The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents ...The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.展开更多
A quantitative analysis method of molybdenum in FeMo alloys by X-ray spectrometry using borate fusion technique was compared with that with pressed pellet. The complete pre-oxidation of FeMo alloys for the preparation...A quantitative analysis method of molybdenum in FeMo alloys by X-ray spectrometry using borate fusion technique was compared with that with pressed pellet. The complete pre-oxidation of FeMo alloys for the preparation of homogeneous fused discs was achieved by employing an automated fusion machine equipped with specially designed O2-blowing nozzles, which used lithium tetra-borate as flux with the addition of lithium nitrate (LiNO3) as oxidizer. The calibration curves of Mo and Fe were used in the quantitative analysis of standard materials and unknown plant samples with satisfactory accuracy and precision, utilizing the corrections of the matrix effects and line overlap. It was confirmed that the newly proposed method of preparing fused glass discs of FeMo alloys can replace the conventional wet chemical analyses requiring the labor intensive and time consuming procedure.展开更多
The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of ...The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of dimethyl ether(DME),which is derived from fossil resources,represents a promising approach to producing high-concentration formaldehyde with low energy consumption.However,there is still a lack of catalysts achieving satisfactory conversion of DME with high selectivity for formaldehyde under mild conditions.In this work,an efficient iron-molybdate(FeMo)catalyst was developed for the selective oxidation of DME to formaldehyde.The DME conversion of 84% was achieved with a superior formaldehyde selectivity(77%)at 300℃,a performance that is superior to all previously reported results.In an approximately 550 h continuous reaction,the catalyst maintained a conversion of 64% and a formaldehyde selectivity of 79%.Combined X-ray diffraction(XRD),Transmission electron microscope(TEM),Ultraviolet-visible spectroscopy(UV-Vis),Hydrogen temperature-programmed reduction(H_(2)-TPR),Fourier transform infrared(FT-IR)analyses,along with density functional theory(DFT)calculations,demonstrated that the excellent FeMo catalyst was composed of active Fe_(2)(MoO_(4))_(3)and MoO_(3)phases,and there was an interaction between them,which contributed to the efficient DME dissociation and smooth hydrogen spillover,leading to a superior DME conversion.With the support of DME/O_(2)pulse experiments,in-situ Raman,in-situ Dimethyl ether infrared spectroscopy(DME-IR)and DFT calculation results,a Mars-van Krevelen(MvK)reaction mechanism was proposed:DME was dissociated on the interface between Fe_(2)(MoO_(4))_(3)and MoO_(3)phases to form active methoxy species firstly,and it dehydrogenated to give hydrogen species;the generated hydrogen species smoothly spilled over from Fe_(2)(MoO_(4))_(3)to MoO_(3)enhanced by the interaction between Fe_(2)(MoO_(4))_(3)and MoO_(3);then the hydrogen species was consumed by MoO_(3),leading to a reduction of MoO_(3),and finally,the reduced MoO_(3)was re-oxidized by O_(2),returning to the initial state.These findings offer valuable insights not only for the development of efficient FeMo catalysts but also for elucidating the reaction mechanism involved in the oxidation of DME to formaldehyde,contributing to the optimized utilization of DME derived from fossil resources.展开更多
[目的]比较侧卧位和仰卧位行股骨近端防旋髓内钉(proximal femoral nail antirotation,PFNA)治疗老年股骨粗隆间骨折的临床疗效区别。[方法]回顾分析2008年5月～2010年2月本院收治的68例行股骨近端防旋髓内钉(PFNA)内固定治疗的老年股...[目的]比较侧卧位和仰卧位行股骨近端防旋髓内钉(proximal femoral nail antirotation,PFNA)治疗老年股骨粗隆间骨折的临床疗效区别。[方法]回顾分析2008年5月～2010年2月本院收治的68例行股骨近端防旋髓内钉(PFNA)内固定治疗的老年股骨粗隆间骨折患者,其中采用侧卧位徒手牵引36例和仰卧位牵引床牵引32例。对两组手术时间、术中出血量、手术切口长度、骨折愈合时间及术后1年Harris髋关节功能评分进行比较。[结果]侧卧位组在手术时间、术中出血量、手术切口长度方面比仰卧位组有优势(P<0.05),而在骨折愈合时间及术后1年髋关节功能评分方面两组比较无显著性差异(P>0.05)。[结论]侧卧位行PFNA治疗老年股骨粗隆间骨折具有手术时间短、创伤小、出血少、操作简单、术后恢复快等优点,值得推广。展开更多
[目的]比较PFNA(股骨近端防旋髓内钉proximal femoral nail anti-rotation)与DHS+TSP(动态髋螺钉及转子稳定钢板dynamic hip screw+trochanter stablizing plate)治疗股骨粗隆间不稳定型骨折的临床疗效。[方法]回顾分析2004年1月～2008...[目的]比较PFNA(股骨近端防旋髓内钉proximal femoral nail anti-rotation)与DHS+TSP(动态髋螺钉及转子稳定钢板dynamic hip screw+trochanter stablizing plate)治疗股骨粗隆间不稳定型骨折的临床疗效。[方法]回顾分析2004年1月～2008年8月本院收治的47例股骨粗隆间不稳定型骨折(AO分型A2型)病例,其中24例采用PFNA内固定,23例采用DHS+TSP内固定,对比两组患者的手术时间、术中失血量、术后卧床时间、术后关节功能,并用Harris评分系统进行评分,随访患者的骨折愈合情况,术后1周,3、6个月,1年复查。评价2种术式的疗效,分析手术相关并发症的原因。[结果]PFNA组平均手术时间(113±29)min,术中出血量(135±85)ml,术后Harris评分平均(89±3)分,患者中有1例头颈螺旋刀片切割股骨头的病例,无髋内翻病例,骨折均骨性愈合,平均愈合时间(5±1)个月。DHS+TSP组平均手术时间(156±35)min,术中出血量(429±266)ml,术后Harris评分平均(84±6)分,有1例患者术后因肺部感染死亡,2例出现头颈钉滑移,保守治疗后好转。PFNA较DHS+TSP治疗不稳定型股骨粗隆间骨折,手术时间短,P=0.002(P<0.05),卧床时间短,P=0.000(P<0.05),出血量少,P=0.001(P<0.05),髋关节Harris评分更高,P=0.006(P<0.05)。[结论]PFNA是治疗股骨粗隆间不稳定型骨折的良好固定材料,在治疗上较DHS+TSP具有操作简单、创伤小、骨折固定牢固、并发症少及术后患者可早期离床负重、髋关节功能恢复更好等优点,是一种治疗股骨粗隆间骨折的理想方法。展开更多
基金This work was financially supported by the Ministry of Commerce,Industry and Energy of Korea.
文摘The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.
文摘A quantitative analysis method of molybdenum in FeMo alloys by X-ray spectrometry using borate fusion technique was compared with that with pressed pellet. The complete pre-oxidation of FeMo alloys for the preparation of homogeneous fused discs was achieved by employing an automated fusion machine equipped with specially designed O2-blowing nozzles, which used lithium tetra-borate as flux with the addition of lithium nitrate (LiNO3) as oxidizer. The calibration curves of Mo and Fe were used in the quantitative analysis of standard materials and unknown plant samples with satisfactory accuracy and precision, utilizing the corrections of the matrix effects and line overlap. It was confirmed that the newly proposed method of preparing fused glass discs of FeMo alloys can replace the conventional wet chemical analyses requiring the labor intensive and time consuming procedure.
基金supported by the National Natural Science Foundation of China(U23A2088,22025206)the Dalian Innovation Support Plan for High Level Talents(2022RG13)+2 种基金DICP(Grant:DICP I202453,DICP I202234)the Fundamental Research Funds for the Central Universities(20720220008)support of the Liaoning Key Laboratory of Biomass Conversion for Energy and Material。
文摘The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of dimethyl ether(DME),which is derived from fossil resources,represents a promising approach to producing high-concentration formaldehyde with low energy consumption.However,there is still a lack of catalysts achieving satisfactory conversion of DME with high selectivity for formaldehyde under mild conditions.In this work,an efficient iron-molybdate(FeMo)catalyst was developed for the selective oxidation of DME to formaldehyde.The DME conversion of 84% was achieved with a superior formaldehyde selectivity(77%)at 300℃,a performance that is superior to all previously reported results.In an approximately 550 h continuous reaction,the catalyst maintained a conversion of 64% and a formaldehyde selectivity of 79%.Combined X-ray diffraction(XRD),Transmission electron microscope(TEM),Ultraviolet-visible spectroscopy(UV-Vis),Hydrogen temperature-programmed reduction(H_(2)-TPR),Fourier transform infrared(FT-IR)analyses,along with density functional theory(DFT)calculations,demonstrated that the excellent FeMo catalyst was composed of active Fe_(2)(MoO_(4))_(3)and MoO_(3)phases,and there was an interaction between them,which contributed to the efficient DME dissociation and smooth hydrogen spillover,leading to a superior DME conversion.With the support of DME/O_(2)pulse experiments,in-situ Raman,in-situ Dimethyl ether infrared spectroscopy(DME-IR)and DFT calculation results,a Mars-van Krevelen(MvK)reaction mechanism was proposed:DME was dissociated on the interface between Fe_(2)(MoO_(4))_(3)and MoO_(3)phases to form active methoxy species firstly,and it dehydrogenated to give hydrogen species;the generated hydrogen species smoothly spilled over from Fe_(2)(MoO_(4))_(3)to MoO_(3)enhanced by the interaction between Fe_(2)(MoO_(4))_(3)and MoO_(3);then the hydrogen species was consumed by MoO_(3),leading to a reduction of MoO_(3),and finally,the reduced MoO_(3)was re-oxidized by O_(2),returning to the initial state.These findings offer valuable insights not only for the development of efficient FeMo catalysts but also for elucidating the reaction mechanism involved in the oxidation of DME to formaldehyde,contributing to the optimized utilization of DME derived from fossil resources.
文摘[目的]比较侧卧位和仰卧位行股骨近端防旋髓内钉(proximal femoral nail antirotation,PFNA)治疗老年股骨粗隆间骨折的临床疗效区别。[方法]回顾分析2008年5月～2010年2月本院收治的68例行股骨近端防旋髓内钉(PFNA)内固定治疗的老年股骨粗隆间骨折患者,其中采用侧卧位徒手牵引36例和仰卧位牵引床牵引32例。对两组手术时间、术中出血量、手术切口长度、骨折愈合时间及术后1年Harris髋关节功能评分进行比较。[结果]侧卧位组在手术时间、术中出血量、手术切口长度方面比仰卧位组有优势(P<0.05),而在骨折愈合时间及术后1年髋关节功能评分方面两组比较无显著性差异(P>0.05)。[结论]侧卧位行PFNA治疗老年股骨粗隆间骨折具有手术时间短、创伤小、出血少、操作简单、术后恢复快等优点,值得推广。
文摘[目的]比较PFNA(股骨近端防旋髓内钉proximal femoral nail anti-rotation)与DHS+TSP(动态髋螺钉及转子稳定钢板dynamic hip screw+trochanter stablizing plate)治疗股骨粗隆间不稳定型骨折的临床疗效。[方法]回顾分析2004年1月～2008年8月本院收治的47例股骨粗隆间不稳定型骨折(AO分型A2型)病例,其中24例采用PFNA内固定,23例采用DHS+TSP内固定,对比两组患者的手术时间、术中失血量、术后卧床时间、术后关节功能,并用Harris评分系统进行评分,随访患者的骨折愈合情况,术后1周,3、6个月,1年复查。评价2种术式的疗效,分析手术相关并发症的原因。[结果]PFNA组平均手术时间(113±29)min,术中出血量(135±85)ml,术后Harris评分平均(89±3)分,患者中有1例头颈螺旋刀片切割股骨头的病例,无髋内翻病例,骨折均骨性愈合,平均愈合时间(5±1)个月。DHS+TSP组平均手术时间(156±35)min,术中出血量(429±266)ml,术后Harris评分平均(84±6)分,有1例患者术后因肺部感染死亡,2例出现头颈钉滑移,保守治疗后好转。PFNA较DHS+TSP治疗不稳定型股骨粗隆间骨折,手术时间短,P=0.002(P<0.05),卧床时间短,P=0.000(P<0.05),出血量少,P=0.001(P<0.05),髋关节Harris评分更高,P=0.006(P<0.05)。[结论]PFNA是治疗股骨粗隆间不稳定型骨折的良好固定材料,在治疗上较DHS+TSP具有操作简单、创伤小、骨折固定牢固、并发症少及术后患者可早期离床负重、髋关节功能恢复更好等优点,是一种治疗股骨粗隆间骨折的理想方法。
