A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the easter...A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that sili- con and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400℃. The favorable oxidation temperature of silicon was about 1 300-- 1 350℃. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.展开更多
In ramjet combustion chambers,carbon dioxide(CO_(2))produced by the combustion of carbonaceous fuel enters the chamber together with boron agglomerates.In order to investigate the effect of CO_(2)concentration present...In ramjet combustion chambers,carbon dioxide(CO_(2))produced by the combustion of carbonaceous fuel enters the chamber together with boron agglomerates.In order to investigate the effect of CO_(2)concentration present in an oxygen-containing atmosphere on the combustion characteristics and oxidation mechanisms of boron agglomerates,we used a laser ignition system,an X-ray diffractometer(XRD),and a thermogravimetric-differential scanning calorimetry(TG-DSC)combined thermal analysis system.Single-particle boron was tested in the laser-ignition experiments as the control group.The ignition experiment results showed that with a fixed O2 concentration of 20%,when the particle temperature reaches the melting point of boron,increasing CO_(2)content causes the combustion process of boron agglomerates to transition from single-particle molten droplet combustion to porous-particle combustion.Furthermore,XRD analysis results indicated that the condensed-phase combustion products(CCPs)of boron particles in a mixed atmosphere of O2 and CO_(2)contained B4C,which is responsible for the porous structure of the particles.At temperatures below 1200℃,the addition of CO_(2)has no obvious promotion effect on boron exothermic reaction.However,in the laser-ignition experiment,when the oxygen concentration was fixed at 20%while the CO_(2)concentration increased from 0%to 80%,the maximum temperature of boron agglomerates rose from 2434 to 2573 K,the self-sustaining combustion time of single-particle boron decreased from 396 to 169 ms,and the self-sustaining combustion time of boron agglomerates decreased from 198 to 40 ms.This study conclusively showed that adding CO_(2)to an oxygen-containing atmosphere facilitates boron reaction and consumption pathways,which is beneficial to promoting exothermic reaction of boron agglomerates at relatively high temperatures.展开更多
Organoboron reagents have garnered considerable attention due to their distinct properties. In recent years, boronic acids and boronate esters have been important intermediates for cross-coupling reactions and other f...Organoboron reagents have garnered considerable attention due to their distinct properties. In recent years, boronic acids and boronate esters have been important intermediates for cross-coupling reactions and other functional group construction and are often used to synthesize small organic molecules, drugs, and bioactive substances. In this feature article, we encapsulate the strategy of harnessing the unique properties of organoboron reagents to overcome challenges encountered in conventional polymer synthesis. We delve into the synthesis of boron-containing monomers and polymer materials, unraveling the unique attributes of these newfound polymers while offering innovative insights into their application within recyclable or reprocessable materials. We develop organoboron-based photocatalysts, employing their inner-sphere electron transfer(ISET) mechanisms to initiate controlled radical polymerization. We utilize alkylborane to initiate controlled radical polymerization and further designed B-alkylcatecholboranes to prepare ultra-high molecular weight polymers. Notably, we also propose a liquid-phase synthesis method based on organoboron tags and apply it to the precise synthesis of sequence-controlled conjugated polymers.These advancements open up new frontiers in the realm of polymer science, and the versatility and potential of organoboron reagents in polymer synthesis continue to inspire exciting research endeavors.展开更多
Organic diradicaloids with unique open-shell structures and properties have been widely used in organic electronics and spintronics.However,their advantageous optical properties have been explored less in the biomedic...Organic diradicaloids with unique open-shell structures and properties have been widely used in organic electronics and spintronics.However,their advantageous optical properties have been explored less in the biomedical field.In this work,the photothermal conversion behaviors of a boron-containing organic diradicaloid(BOD)are reported.BOD can assemble with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)to form rodlike nanoparticles(BOD NPs).These as-prepared BOD NPs exhibit high photothermal conversion capability and robust photothermal stability.Notably,they possess morphological superiority,which guarantees the effective photothermal therapy of tumors.This work thus demonstrates the promise of organic diradicaloids as efficient photothermal agents for biomedical applications.展开更多
A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw ...A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products （KMgPO4.6H2O） of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO （Chinese Pharmacopeia, 2O10 Edition） and for hydroxyapatite surgical implants （GB23101.1-2O08）. The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa＇6H2O, the main hydration product, determined the compressive strength.展开更多
The ubiquitousness of naturally occurring boron-containing compounds(BCCs) has led to their constant contact with humankind.Recently,many synthetic BCCs have been elaborated for a broad spectrum of purposes,especially...The ubiquitousness of naturally occurring boron-containing compounds(BCCs) has led to their constant contact with humankind.Recently,many synthetic BCCs have been elaborated for a broad spectrum of purposes,especially boric,boronic and borinic acids.Although BCCs were once employed primarily as antiseptics and later as antibiotics,they have become an increasingly relevant therapeutic tool.Nevertheless,this potential of BCCs has been drastically limited due to some unfortunate intra-hospital accidents in the 1940 s and 1950 s.The increasing use of BCCs as insecticides,antimicrobials,and other agents is providing new insights into their role in the physiology of several living species and in the pathophysiology of humans.It is becoming clear that BCCs act through a wide range of mechanisms,as do their corresponding boron-free counterparts.When comparing BCCs and similar boron-free compounds,in many cases the former show advantages in the medical field.The current minireview focuses on how BCCs have been developed by means of translational medicine,a process connecting biomedical research with clinical applications.This process of discovery is currently in an exponential stage.展开更多
In this study, the mass attenuation coefficient of boron-containing ores in the Liaoning province of China was calculated using Win XCOM software to investigate the shielding effectiveness of these ores against gamma ...In this study, the mass attenuation coefficient of boron-containing ores in the Liaoning province of China was calculated using Win XCOM software to investigate the shielding effectiveness of these ores against gamma rays. The mass attenuation coefficients were also calculated using MCNP-4 B code and compared with Win XCOM results; consequently, a good consistency between the results of Win XCOM and MCNP-4 B was observed. Furthermore, the G-P fitting method was used to evaluate the values of exposure buildup factor(EBF) in the energy range of 0.015–15 Me V up to 40 mean free paths. Among the selected ores, boron-bearing iron concentrate ore(M3)was determined to be the best gamma ray shielding ore owing to its higher values of mass attenuation coefficient and equivalent atomic number and lower value of EBF.Moreover, American Evaluated Nuclear Data File(ENDF/B-VII) was used to analyze the shielding effectivenessagainst thermal neutrons. It was determined that Szaibelyite(M2) is the best thermal neutron shielding material.This study would be useful for demonstrating the potential of boron-containing ores for applications in the field of nuclear engineering and technology.展开更多
Various boron-containing drugs have been approved for clinical use over the past two decades,and more are currently in clinical trials.The increasing interest in boron-containing compounds is due to their unique bindi...Various boron-containing drugs have been approved for clinical use over the past two decades,and more are currently in clinical trials.The increasing interest in boron-containing compounds is due to their unique binding properties to biological targets;for example,boron substitution can be used to modulate biological activity,pharmacokinetic properties,and drug resistance.In this perspective,we aim to comprehensively review the current status of boron compounds in drug discovery,focusing especially on progress from 2015 to December 2020.We classify these compounds into groups showing anticancer,antibacterial,antiviral,antiparasitic and other activities,and discuss the biological targets associated with each activity,as well as potential future developments.展开更多
The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according...The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shielding materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.展开更多
At Baoshan Iron ＆ Steel Co., Ltd., comer cracks of boron containing LCAK steel slabs had caused remarkable quality loss and mass flow disorder. With the help of fractography and thermodynamics analysis, the embrittle...At Baoshan Iron ＆ Steel Co., Ltd., comer cracks of boron containing LCAK steel slabs had caused remarkable quality loss and mass flow disorder. With the help of fractography and thermodynamics analysis, the embrittlement mechanism of this steel grade was studied and the results are as follows： 1 The transformation from 3＇ to a starts at the austenite grain boundaries and a layer of thin ferrite film gradually forms around the austenite grains. Strain concentration will preferentially start inside the ferrite phase when the stress accumulates to a certain level. 2 The coarse BN particles acceleratedly precipitated at the γ/α interfaces further deteriorate the ductility of the ferrite film, and brittleness results in strain concentration and microvoid coalescence inside the ferrite film. Therefore the austenite grain boundaries are prone to intergranular failure. 3 The stoichiometry among Al, N and B is a very important factor influencing the hot ductility of this steel grade. By controling the B-to-N atomic ratio to above 1, all N can be fixed by B instead of A1. Thus coarsegrained steel is available and fewer grain boundaries and higher ductility can reduce the risk of comer cracks. （4） By adjusting the B-to-N atomic ratio,Baoshan Iron ＆ Steel Co.,Ltd. successfully reduced the number of cracks to nearly one tenth of that in the past and the hot tensile tests confirmed remarkable improvement in the hot ductility of this steel.展开更多
Low carbon microalloyed steel containing 0.062 percent C, 2.34 percent Mn,0.044 percent Nb, 0.029 percent Ti, 0.032 percent V in mass fraction and small amount of B wasprepared in laboratory. Slabs of the steel were r...Low carbon microalloyed steel containing 0.062 percent C, 2.34 percent Mn,0.044 percent Nb, 0.029 percent Ti, 0.032 percent V in mass fraction and small amount of B wasprepared in laboratory. Slabs of the steel were rolled into plates of 6mm in thickness followed byaccelerated cooling. The plates possess very high yield strength and reasonable ductility, and theyield ratio is about 0.8. Ultra-fine ferrite structure with micrometer dimension was observed in thesurface layer of the plates. Moreover, the effect of the finishing rolling temperature on the finalmicrostructure and formation mechanism of ultra-fine ferrite as well as the gamma->alphatransformation behavior of the steel was discussed.展开更多
A novel boron-containing monomer,(4-(3,4-dicyanophenoxy)phenyl)boronic acid(BPhPN)was synthesized and used to promote the curing process of phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy)benzene(MPN).Differential s...A novel boron-containing monomer,(4-(3,4-dicyanophenoxy)phenyl)boronic acid(BPhPN)was synthesized and used to promote the curing process of phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy)benzene(MPN).Differential scanning calorimetry and rheological analysis were used to study the curing behaviors of BPhPN/MPN(namely B-MPN),and results suggested that B-MPN systems have better processibility.FTIR spectra and solid-state 13C-NMR exhibited triazine and isoindoline have been formed in the curing process.Boron-containing Lewis acid curing mechanism was preliminarily speculated and verified by two model compounds with different boron chemical environments.The thermogravimetric analysis and dynamic mechanical analysis demonstrated that the cured B-MPN polymers showed excellent thermal stability and heat resistance,which were comparable with conventional catalytic systems for phthalonitrile resins.This study not only presented a novel curing system for phthalonitrile resins,but also shed light on future design of high temperature thermosets.展开更多
Carbazole-based conjugated microporous polymers(CMPs)as a new type of advanced porous material have created tremendous research curiosities in the area of photocatalysis.Besides,introducing boron-containing dyes into ...Carbazole-based conjugated microporous polymers(CMPs)as a new type of advanced porous material have created tremendous research curiosities in the area of photocatalysis.Besides,introducing boron-containing dyes into the CMPs framework was rare but will be rather promising due to their unique properties,including strong electron-accepting capability,efficient catalytic behaviour,significant absorption coefficient and high quantum.Herein,we rationally designed and prepared two new CMPs,i.e.Cz-BF_(2)-CMP and Cz-BPh2-CMP with the combination of carbazole and boron-containing dye as electron donor and acceptor motifs,respectively.Due to the efficient D-A effect between carbazole and boron-dye which not only accelerated the interfacial charge transfer efficiency but also improved the separation capability of photogenerated electron-hole pairs,both CMPs exhibited excellent photocatalytic performances in organic transformations such as green synthesis of benzimidazole in aqueous solution and aerobic oxidation of thioether in EtOH.展开更多
基金Item Sponsored by National Natural Science Foundation of China and Shanghai Baosteel Group Corporation (50374024) Hi-Tech Research and Development Programof China (2006AA03Z529)
文摘A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that sili- con and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400℃. The favorable oxidation temperature of silicon was about 1 300-- 1 350℃. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.
基金the National Natural Science Foundation of China(No.52006240)the Hunan Provincial Natural Science Foundation of China(Nos.2020JJ4665 and 2021JJ30775).
文摘In ramjet combustion chambers,carbon dioxide(CO_(2))produced by the combustion of carbonaceous fuel enters the chamber together with boron agglomerates.In order to investigate the effect of CO_(2)concentration present in an oxygen-containing atmosphere on the combustion characteristics and oxidation mechanisms of boron agglomerates,we used a laser ignition system,an X-ray diffractometer(XRD),and a thermogravimetric-differential scanning calorimetry(TG-DSC)combined thermal analysis system.Single-particle boron was tested in the laser-ignition experiments as the control group.The ignition experiment results showed that with a fixed O2 concentration of 20%,when the particle temperature reaches the melting point of boron,increasing CO_(2)content causes the combustion process of boron agglomerates to transition from single-particle molten droplet combustion to porous-particle combustion.Furthermore,XRD analysis results indicated that the condensed-phase combustion products(CCPs)of boron particles in a mixed atmosphere of O2 and CO_(2)contained B4C,which is responsible for the porous structure of the particles.At temperatures below 1200℃,the addition of CO_(2)has no obvious promotion effect on boron exothermic reaction.However,in the laser-ignition experiment,when the oxygen concentration was fixed at 20%while the CO_(2)concentration increased from 0%to 80%,the maximum temperature of boron agglomerates rose from 2434 to 2573 K,the self-sustaining combustion time of single-particle boron decreased from 396 to 169 ms,and the self-sustaining combustion time of boron agglomerates decreased from 198 to 40 ms.This study conclusively showed that adding CO_(2)to an oxygen-containing atmosphere facilitates boron reaction and consumption pathways,which is beneficial to promoting exothermic reaction of boron agglomerates at relatively high temperatures.
基金supported by the National Natural Science Foundation of China (22271057, 22201045)the Natural Science Foundation of Shanghai (22ZR1406000)the State Key Laboratory of Molecular Engineering of Polymers,Department of Macromolecular Science, and Fudan University。
文摘Organoboron reagents have garnered considerable attention due to their distinct properties. In recent years, boronic acids and boronate esters have been important intermediates for cross-coupling reactions and other functional group construction and are often used to synthesize small organic molecules, drugs, and bioactive substances. In this feature article, we encapsulate the strategy of harnessing the unique properties of organoboron reagents to overcome challenges encountered in conventional polymer synthesis. We delve into the synthesis of boron-containing monomers and polymer materials, unraveling the unique attributes of these newfound polymers while offering innovative insights into their application within recyclable or reprocessable materials. We develop organoboron-based photocatalysts, employing their inner-sphere electron transfer(ISET) mechanisms to initiate controlled radical polymerization. We utilize alkylborane to initiate controlled radical polymerization and further designed B-alkylcatecholboranes to prepare ultra-high molecular weight polymers. Notably, we also propose a liquid-phase synthesis method based on organoboron tags and apply it to the precise synthesis of sequence-controlled conjugated polymers.These advancements open up new frontiers in the realm of polymer science, and the versatility and potential of organoboron reagents in polymer synthesis continue to inspire exciting research endeavors.
基金National Natural Science Foundation of China,Grant/Award Numbers:52003267,51973214,22175074Natural Science Foundation of Jilin Province,Grant/Award Numbers:YDZJ202101ZYTS027,20220101054JC。
文摘Organic diradicaloids with unique open-shell structures and properties have been widely used in organic electronics and spintronics.However,their advantageous optical properties have been explored less in the biomedical field.In this work,the photothermal conversion behaviors of a boron-containing organic diradicaloid(BOD)are reported.BOD can assemble with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)to form rodlike nanoparticles(BOD NPs).These as-prepared BOD NPs exhibit high photothermal conversion capability and robust photothermal stability.Notably,they possess morphological superiority,which guarantees the effective photothermal therapy of tumors.This work thus demonstrates the promise of organic diradicaloids as efficient photothermal agents for biomedical applications.
基金Funded by the National Natural Science Foundation of China(No.21276264)the Qinghai Province Science and TechnologyDepartment(No.2013-G-208)
文摘A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products （KMgPO4.6H2O） of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO （Chinese Pharmacopeia, 2O10 Edition） and for hydroxyapatite surgical implants （GB23101.1-2O08）. The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa＇6H2O, the main hydration product, determined the compressive strength.
基金Supported by Secretaria de Investigación y Posgrado del Instituto Politécnico Nacional,No.SIP-1754 20170411the National Council of Science and Technology,No.CONACYT,CB-235785
文摘The ubiquitousness of naturally occurring boron-containing compounds(BCCs) has led to their constant contact with humankind.Recently,many synthetic BCCs have been elaborated for a broad spectrum of purposes,especially boric,boronic and borinic acids.Although BCCs were once employed primarily as antiseptics and later as antibiotics,they have become an increasingly relevant therapeutic tool.Nevertheless,this potential of BCCs has been drastically limited due to some unfortunate intra-hospital accidents in the 1940 s and 1950 s.The increasing use of BCCs as insecticides,antimicrobials,and other agents is providing new insights into their role in the physiology of several living species and in the pathophysiology of humans.It is becoming clear that BCCs act through a wide range of mechanisms,as do their corresponding boron-free counterparts.When comparing BCCs and similar boron-free compounds,in many cases the former show advantages in the medical field.The current minireview focuses on how BCCs have been developed by means of translational medicine,a process connecting biomedical research with clinical applications.This process of discovery is currently in an exponential stage.
基金supported by the National Natural Science Foundation of China(Nos.51472048,50774022)the Key Laboratory Project of Liaoning Province Education Office(No.LZ 2014-022)
文摘In this study, the mass attenuation coefficient of boron-containing ores in the Liaoning province of China was calculated using Win XCOM software to investigate the shielding effectiveness of these ores against gamma rays. The mass attenuation coefficients were also calculated using MCNP-4 B code and compared with Win XCOM results; consequently, a good consistency between the results of Win XCOM and MCNP-4 B was observed. Furthermore, the G-P fitting method was used to evaluate the values of exposure buildup factor(EBF) in the energy range of 0.015–15 Me V up to 40 mean free paths. Among the selected ores, boron-bearing iron concentrate ore(M3)was determined to be the best gamma ray shielding ore owing to its higher values of mass attenuation coefficient and equivalent atomic number and lower value of EBF.Moreover, American Evaluated Nuclear Data File(ENDF/B-VII) was used to analyze the shielding effectivenessagainst thermal neutrons. It was determined that Szaibelyite(M2) is the best thermal neutron shielding material.This study would be useful for demonstrating the potential of boron-containing ores for applications in the field of nuclear engineering and technology.
基金Financial support from the National Natural Science Foundation of China(No.81973181,to Xinyong Liu,China)Shandong Provincial Key Research and Development Project(No.2019JZZY021011,to Peng Zhan,China)+5 种基金National Science and Technology Major Projects for“Major New Drugs Innovation and Development”(2019ZX09301126,to Xinyong Liu,China)Outstanding Youth Fund of Shandong Province(ZR2020JQ31,to Peng Zhan,China)Foreign Cultural and Educational Experts Project(GXL20200015001,to Xinyong Liu,China)the Program for Outstanding Ph.D.Candidate of Shandong University(to Lin Sun,China)Qilu Young Scholars Program of Shandong University(to Peng Zhan,China)the Taishan Scholar Program at Shandong Province(to Xinyong Liu,China)。
文摘Various boron-containing drugs have been approved for clinical use over the past two decades,and more are currently in clinical trials.The increasing interest in boron-containing compounds is due to their unique binding properties to biological targets;for example,boron substitution can be used to modulate biological activity,pharmacokinetic properties,and drug resistance.In this perspective,we aim to comprehensively review the current status of boron compounds in drug discovery,focusing especially on progress from 2015 to December 2020.We classify these compounds into groups showing anticancer,antibacterial,antiviral,antiparasitic and other activities,and discuss the biological targets associated with each activity,as well as potential future developments.
文摘The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shielding materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.
文摘At Baoshan Iron ＆ Steel Co., Ltd., comer cracks of boron containing LCAK steel slabs had caused remarkable quality loss and mass flow disorder. With the help of fractography and thermodynamics analysis, the embrittlement mechanism of this steel grade was studied and the results are as follows： 1 The transformation from 3＇ to a starts at the austenite grain boundaries and a layer of thin ferrite film gradually forms around the austenite grains. Strain concentration will preferentially start inside the ferrite phase when the stress accumulates to a certain level. 2 The coarse BN particles acceleratedly precipitated at the γ/α interfaces further deteriorate the ductility of the ferrite film, and brittleness results in strain concentration and microvoid coalescence inside the ferrite film. Therefore the austenite grain boundaries are prone to intergranular failure. 3 The stoichiometry among Al, N and B is a very important factor influencing the hot ductility of this steel grade. By controling the B-to-N atomic ratio to above 1, all N can be fixed by B instead of A1. Thus coarsegrained steel is available and fewer grain boundaries and higher ductility can reduce the risk of comer cracks. （4） By adjusting the B-to-N atomic ratio,Baoshan Iron ＆ Steel Co.,Ltd. successfully reduced the number of cracks to nearly one tenth of that in the past and the hot tensile tests confirmed remarkable improvement in the hot ductility of this steel.
基金This work was financially supported by the State Foundation of China for Fundamental Research(No.G1998061500).
文摘Low carbon microalloyed steel containing 0.062 percent C, 2.34 percent Mn,0.044 percent Nb, 0.029 percent Ti, 0.032 percent V in mass fraction and small amount of B wasprepared in laboratory. Slabs of the steel were rolled into plates of 6mm in thickness followed byaccelerated cooling. The plates possess very high yield strength and reasonable ductility, and theyield ratio is about 0.8. Ultra-fine ferrite structure with micrometer dimension was observed in thesurface layer of the plates. Moreover, the effect of the finishing rolling temperature on the finalmicrostructure and formation mechanism of ultra-fine ferrite as well as the gamma->alphatransformation behavior of the steel was discussed.
基金financially supported by the National Natural Science Foundation of China(Nos.51803059,51873215 and 52003272)Beijing Natural Science Foundation of China(No.2204101)the Youth Innovation Promotion Association of CAS(No.2017047)。
文摘A novel boron-containing monomer,(4-(3,4-dicyanophenoxy)phenyl)boronic acid(BPhPN)was synthesized and used to promote the curing process of phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy)benzene(MPN).Differential scanning calorimetry and rheological analysis were used to study the curing behaviors of BPhPN/MPN(namely B-MPN),and results suggested that B-MPN systems have better processibility.FTIR spectra and solid-state 13C-NMR exhibited triazine and isoindoline have been formed in the curing process.Boron-containing Lewis acid curing mechanism was preliminarily speculated and verified by two model compounds with different boron chemical environments.The thermogravimetric analysis and dynamic mechanical analysis demonstrated that the cured B-MPN polymers showed excellent thermal stability and heat resistance,which were comparable with conventional catalytic systems for phthalonitrile resins.This study not only presented a novel curing system for phthalonitrile resins,but also shed light on future design of high temperature thermosets.
基金We are grateful for financial support from the National Natural Science Foundation of China(No.U1808210)the Natural Science Foundation of Liaoning Province(No.2019-MS-046)the Open Sharing Fund for the Large-scale Instruments and Equipment of Dalian University of Technology(Nos.DUTKFJJ2021086 and DUTKFJJ2021122).
文摘Carbazole-based conjugated microporous polymers(CMPs)as a new type of advanced porous material have created tremendous research curiosities in the area of photocatalysis.Besides,introducing boron-containing dyes into the CMPs framework was rare but will be rather promising due to their unique properties,including strong electron-accepting capability,efficient catalytic behaviour,significant absorption coefficient and high quantum.Herein,we rationally designed and prepared two new CMPs,i.e.Cz-BF_(2)-CMP and Cz-BPh2-CMP with the combination of carbazole and boron-containing dye as electron donor and acceptor motifs,respectively.Due to the efficient D-A effect between carbazole and boron-dye which not only accelerated the interfacial charge transfer efficiency but also improved the separation capability of photogenerated electron-hole pairs,both CMPs exhibited excellent photocatalytic performances in organic transformations such as green synthesis of benzimidazole in aqueous solution and aerobic oxidation of thioether in EtOH.
