The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pres...The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M（metal）–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity（Vp） and shear wave velocity（Vs） of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.展开更多
Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparabl...Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparable to hydrothermally synthesized titanosilicalite (TS 1), much better than B ZSM 5 and Al ZSM 5. The effect of reaction conditions (solvent, feed space velocity, and water) on the catalytic performance of Ti ZSM 5 is studied. It is found that a quantitative relationship exists among the feed space velocity, the reaction time, and the CHO constant conversion. Ethanol or methanol as solvent shows higher activity, lactam selectivity, and stability than benzene and n hexanol. The addition of water to the rearrangement with a maximum amount of 1.0 mole per mole CHO results in the increase of CHO conversion while no meaningful changes in lactam selectivity and stability are observed.展开更多
This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine st...This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce_(2)Fe_(14)B,(Ce,Nd)_(2)Fe_(14)B and MM_(2)Fe_(14)B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting öEQ of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field Bhfincreases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the ^(57)Fe Mössbauer spectrometry due to its high sensitivity. On this basis,the content, magnetic behavior, and magnetization of the REFe_(2) phase, the amorphous grain boundary(GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.展开更多
Hepatitis B virus(HBV) infection is a global public health problem,with an estimated 350 million people worldwide chronically infected and approximately 500000 who die annually from HBV-related liver diseases.Manageme...Hepatitis B virus(HBV) infection is a global public health problem,with an estimated 350 million people worldwide chronically infected and approximately 500000 who die annually from HBV-related liver diseases.Management of chronic HBV is challenging and waves of guidelines emerge every year.One of the hottest topics and a matter of debate is the management of patients in their early immunotolerant phase of infection.With the lack of evidence,dealing with this particular subset of patients creates a great conflict with opposing views.In this review,the author highlights the pros and cons of these views and proposes a reasonable solution to resolve this dilemma.展开更多
Trace of B and Ga can substitute for Mo in Mn-Si-Cr dual phase steels.The technological process and CCT curves of steels treated with B and Ga are similar to those for Mn-Si-Cr-Mo steel.
A 1-b-methylcarbapenem analogue 6 was synthesized on polystyrene-diethylsilane resin (PS-DES) using 2-azetidinone bearing with 2-oxazolidone chiral auxiliary as starting material.
According to the experimental data of phase transition taken from DTA, metallography, SEM and microzone composition, two vertical sections of the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% andNd_2Fe_(14)BNd_...According to the experimental data of phase transition taken from DTA, metallography, SEM and microzone composition, two vertical sections of the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% andNd_2Fe_(14)BNd_(1.1)Fe_4B_4 , B≤44.56 at.-%) have been drawn in detail. It is verified that the crystallization of both Nd_2Fe_(14)B and Nd_(1.1)Fe_4B_4 phase, during cooling from melt, would take peritectic reaction instead of solid-liquid congruent precipita- tion.展开更多
ZTE Corporation announced on May 18, 2011 that it has won the world＇s first CDMA EV-DO Rev.B Phase 2 commercial contract from Indian telecom operator,Sistema Shyam TeleServices Ltd （SSTL）. SSTL operates its telecom...ZTE Corporation announced on May 18, 2011 that it has won the world＇s first CDMA EV-DO Rev.B Phase 2 commercial contract from Indian telecom operator,Sistema Shyam TeleServices Ltd （SSTL）. SSTL operates its telecom services ac＇ross India under the brand MrS and has over 11 million wireless customers. ZTE has also won the CDMA expansion contracts and EV-DO upgrade contracts for 10 circles of SSTL. The EV-DO Rev.B Phase 2 commercial launch will commence in Raiasthan.展开更多
基金Project supported by the Science Fund from the Key Laboratory of Earthquake Prediction,Institute of Earthquake Science,China Earthquake Administration(Grant No.2016IES010104)the National Natural Science Foundation of China(Grant Nos.41174071,41273073,41373060,and 41573121)
文摘The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M（metal）–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity（Vp） and shear wave velocity（Vs） of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.
基金the Foundations for Basic Research ofTsinghua U niversity and of China Petrochem icalCompany
文摘Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparable to hydrothermally synthesized titanosilicalite (TS 1), much better than B ZSM 5 and Al ZSM 5. The effect of reaction conditions (solvent, feed space velocity, and water) on the catalytic performance of Ti ZSM 5 is studied. It is found that a quantitative relationship exists among the feed space velocity, the reaction time, and the CHO constant conversion. Ethanol or methanol as solvent shows higher activity, lactam selectivity, and stability than benzene and n hexanol. The addition of water to the rearrangement with a maximum amount of 1.0 mole per mole CHO results in the increase of CHO conversion while no meaningful changes in lactam selectivity and stability are observed.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LY20E010002,LR18E010001,and LD19E010001)the National Natural Science Foundation of China(Grant Nos.U1704253 and 51801047)+2 种基金Liaoning Revitalization Talents Program(Grant No.XLYC1807177)the Key Research and Development plan of Zhejiang Province,China(Grant No.2020C05014)Ten Thousand Talents Plan of Zhejiang Province,China(Grant No.2018R52003)。
文摘This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce_(2)Fe_(14)B,(Ce,Nd)_(2)Fe_(14)B and MM_(2)Fe_(14)B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting öEQ of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field Bhfincreases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the ^(57)Fe Mössbauer spectrometry due to its high sensitivity. On this basis,the content, magnetic behavior, and magnetization of the REFe_(2) phase, the amorphous grain boundary(GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.
文摘Hepatitis B virus(HBV) infection is a global public health problem,with an estimated 350 million people worldwide chronically infected and approximately 500000 who die annually from HBV-related liver diseases.Management of chronic HBV is challenging and waves of guidelines emerge every year.One of the hottest topics and a matter of debate is the management of patients in their early immunotolerant phase of infection.With the lack of evidence,dealing with this particular subset of patients creates a great conflict with opposing views.In this review,the author highlights the pros and cons of these views and proposes a reasonable solution to resolve this dilemma.
文摘Trace of B and Ga can substitute for Mo in Mn-Si-Cr dual phase steels.The technological process and CCT curves of steels treated with B and Ga are similar to those for Mn-Si-Cr-Mo steel.
基金This work was financially supported by the National Natural Science Foundation of China (No. 29972037).
文摘A 1-b-methylcarbapenem analogue 6 was synthesized on polystyrene-diethylsilane resin (PS-DES) using 2-azetidinone bearing with 2-oxazolidone chiral auxiliary as starting material.
文摘According to the experimental data of phase transition taken from DTA, metallography, SEM and microzone composition, two vertical sections of the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% andNd_2Fe_(14)BNd_(1.1)Fe_4B_4 , B≤44.56 at.-%) have been drawn in detail. It is verified that the crystallization of both Nd_2Fe_(14)B and Nd_(1.1)Fe_4B_4 phase, during cooling from melt, would take peritectic reaction instead of solid-liquid congruent precipita- tion.
文摘ZTE Corporation announced on May 18, 2011 that it has won the world＇s first CDMA EV-DO Rev.B Phase 2 commercial contract from Indian telecom operator,Sistema Shyam TeleServices Ltd （SSTL）. SSTL operates its telecom services ac＇ross India under the brand MrS and has over 11 million wireless customers. ZTE has also won the CDMA expansion contracts and EV-DO upgrade contracts for 10 circles of SSTL. The EV-DO Rev.B Phase 2 commercial launch will commence in Raiasthan.
