predicting precious metal prices. In addition, precious metal prices have some feedback effects on international oil prices and interest rate in short-term.展开更多
Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of...Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of the formation in the Dachengzi, Chaoyang, Dapingfang.Meileyingzi and Fuxin-Yixian basins. Among them, the precious fossil-bearing beds in the Dachengzi Basin may be recognized as the Xidagou Bed of the second member and the Yangcaogoudonggou Bed of the third member; those in the Chaoyang Basin may be confirmed as the Shangheshou Bed of the second member and the Dongpochi Bed of the third member; those in the Dapingfang-Meileyingzi Basin are as the Lamagou Bed of the second member, the Huanghuagou Bed of the lower third member and the Yuanjiawa Bed of the upper third member; and those in the Fuxin-Yixian Basin are listed as the Tuanshanzi Bed of the second member and the Pijiagou Bed of the third member. Since these basins are distinctly separated and the bird and reptile fossils are mostly new genera and species, we have to use the associated fossil ostracod assemblages as index to correlate the Xidagou Bed with the Shangheshou Bed and the Lamagou Bed, and to correlate the Yuanjiawa Bed with the Yangcaogoudonggou Bed and the Pijiagou Bed. Primarily, we established the sequence of the precious fossil-bearing beds of the Jiufotang Formation in western Liaoning. They are represented by, in ascending order, the Xidagou Bed of the second member, the Huanghuagou Bed of the lower third member, and the Yuanjiawa Bed of the upper third member. Obviously, this work has significance for the study on the time-space distribution and radiation of birds and dinosaurs during the period of the middle Early Cretaceous.展开更多
As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with hig...As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains challenging.Herein,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive characterizations.More importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen evolution.Especially for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.展开更多
The recovery of precious metals from the secondary resources by microwave technology has emerged in recent years. Microwave technology as a new method for the recovery of precious metals has shown significant advantag...The recovery of precious metals from the secondary resources by microwave technology has emerged in recent years. Microwave technology as a new method for the recovery of precious metals has shown significant advantages against the conventional recovery procedures. This paper presents a review of the advances in microwave technology applied to the recovery of precious metals from the secondary resources. Many different applications are considered, including microwave-assisted leaching, microwave augmented ashing and microwave pyrolysis. In general, microwave enhanced recovery of precious metals from secondary resources.展开更多
Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders （MAPR） attached to...Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders （MAPR） attached to a towed deep-sea instrument was used to search for hydrothermal plumes and hydrothermal vents. We introduced the basic principle of MAPR based on deep towing technology to detect plumes, then analyzed the factors affecting the quality of the MAPR data and presented a data correction method for MAPR, including instrument location correction, noise reduction processing, system error elimination and seawater background reduction. Finally we applied the method to analyze MAPR data obtained during the Chinese DY115-21 cruise on R/VDayang Iin the “Precious Stone Mountain” hydrothermal field on the Gala-pagos Microplate. The results provided a better understanding of the distribution of the hydrothermal activ-ity in this field, indicating the presence of a new hydrothermal vent.展开更多
A new technique of swelling oxidizing roasting and alkaline leaching was proposed for deselenization and detellurization of pre- cious-metal ore concentrates. Alkali-metal and alkaline-earth-metal chlorides and carbon...A new technique of swelling oxidizing roasting and alkaline leaching was proposed for deselenization and detellurization of pre- cious-metal ore concentrates. Alkali-metal and alkaline-earth-metal chlorides and carbonates were preliminarily selected as swelling agents. The roasting removal rate and alkaline leaching rate of selenium and tellurium were investigated, and NaCl was selected as an appropriate swelling agent. Furthermore, the effects of various factors on the selenium gasification rate and leaching rate of selenium and tellurium were investigated. The results show that the selenium gasification rate reaches 88.41% after swelling oxidizing roasting for 2 h at 510~C using an NaC1 dosage coefficient of 100 and a sulfuric acid dosage coefficient of 1.3; the amorphous elemental tellurium is completely transformed into TeO2. The roasted product is subjected to alkaline leaching using a 100 g/L NaOH solution, which results in a selenium leaching rate of 10.51%, a total selenium removal rate of 98.92%, and a tellurium leaching rate of 97.64%. In the alkaline leaching residue, the contents of selenium, tellurium, gold, platinum, and palladium are 0.7825%, 5.492%, 8.333%, 0.2587%, and 1.113%, respectively; the precious metals are enriched approximately sixfold.展开更多
The Jianchang Basin is one of the main localities of the precious fossils of Jehol Biota in western Liaoning.The fossil-bearing horizons are mainly in the Yixian-and Jiufotang formations.In the Weijialing--Yaolugou of...The Jianchang Basin is one of the main localities of the precious fossils of Jehol Biota in western Liaoning.The fossil-bearing horizons are mainly in the Yixian-and Jiufotang formations.In the Weijialing--Yaolugou of southwest Jianchang Basin,many precious fossils have been found at Luojiagou Bed of the 2nd Member of the Yixian Formation and at Xidian Bed of the 1st member of the Jiufotang Formation.The geologic setting,sedimentary environment and paleogeography of the precious fossil-bearing beds were also studied.展开更多
With the increasing awareness of environmental protection, people’s concern of pollution issues arising. Vehicles, as the most important means of transportation, its exhaust emission has received considerable attenti...With the increasing awareness of environmental protection, people’s concern of pollution issues arising. Vehicles, as the most important means of transportation, its exhaust emission has received considerable attention. The catalytic converter is able to purify harmful substances in exhaust gas. The absolute content of precious metals in the catalytic converter dominates the exhaust gas purification effect. Accurate detection of precious metal content is of great significance for controlling the cost of catalysts, ensuring catalytic performance and recovering precious metals from spent catalysts. We herein summarized several instruments for precious metals content exploration, such as X-ray fluorescence spectrometer (XRF), atomic absorption spectrometer (AAS), inductively coupled plasma emission spectrometer (ICP) and spectrophotometer. In this thesis, the feasibility of using various devices for characterizing precious metal content in catalytic converters is analyzed and their strengths or weaknesses are elaborated.展开更多
Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and pu...Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and purification. Using fragmentation technology realizes fast dissolution of palladium, silver, copper and zinc in the wastes, and high efficient and complete separation of them from gold and platinum; using evaporation thermal decomposition technology of mixed solution produced by nitric acid dissolving palladium, silver, copper and zinc, complete and high efficient separation of silver from palladium was realized; by control of solution acidity, using hydrazine reduction method, high efficient and complete separation of gold from platinum was realized. Using this new technology, the recovery rates of palladium and silver are above 99%, and gold and platinum above 98%, the grade of pure metals are above 99.95%.展开更多
Situated in Kunming,Yunnan Province,the institute is a scientific research organiza-tion with a history of fifty years.It is nowaffiliated with the China National NonferrousMetals Industry Corporation.At the beginning...Situated in Kunming,Yunnan Province,the institute is a scientific research organiza-tion with a history of fifty years.It is nowaffiliated with the China National NonferrousMetals Industry Corporation.At the beginning of the nineteen sixties,the institute commenced research workin the field of precious metals.It has sincethen developed and extended greatly,andits activities now cover various fields ofprecious metals science and technology,including the comprehensive utilization展开更多
This study reveals the time-varying spillover effects of higher moments(realized volatility,realized skewness and realized kurtosis)and jumps between China’s precious metals and industrial metals markets.Using 5-min ...This study reveals the time-varying spillover effects of higher moments(realized volatility,realized skewness and realized kurtosis)and jumps between China’s precious metals and industrial metals markets.Using 5-min high-frequency data from May 10,2012 to October 21,2021,the dynamic effects of spillovers are uncovered using the time-frequency domain spillover index framework.The results show that the system connectedness weakens as the moment order gets higher whereas the total jumps connectedness is the smallest,and the spillovers of all estimators are more evident in the short term.The overall information spillovers are time-varying and influenced by major market events.Specifically,for realized volatility,copper is the largest net transmitter and silver is always a net transmitter,while zinc is the largest net receiver.For realized skewness,copper is the largest net transmitter and silver is always a net transmitter,while lead is the largest net receiver.For realized kurtosis and jumps,copper is the largest net transmitter,while aluminum is the largest net receiver.Overall,copper and silver play dominant roles in China’s precious and industrial metals markets system.展开更多
On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from s...On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from secondary resources of low-grade metals by adding iron oxide as the trapping agent, reducing agent, additive, mixing uniformly and grinding, pelletizing, reduction, grinding and separation, and selectively acid leaching iron has been put forward in this paper. The experiments of reduction, grinding and separation, and selectively acid leaching iron were carried out mainly. Under the decided experiment parameters and conditions, iron generated during the reduction can trap precious metals during reduction, high active alloy powders were obtained from the reduced products by grinding and separation, the concentration of precious metals was obtained by acid leaching high active alloy powders. The better enrichment effect was obtained by adopting the technical route of processing. Other low grade noble metal materials and enrichment ratio of precious metals from the materials to acid products was high through acid leaching. This process has the advantages of simple process, environmental-friendly, strong adaptability of raw materials, high concentration ratio, which was regarded as a kind of the general efficient enrichment technology of low grade precious metal materials.展开更多
A survey about OJSC "SIC Supermetal'" as a processor of secondary precious metal raw materials and a manufacturer of precious metal products for technical purposes,has been presented.Brief information ha...A survey about OJSC "SIC Supermetal'" as a processor of secondary precious metal raw materials and a manufacturer of precious metal products for technical purposes,has been presented.Brief information has been given about the basic technologies and materials used in production,including dispersion strengthened materials on the basis of platinum alloys and laminar composites.展开更多
The activities of ZrO_2-supported precious metal catalysts for simultaneous removal of soot and NO_x in the presence of rich O_2and H_2O as well as SO_2 have been studied by keeping loose contact between catalyst and ...The activities of ZrO_2-supported precious metal catalysts for simultaneous removal of soot and NO_x in the presence of rich O_2and H_2O as well as SO_2 have been studied by keeping loose contact between catalyst and soot.The results show that only Ru,Ir and Rh have catalytic activity for simultaneous removal of soot and NO_x and the order of catalytic activity is Ru > Ir > Rh.Pt has the catalytic activity only for the removal of soot,and Ag,Pd,and Au have hardly any catalytic activities for the removal of soot and NO_x.The relationships between catalytic activity of precious metal catalysts and various reaction conditions were discussed.展开更多
This study examines the role of market sentiment in predicting the price bubbles of four strategic metal commodities(gold,silver,palladium,and platinum)from January 1985 to August 2020.It is the first to investigate t...This study examines the role of market sentiment in predicting the price bubbles of four strategic metal commodities(gold,silver,palladium,and platinum)from January 1985 to August 2020.It is the first to investigate this topic using sentiment indices,including news-based economic and consumer-based sentiments developed using different methods.We observed the role of sentiment as a reliable indicator of future bubbles for some metal commodities and found that bubbles were regularly concomi-tant with bearish sentiments for gold and platinum.Moreover,gold and palladium were the only commodities that experienced a bubble during the COVID-19 pandemic.Overall,our findings suggest inclusion of sentiment to the model that predicts the price bubbles of precious metals.展开更多
The region of existence of phases in equilibrium with the solid solution based on palladium. Presented to analyze the current situation in the market of precious metals in Russia. Provides information about the produc...The region of existence of phases in equilibrium with the solid solution based on palladium. Presented to analyze the current situation in the market of precious metals in Russia. Provides information about the production and processing of precious metals. Prospects for the most likely path of development of the Russian market of precious metals.展开更多
In June 2012,the UN conference on sustainable development "Rio+20" summarized the work of the world community in this direction for last 20 years and outlined the tasks for the future.The UN website contains...In June 2012,the UN conference on sustainable development "Rio+20" summarized the work of the world community in this direction for last 20 years and outlined the tasks for the future.The UN website contains enough information to estimate the importance of global problems and "green economy," taking into account a very complicated state of the global and Russian markets which are balancing on the verge of crisis.Unfortunately,the website does not contain the materials of the 6th civilization forum "Long-Term Strategy for Sustainable Development on the Basis of Partnership of Civilizations:Concepts,Strategy,Programs and Projects" within the bounds of "Rio+20" which has considered the problems of a dialogue and partnership in conditions of extensive globalization.These problems are covered in the Partnership of Civilizations Journal which is issued in the Russian,English and Arabian languages,including its Internet version.The International Informatization Academy (it has the general consultative status at the Economic and Social Council of the UN) and its 20-year activity in the sphere of informatization of the world and Russia on the way to the partnership of civilizations,are presented there[1].展开更多
Precious metals are highly demanded economic value metals that require to be recovered from industrial wastes and electronic used products (e-waste). They are such as gold (Au) as well as Platinum Group Metals (PGMs) ...Precious metals are highly demanded economic value metals that require to be recovered from industrial wastes and electronic used products (e-waste). They are such as gold (Au) as well as Platinum Group Metals (PGMs) for instance palladium (Pd) and platinum (Pt). The study was conducted to test the magnetic iron oxide nanoparticles modified with Moringa oleifera seed proteins as adsorbent for recovery of Au(III), Pd(II) and Pt(IV) from aqueous solutions. Different functional groups responsible for adsorption, morphology, thermal stability, and surface charges of the nanoparticles were characterized with FTIR, SEM, TGA and Zeta potential respectively. Batch adsorption method was used, and precious metal ions percentage recovery was measured using ICP-OES. The effects of pH, initial adsorbate concentration, adsorption agitation time and adsorbent dosage were studied at room temperature of 25°C. Au(III) yielded a maximal recovery of 99.8%, followed by Pt(IV) with 87.7%, then Pd(II) with 72.7% at a pH 2.5, 10 mg/L initial adsorbate concentration, 120 minutes agitation time and 0.065 g adsorbent dosage. These results suggested that modified iron oxide nanoparticles were effective in selective recovery of the precious metal ions.展开更多
文摘The 8th China-Africa Youth Festival was a precious opportunity to not only learn about Chinese culture but also to explore the rich tapestry of cultures of different African countries.Participants had the chance to talk to young leaders from across the continent,fostering new bonds and connections that can potentially benefit everyone involved in the future.This cultural exchange not only broadened our understanding but also paved the way for collaboration and enduring friendships that could be good for personal development.
文摘Commodity markets,such as crude oil and precious metals,play a strategic role in the economic development of nations,with crude oil prices influencing geopolitical relations and the global economy.Moreover,gold and silver are argued to hedge the stock and cryptocurrency markets during market downsides.Therefore,accurate forecasting of crude oil and precious metals prices is critical.Nevertheless,due to the nonlinear nature,substantial fluctuations,and irregular cycles of crude oil and precious metals,predicting their prices is a challenging task.Our study contributes to the commodity market price forecasting literature by implementing and comparing advanced deep-learning models.We address this gap by including silver alongside gold in our analysis,offering a more comprehensive understanding of the precious metal markets.This research expands existing knowledge and provides valuable insights into predicting commodity prices.In this study,we implemented 16 deep-and machine-learning models to forecast the daily price of the West Texas Intermediate(WTI),Brent,gold,and silver markets.The employed deep-learning models are long short-term memory(LSTM),BiLSTM,gated recurrent unit(GRU),bidirectional gated recurrent units(BiGRU),T2V-BiLSTM,T2V-BiGRU,convolutional neural networks(CNN),CNN-BiLSTM,CNN-BiGRU,temporal convolutional network(TCN),TCN-BiLSTM,and TCN-BiGRU.We compared the forecasting performance of deep-learning models with the baseline random forest,LightGBM,support vector regression,and k-nearest neighborhood models using mean absolute error(MAE),mean absolute percentage error,and root mean squared error as evaluation criteria.By considering different sliding window lengths,we examine the forecasting performance of our models.Our results reveal that the TCN model outperforms the others for WTI,Brent,and silver,achieving the lowest MAE values of 1.444,1.295,and 0.346,respectively.The BiGRU model performs best for gold,with an MAE of 15.188 using a 30-day input sequence.Furthermore,LightGBM exhibits comparable performance to TCN and is the best-performing machine-learning model overall.These findings are critical for investors,policymakers,mining companies,and governmental agencies to effectively anticipate market trends,mitigate risk,manage uncertainty,and make timely decisions and strategies regarding crude oil,gold,and silver markets.
基金Project(13&ZD169)supported by the Major Program of the National Social Science Foundation,ChinaProject(13YJAZH149)supported by Research Project in Humanities and Social Sciences Conducted by the Ministry of Education,China+2 种基金Project(2011ZK2043)supported by the Key Program of the Soft Science Research Project of Hunan Province,ChinaProject(2015JJ2182)supported by Natural Science Foundation of Hunan Province of ChinaProject(2009JYJR035)supported by Emergency Project "The Study of International Financial Crisis" of Ministry of Education of China
文摘From the perspective of long-term and short-term, the methods of TY causality test, generalized impulse response function, variance decomposition were used to investigate the impacts of international oil prices and macroeconomic variables on Chinese gold, silver and platinum prices, but also the feedback effects of Chinese precious metal prices under this impact. The results show that international oil prices play an important role in precious metal price variation both in long-term and short-term, and exchange rate only has an effect in short-term, while interest rate is ineffective in predicting precious metal prices. In addition, precious metal prices have some feedback effects on international oil prices and interest rate in short-term.
文摘Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of the formation in the Dachengzi, Chaoyang, Dapingfang.Meileyingzi and Fuxin-Yixian basins. Among them, the precious fossil-bearing beds in the Dachengzi Basin may be recognized as the Xidagou Bed of the second member and the Yangcaogoudonggou Bed of the third member; those in the Chaoyang Basin may be confirmed as the Shangheshou Bed of the second member and the Dongpochi Bed of the third member; those in the Dapingfang-Meileyingzi Basin are as the Lamagou Bed of the second member, the Huanghuagou Bed of the lower third member and the Yuanjiawa Bed of the upper third member; and those in the Fuxin-Yixian Basin are listed as the Tuanshanzi Bed of the second member and the Pijiagou Bed of the third member. Since these basins are distinctly separated and the bird and reptile fossils are mostly new genera and species, we have to use the associated fossil ostracod assemblages as index to correlate the Xidagou Bed with the Shangheshou Bed and the Lamagou Bed, and to correlate the Yuanjiawa Bed with the Yangcaogoudonggou Bed and the Pijiagou Bed. Primarily, we established the sequence of the precious fossil-bearing beds of the Jiufotang Formation in western Liaoning. They are represented by, in ascending order, the Xidagou Bed of the second member, the Huanghuagou Bed of the lower third member, and the Yuanjiawa Bed of the upper third member. Obviously, this work has significance for the study on the time-space distribution and radiation of birds and dinosaurs during the period of the middle Early Cretaceous.
基金National Natural Science Foundation of China,Grant/Award Numbers:62105083,22109034,22109035,52164028Start-up Research Foundation of Hainan University,Grant/Award Numbers:KYQD(ZR)-20008,KYQD(ZR)-20082,KYQD(ZR)-20083,KYQD(ZR)-20084,KYQD(ZR)-21065,KYQD(ZR)-21124,KYQD(ZR)-21125+4 种基金Basic and Applied Basic Research Foundation of Guangdong Province,Grant/Award Number:2019A1515110558Hainan Provincial Postdoctoral Science Foundation,Grant/Award Number:RZ2100007123Hainan Province Science and Technology Special Fund,Grant/Award Numbers:ZDYF2020037,ZDYF2020207Hainan Provincial Natural Science Foundation,Grant/Award Numbers:222MS009,222RC548The specific research fund of The Innovation Platform for Academicians of Hainan Province。
文摘As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains challenging.Herein,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive characterizations.More importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen evolution.Especially for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.
文摘The recovery of precious metals from the secondary resources by microwave technology has emerged in recent years. Microwave technology as a new method for the recovery of precious metals has shown significant advantages against the conventional recovery procedures. This paper presents a review of the advances in microwave technology applied to the recovery of precious metals from the secondary resources. Many different applications are considered, including microwave-assisted leaching, microwave augmented ashing and microwave pyrolysis. In general, microwave enhanced recovery of precious metals from secondary resources.
基金The National Basic Research Program of China(973 Program)under contract No.2012CB417305China Ocean Mineral Resources R&D Association"Twelfth Five-Year"Major Program under contract Nos DY125-11-R-01 and DY125-11-R-05+1 种基金the Natural Science Foundation of Zhejiang Province under contract No.LY12D06006the scientific research fund of the Second Institute of Oceanography under contract No.JG1203
文摘Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders （MAPR） attached to a towed deep-sea instrument was used to search for hydrothermal plumes and hydrothermal vents. We introduced the basic principle of MAPR based on deep towing technology to detect plumes, then analyzed the factors affecting the quality of the MAPR data and presented a data correction method for MAPR, including instrument location correction, noise reduction processing, system error elimination and seawater background reduction. Finally we applied the method to analyze MAPR data obtained during the Chinese DY115-21 cruise on R/VDayang Iin the “Precious Stone Mountain” hydrothermal field on the Gala-pagos Microplate. The results provided a better understanding of the distribution of the hydrothermal activ-ity in this field, indicating the presence of a new hydrothermal vent.
文摘A new technique of swelling oxidizing roasting and alkaline leaching was proposed for deselenization and detellurization of pre- cious-metal ore concentrates. Alkali-metal and alkaline-earth-metal chlorides and carbonates were preliminarily selected as swelling agents. The roasting removal rate and alkaline leaching rate of selenium and tellurium were investigated, and NaCl was selected as an appropriate swelling agent. Furthermore, the effects of various factors on the selenium gasification rate and leaching rate of selenium and tellurium were investigated. The results show that the selenium gasification rate reaches 88.41% after swelling oxidizing roasting for 2 h at 510~C using an NaC1 dosage coefficient of 100 and a sulfuric acid dosage coefficient of 1.3; the amorphous elemental tellurium is completely transformed into TeO2. The roasted product is subjected to alkaline leaching using a 100 g/L NaOH solution, which results in a selenium leaching rate of 10.51%, a total selenium removal rate of 98.92%, and a tellurium leaching rate of 97.64%. In the alkaline leaching residue, the contents of selenium, tellurium, gold, platinum, and palladium are 0.7825%, 5.492%, 8.333%, 0.2587%, and 1.113%, respectively; the precious metals are enriched approximately sixfold.
基金Supported by Projects of the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(No.GPMR200603)Project of Education Bureau of Liaoning Province(No.20060805)
文摘The Jianchang Basin is one of the main localities of the precious fossils of Jehol Biota in western Liaoning.The fossil-bearing horizons are mainly in the Yixian-and Jiufotang formations.In the Weijialing--Yaolugou of southwest Jianchang Basin,many precious fossils have been found at Luojiagou Bed of the 2nd Member of the Yixian Formation and at Xidian Bed of the 1st member of the Jiufotang Formation.The geologic setting,sedimentary environment and paleogeography of the precious fossil-bearing beds were also studied.
文摘With the increasing awareness of environmental protection, people’s concern of pollution issues arising. Vehicles, as the most important means of transportation, its exhaust emission has received considerable attention. The catalytic converter is able to purify harmful substances in exhaust gas. The absolute content of precious metals in the catalytic converter dominates the exhaust gas purification effect. Accurate detection of precious metal content is of great significance for controlling the cost of catalysts, ensuring catalytic performance and recovering precious metals from spent catalysts. We herein summarized several instruments for precious metals content exploration, such as X-ray fluorescence spectrometer (XRF), atomic absorption spectrometer (AAS), inductively coupled plasma emission spectrometer (ICP) and spectrophotometer. In this thesis, the feasibility of using various devices for characterizing precious metal content in catalytic converters is analyzed and their strengths or weaknesses are elaborated.
文摘Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and purification. Using fragmentation technology realizes fast dissolution of palladium, silver, copper and zinc in the wastes, and high efficient and complete separation of them from gold and platinum; using evaporation thermal decomposition technology of mixed solution produced by nitric acid dissolving palladium, silver, copper and zinc, complete and high efficient separation of silver from palladium was realized; by control of solution acidity, using hydrazine reduction method, high efficient and complete separation of gold from platinum was realized. Using this new technology, the recovery rates of palladium and silver are above 99%, and gold and platinum above 98%, the grade of pure metals are above 99.95%.
文摘Situated in Kunming,Yunnan Province,the institute is a scientific research organiza-tion with a history of fifty years.It is nowaffiliated with the China National NonferrousMetals Industry Corporation.At the beginning of the nineteen sixties,the institute commenced research workin the field of precious metals.It has sincethen developed and extended greatly,andits activities now cover various fields ofprecious metals science and technology,including the comprehensive utilization
基金the financial support from the National Natural Science Foundation of China(No.72172107)。
文摘This study reveals the time-varying spillover effects of higher moments(realized volatility,realized skewness and realized kurtosis)and jumps between China’s precious metals and industrial metals markets.Using 5-min high-frequency data from May 10,2012 to October 21,2021,the dynamic effects of spillovers are uncovered using the time-frequency domain spillover index framework.The results show that the system connectedness weakens as the moment order gets higher whereas the total jumps connectedness is the smallest,and the spillovers of all estimators are more evident in the short term.The overall information spillovers are time-varying and influenced by major market events.Specifically,for realized volatility,copper is the largest net transmitter and silver is always a net transmitter,while zinc is the largest net receiver.For realized skewness,copper is the largest net transmitter and silver is always a net transmitter,while lead is the largest net receiver.For realized kurtosis and jumps,copper is the largest net transmitter,while aluminum is the largest net receiver.Overall,copper and silver play dominant roles in China’s precious and industrial metals markets system.
基金The National Basic Research Program( 973 Plan) of China(2012CB724201)
文摘On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from secondary resources of low-grade metals by adding iron oxide as the trapping agent, reducing agent, additive, mixing uniformly and grinding, pelletizing, reduction, grinding and separation, and selectively acid leaching iron has been put forward in this paper. The experiments of reduction, grinding and separation, and selectively acid leaching iron were carried out mainly. Under the decided experiment parameters and conditions, iron generated during the reduction can trap precious metals during reduction, high active alloy powders were obtained from the reduced products by grinding and separation, the concentration of precious metals was obtained by acid leaching high active alloy powders. The better enrichment effect was obtained by adopting the technical route of processing. Other low grade noble metal materials and enrichment ratio of precious metals from the materials to acid products was high through acid leaching. This process has the advantages of simple process, environmental-friendly, strong adaptability of raw materials, high concentration ratio, which was regarded as a kind of the general efficient enrichment technology of low grade precious metal materials.
文摘A survey about OJSC "SIC Supermetal'" as a processor of secondary precious metal raw materials and a manufacturer of precious metal products for technical purposes,has been presented.Brief information has been given about the basic technologies and materials used in production,including dispersion strengthened materials on the basis of platinum alloys and laminar composites.
基金the Special Fund for the Development of Strategic and New Industry in Shenzhen,China(No.JCYJ20130329162012793)National Natural Science Foundation for Young Scholars,China(Nos.20907012,ZYC201105160189A)the Basic Research Plan in Shenzhen City,China(No.JC201105160593A)
文摘The activities of ZrO_2-supported precious metal catalysts for simultaneous removal of soot and NO_x in the presence of rich O_2and H_2O as well as SO_2 have been studied by keeping loose contact between catalyst and soot.The results show that only Ru,Ir and Rh have catalytic activity for simultaneous removal of soot and NO_x and the order of catalytic activity is Ru > Ir > Rh.Pt has the catalytic activity only for the removal of soot,and Ag,Pd,and Au have hardly any catalytic activities for the removal of soot and NO_x.The relationships between catalytic activity of precious metal catalysts and various reaction conditions were discussed.
基金financed by United Arab Emirates University(Grand Number 31B135-UPAR-3-2020)。
文摘This study examines the role of market sentiment in predicting the price bubbles of four strategic metal commodities(gold,silver,palladium,and platinum)from January 1985 to August 2020.It is the first to investigate this topic using sentiment indices,including news-based economic and consumer-based sentiments developed using different methods.We observed the role of sentiment as a reliable indicator of future bubbles for some metal commodities and found that bubbles were regularly concomi-tant with bearish sentiments for gold and platinum.Moreover,gold and palladium were the only commodities that experienced a bubble during the COVID-19 pandemic.Overall,our findings suggest inclusion of sentiment to the model that predicts the price bubbles of precious metals.
文摘The region of existence of phases in equilibrium with the solid solution based on palladium. Presented to analyze the current situation in the market of precious metals in Russia. Provides information about the production and processing of precious metals. Prospects for the most likely path of development of the Russian market of precious metals.
文摘In June 2012,the UN conference on sustainable development "Rio+20" summarized the work of the world community in this direction for last 20 years and outlined the tasks for the future.The UN website contains enough information to estimate the importance of global problems and "green economy," taking into account a very complicated state of the global and Russian markets which are balancing on the verge of crisis.Unfortunately,the website does not contain the materials of the 6th civilization forum "Long-Term Strategy for Sustainable Development on the Basis of Partnership of Civilizations:Concepts,Strategy,Programs and Projects" within the bounds of "Rio+20" which has considered the problems of a dialogue and partnership in conditions of extensive globalization.These problems are covered in the Partnership of Civilizations Journal which is issued in the Russian,English and Arabian languages,including its Internet version.The International Informatization Academy (it has the general consultative status at the Economic and Social Council of the UN) and its 20-year activity in the sphere of informatization of the world and Russia on the way to the partnership of civilizations,are presented there[1].
文摘Precious metals are highly demanded economic value metals that require to be recovered from industrial wastes and electronic used products (e-waste). They are such as gold (Au) as well as Platinum Group Metals (PGMs) for instance palladium (Pd) and platinum (Pt). The study was conducted to test the magnetic iron oxide nanoparticles modified with Moringa oleifera seed proteins as adsorbent for recovery of Au(III), Pd(II) and Pt(IV) from aqueous solutions. Different functional groups responsible for adsorption, morphology, thermal stability, and surface charges of the nanoparticles were characterized with FTIR, SEM, TGA and Zeta potential respectively. Batch adsorption method was used, and precious metal ions percentage recovery was measured using ICP-OES. The effects of pH, initial adsorbate concentration, adsorption agitation time and adsorbent dosage were studied at room temperature of 25°C. Au(III) yielded a maximal recovery of 99.8%, followed by Pt(IV) with 87.7%, then Pd(II) with 72.7% at a pH 2.5, 10 mg/L initial adsorbate concentration, 120 minutes agitation time and 0.065 g adsorbent dosage. These results suggested that modified iron oxide nanoparticles were effective in selective recovery of the precious metal ions.
