A series of PtCuCeMgAl quintuple hydrotalcite-like compounds with different Ce contents were synthesized by one-pot method. After calcining and reduction, CeO_2-modified Mg(Al)O-supported Pt–Cu alloy catalysts were o...A series of PtCuCeMgAl quintuple hydrotalcite-like compounds with different Ce contents were synthesized by one-pot method. After calcining and reduction, CeO_2-modified Mg(Al)O-supported Pt–Cu alloy catalysts were obtained. To understand the effect of Cu and Ce, the structure and physico-chemistry properties of the catalysts were characterized and analyzed, and the catalytic behaviors were investigated in a direct dehydrogenation of propane to propene. The results show that the Pt^(4+), Cu^(2+), and Ce^(3+) ions can be incorporated into the brucite-like layers and the Ce content significantly affects the interaction strength between Pt and Cu and the dehydrogenation performance of propane. Under the reaction conditions, the highest propane conversion(45%) with 89% selectivity to propene and a 40% propene yield were achieved with a 0.3 wt% Ce-modified PtCu/Mg(Al)O catalyst. The improved catalytic performance is related to the easy formation of Pt–Cu alloy phase, excellent resistance to sintering, and coke deposits of active components modified by CeO_2.展开更多
Objective:The aim was to analyse the clinical features of leptomeningeal metastasis with banded high signal in the brainstem.Methods:In this paper,we report two cases of lung adenocarcinoma with soft meningeal metasta...Objective:The aim was to analyse the clinical features of leptomeningeal metastasis with banded high signal in the brainstem.Methods:In this paper,we report two cases of lung adenocarcinoma with soft meningeal metastasis,collected from the First Affiliated Hospital of Hainan Medical College,and searched the databases of CNKI,Wanfang,VIP,PubMed,Web of Science,and other databases which reported the MRI manifestation of"brainstem bandlike high signal",and collected the patients'past medical history,symptoms,signs,genetic findings,cerebrospinal fluid manifestation,treatment,and prognosis.Result:A total of 28 patients were included,of whom 26 had a history of lung adenocarcinoma and 2 were found to have occupational changes in the lungs.Magnetic resonance imaging(MRI)showed a band-like high signal in the ventral part of the brainstem on T2-FLAIR,symmetrical on both sides,which could extend to the cerebellar peduncles,with high signals on diffusion-weighted imaging(DWI),low signals on apparent diffusion coefficient(ADC),and long T1 signals on T1-weighted imaging,long T2 signals on T2 weighted imaging,and no long T2 signals on enhancement scan.T1-weighted imaging was a long T1 signal,T2-weighted imaging was a long T2 signal,and no enhancement was seen on enhanced scanning.Conclusion:It is important to recognize leptomeningeal metastasis of lung cancer,and the non-enhancing band of high signal in the brainstem on T2-FLAIR and DWI is likely to be the characteristic manifestation of leptomeningeal metastasis of non-small cell lung cancer.展开更多
Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the...Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.展开更多
In order to develop a novel electric light source, the doped high-silica glass was studied on the preparation and spectroscopic properties. ne porous glasses were made firstly and were then immersed in the solution co...In order to develop a novel electric light source, the doped high-silica glass was studied on the preparation and spectroscopic properties. ne porous glasses were made firstly and were then immersed in the solution containing Ce ion. Thereafter, the high-silica glasses containing Ce ion were prepared by sintering the porous preform. The spectroscopic properties were studied before and after heath treatment in H-2. The experimental results indicate that the suitable temperature schedules are the most important to prepare doped high-silica glass. The study of the spectra shows that Ce ion can be reduced to low valence state when it is heat-treated in H-2. It can be used to adjust the UV cut-off wavelength of high-silica glass by changing the valence state of Ce ion.展开更多
Chirality is one of the fundamental attributes of nature, which exists in different or even completely opposite metabolic,toxicological and pharmacological properties in organisms. Consequently, obtaining enantiomeric...Chirality is one of the fundamental attributes of nature, which exists in different or even completely opposite metabolic,toxicological and pharmacological properties in organisms. Consequently, obtaining enantiomerically pure drugs or optically active intermediates is highly desired in many fields like medicine, food and biochemistry. Thereby, it also promoted the development of various enantiomer selective separation techniques. Among the many chiral separation methods, chiral mobile phase additives(CMPAs) are widely used in various chromatographic techniques due to their simple operation,good versatility and low price. There have been a number of reviews on the research progress of CMPAs in last 2 decades,but they only reviewed the application of CMPAs in one specific chromatographic technique. Therefore, to provide a more comprehensive illustration of CMPAs in separation technology, their applications in high-performance liquid chromatography, capillary electrophoresis, countercurrent chromatography, nano-liquid chromatography were summarized and their advantages and disadvantages were briefly introduced in this critical review. The application of molecular simulation in the study of chiral separation mechanism was briefly summarized. We expect that it will provide researchers with the latest developments in this field and potential inspirations.展开更多
CuCeZrO_x and KCuCeZrO_x catalysts were synthesized and coated on the blank diesel particulate filter(DPF)substrate and a particulate matter(PM)loading apparatus was used for soot loading.The catalytic performances of...CuCeZrO_x and KCuCeZrO_x catalysts were synthesized and coated on the blank diesel particulate filter(DPF)substrate and a particulate matter(PM)loading apparatus was used for soot loading.The catalytic performances of soot oxidation were evaluated by temperature programmed combustion(TPC)test and characterization tests were conducted to investigate the physicochemical properties of the catalysts.The reaction mechanism in the oxidation process was analyzed with diffuse reflectance infrared Fourier transform spectroscopy.The results demonstrated that CuCeZrO_x catalyst exhibited high activities of soot oxidation at low temperature and the best results have been attained with Cu_(0.9)Ce_(0.05)Zr_(0.05)O_x over which the maximum soot oxidation rate decreased to 410~?C.Characterization tests have shown that catalysts containing 90%Cu have uniformly distributed grains and small particle sizes,which provide excellent oxidation activity by providing more active sites and forming a good bond between the catalyst and the soot.The low-temperature oxidation activity of soot could be further optimized due to the excellent elevated NO’s conversion rate by partially substituting Cu with K.The maximum particle oxidation rate can be easily realized at such a low temperature as 347~?C.展开更多
Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-e...Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.展开更多
Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. I...Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.展开更多
基金supported by the National Natural Science Foundation of China(No.21776214)the Natural Science Foundation of Jiangsu Province(No.BK20161166)the State Key Laboratory of Chemical Resource Engineering
文摘A series of PtCuCeMgAl quintuple hydrotalcite-like compounds with different Ce contents were synthesized by one-pot method. After calcining and reduction, CeO_2-modified Mg(Al)O-supported Pt–Cu alloy catalysts were obtained. To understand the effect of Cu and Ce, the structure and physico-chemistry properties of the catalysts were characterized and analyzed, and the catalytic behaviors were investigated in a direct dehydrogenation of propane to propene. The results show that the Pt^(4+), Cu^(2+), and Ce^(3+) ions can be incorporated into the brucite-like layers and the Ce content significantly affects the interaction strength between Pt and Cu and the dehydrogenation performance of propane. Under the reaction conditions, the highest propane conversion(45%) with 89% selectivity to propene and a 40% propene yield were achieved with a 0.3 wt% Ce-modified PtCu/Mg(Al)O catalyst. The improved catalytic performance is related to the easy formation of Pt–Cu alloy phase, excellent resistance to sintering, and coke deposits of active components modified by CeO_2.
基金Hainan Clinical Medical Center Construction Project(2021)Excellent Talent Team of Hainan Province(No.QRCBT202121)Key R&D Program of Hainan Province(No.ZDYF2022SHFZ109)。
文摘Objective:The aim was to analyse the clinical features of leptomeningeal metastasis with banded high signal in the brainstem.Methods:In this paper,we report two cases of lung adenocarcinoma with soft meningeal metastasis,collected from the First Affiliated Hospital of Hainan Medical College,and searched the databases of CNKI,Wanfang,VIP,PubMed,Web of Science,and other databases which reported the MRI manifestation of"brainstem bandlike high signal",and collected the patients'past medical history,symptoms,signs,genetic findings,cerebrospinal fluid manifestation,treatment,and prognosis.Result:A total of 28 patients were included,of whom 26 had a history of lung adenocarcinoma and 2 were found to have occupational changes in the lungs.Magnetic resonance imaging(MRI)showed a band-like high signal in the ventral part of the brainstem on T2-FLAIR,symmetrical on both sides,which could extend to the cerebellar peduncles,with high signals on diffusion-weighted imaging(DWI),low signals on apparent diffusion coefficient(ADC),and long T1 signals on T1-weighted imaging,long T2 signals on T2 weighted imaging,and no long T2 signals on enhancement scan.T1-weighted imaging was a long T1 signal,T2-weighted imaging was a long T2 signal,and no enhancement was seen on enhanced scanning.Conclusion:It is important to recognize leptomeningeal metastasis of lung cancer,and the non-enhancing band of high signal in the brainstem on T2-FLAIR and DWI is likely to be the characteristic manifestation of leptomeningeal metastasis of non-small cell lung cancer.
基金Project(GC13A113)supported by the Technology Research and Development Program of Heilongjiang Provincial Science and Technology DepartmentProject(12511469)supported by Heilongjiang Provincial Science and Technology Department
文摘Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.
文摘In order to develop a novel electric light source, the doped high-silica glass was studied on the preparation and spectroscopic properties. ne porous glasses were made firstly and were then immersed in the solution containing Ce ion. Thereafter, the high-silica glasses containing Ce ion were prepared by sintering the porous preform. The spectroscopic properties were studied before and after heath treatment in H-2. The experimental results indicate that the suitable temperature schedules are the most important to prepare doped high-silica glass. The study of the spectra shows that Ce ion can be reduced to low valence state when it is heat-treated in H-2. It can be used to adjust the UV cut-off wavelength of high-silica glass by changing the valence state of Ce ion.
基金financially funded by the National Key R&D Program of China(2019YFC1905500)the National Natural Science Foundation of China(21922409,21976131)Tianjin Research Program of Application Foundation and Advanced Technology(18JCZDJC37500)
文摘Chirality is one of the fundamental attributes of nature, which exists in different or even completely opposite metabolic,toxicological and pharmacological properties in organisms. Consequently, obtaining enantiomerically pure drugs or optically active intermediates is highly desired in many fields like medicine, food and biochemistry. Thereby, it also promoted the development of various enantiomer selective separation techniques. Among the many chiral separation methods, chiral mobile phase additives(CMPAs) are widely used in various chromatographic techniques due to their simple operation,good versatility and low price. There have been a number of reviews on the research progress of CMPAs in last 2 decades,but they only reviewed the application of CMPAs in one specific chromatographic technique. Therefore, to provide a more comprehensive illustration of CMPAs in separation technology, their applications in high-performance liquid chromatography, capillary electrophoresis, countercurrent chromatography, nano-liquid chromatography were summarized and their advantages and disadvantages were briefly introduced in this critical review. The application of molecular simulation in the study of chiral separation mechanism was briefly summarized. We expect that it will provide researchers with the latest developments in this field and potential inspirations.
基金the National Key R&D Program of China(Nos.2016YFC0205200 and 2016YFC0208000)the National Natural Science Foundation of China(No.51676127)
文摘CuCeZrO_x and KCuCeZrO_x catalysts were synthesized and coated on the blank diesel particulate filter(DPF)substrate and a particulate matter(PM)loading apparatus was used for soot loading.The catalytic performances of soot oxidation were evaluated by temperature programmed combustion(TPC)test and characterization tests were conducted to investigate the physicochemical properties of the catalysts.The reaction mechanism in the oxidation process was analyzed with diffuse reflectance infrared Fourier transform spectroscopy.The results demonstrated that CuCeZrO_x catalyst exhibited high activities of soot oxidation at low temperature and the best results have been attained with Cu_(0.9)Ce_(0.05)Zr_(0.05)O_x over which the maximum soot oxidation rate decreased to 410~?C.Characterization tests have shown that catalysts containing 90%Cu have uniformly distributed grains and small particle sizes,which provide excellent oxidation activity by providing more active sites and forming a good bond between the catalyst and the soot.The low-temperature oxidation activity of soot could be further optimized due to the excellent elevated NO’s conversion rate by partially substituting Cu with K.The maximum particle oxidation rate can be easily realized at such a low temperature as 347~?C.
基金financially supported by the National Natural Science Foundation of China (Nos.51672064 and U1435206)
文摘Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.
基金financially supported by the National Natural Science Foundation of China (Nos. 51672064 and U1435206)
文摘Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.
