Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spec...Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.展开更多
Background and Objectives: The species to the Lannea genus are trees, shrubs with compound leaves. Thus, individuals called atypical Lannea with single leaves and of socio-economic interests have been identified in th...Background and Objectives: The species to the Lannea genus are trees, shrubs with compound leaves. Thus, individuals called atypical Lannea with single leaves and of socio-economic interests have been identified in the central plateau region (Burkina Faso). This study aimed to contribute to the identification of atypical species. Material and Methods: The Polymerase Chain Reaction (PCR) method using specific primers was performed and consisted of extracting DNA from young leaves of Lannea individuals, amplifying and then sequencing portions of discriminating DNA (matK, rbcL and rps16). Results: It was shown that individuals belong to the Lannea genus, but are subdivided into three subgroups: a first subgroup containing Lannea microcarpa and two subgroups with no previously identified Lannea species. Conclusion: These atypical individuals are ecotypes or mutants of Lannea microcarpa.展开更多
The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to charact...The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to characterize the electrode materials to study their structures,redox mechanisms and electrochemical performances.In this review,the common characterization methods that have been adopted so far are summarized from two aspects:experimental characterization and theoretical calculation.The experimental characterization is introduced in detail from structural characterization,electrochemical characterization and electrode reaction chara cterization.The experimental purposes and working principles of various experimental characterization methods are briefly illustrated.As the auxilia ry means,theoretical calculation provides the theoretical basis for characterizing the electrochemical reaction mechanism of organic electrode materials.Through these characterizations,we will have a deep understanding about the material structures,electrochemical redox mechanisms,electrochemical properties and the relationships of structure-property.It is hoped that this review would help researchers to select the suitable characterization methods to analyze the structures and performances of organic electrode materials quickly and effectively.展开更多
A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ a...A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.展开更多
Offwhite pure Fe2P207 was synthesized through solid phase reaction using Fe203 and NH4H2PO4 in argon atmosphere. The reaction products of Fe203 and NHaH2PO4 at a series of temperatures from 400 to 900 ℃ were characte...Offwhite pure Fe2P207 was synthesized through solid phase reaction using Fe203 and NH4H2PO4 in argon atmosphere. The reaction products of Fe203 and NHaH2PO4 at a series of temperatures from 400 to 900 ℃ were characterized by XRD. Comparison and analysis of XRD patterns of resultant products indicated well-crystallized Fe2P207 could be obtained over 630 ℃ and Fe2P207 prepared at 700 ℃ was triclinic in cell type. Comparison of the cell parameters proved that the as-prepared Fe2P207 belonged to β- Fe2P207 in crystal phase and SEM showed its size distribution was 0.5-2 μm.展开更多
Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuously followed by filtration as raw materials with a molar ratio of 1∶1 of MgCl2 to NH4Cl, ammonium carnallite was synth...Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuously followed by filtration as raw materials with a molar ratio of 1∶1 of MgCl2 to NH4Cl, ammonium carnallite was synthesized. And then the ammonium carnallite was dehydrated to some extent at 160℃ for 4 h. Ammonium carnallite reacted with ammonia at 240℃ for 150 min and the ammonation ammonium carnallite was produced. Finally, the ammonation ammonium carnallite was calcined at 750℃ into anhydrous magnesium chloride containing only 0.1%（mass fraction） of MgO. On the other hand, dehydrated ammonium carnallite was mixed with the solid ammonium chloride at mass ratio 1∶4 at high temperature and with the differential pressure of NH3 above 30.5kPa. The dehydrated ammonium carnallite of mixture was dehydrated at 410℃, and then calcined at 700℃ into anhydrous magnesium chloride with only 0.087%（mass fraction） of MgO. X-ray diffraction and electron microscopy analysis results prove that anhydrous magnesium chloride obtained by both methods hasn’t mixed phases, the particle is large and even has good dispersion, which is suitable for preparation of metal magnesium in the electrolysis.展开更多
Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) ...Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar. A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to μGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit.展开更多
Meat constitutes the main source of protein and occupies an important place in our diet. Indeed, the production of poultry and beef has increased. However, the hygienic quality of meat is not always guaranteed. Microo...Meat constitutes the main source of protein and occupies an important place in our diet. Indeed, the production of poultry and beef has increased. However, the hygienic quality of meat is not always guaranteed. Microorganisms such as Escherichia coli can be found in meat and can cause various infections including diarrhea, dysentery, food poisoning, gastroenteritis or typhoid fever. Thus, the present study was designed to characterize Escherichia coli (E. coli) from beef and chicken consumed in restaurants in Yaoundé Cameroon. A total of 105 meat samples (60 beef and 45 chickens) were subjected to microbial culture for E. coli isolation and further confirmed by Polymerase Chain Reaction (PCR) using primers EC-F and EC-R that are specific to E. coli 16S rRNA gene. The supplier source, storage, and transport conditions were taken into consideration during sample analysis and data processing. This study revealed that 77/105 samples (73.33%) were positive for E. coli following microbial culture and 35 (33.33%) were positive for E. coli following molecular examination. A statistically significant difference was observed when PCR and microbial culture were used to assess for E. coli in beef and a non-statistically significant difference was observed in the case of chicken meat. Also, a statistically significant difference was noticed with the different transport conditions, but this wasn’t the case with the supplier source as well as the storage conditions where a non-statistically significant difference was seen. This study revealed that PCR-based methods are fast and reliable in the identification and characterization of Escherichia coli in meats (beef and chicken) as well as in assessing the prevalence of pathogenic E. coli, in Cameroon.展开更多
基金This work was financially supported by the Teaching Reform Study Program of Ludong University (No.Y0715).
文摘Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.
文摘Background and Objectives: The species to the Lannea genus are trees, shrubs with compound leaves. Thus, individuals called atypical Lannea with single leaves and of socio-economic interests have been identified in the central plateau region (Burkina Faso). This study aimed to contribute to the identification of atypical species. Material and Methods: The Polymerase Chain Reaction (PCR) method using specific primers was performed and consisted of extracting DNA from young leaves of Lannea individuals, amplifying and then sequencing portions of discriminating DNA (matK, rbcL and rps16). Results: It was shown that individuals belong to the Lannea genus, but are subdivided into three subgroups: a first subgroup containing Lannea microcarpa and two subgroups with no previously identified Lannea species. Conclusion: These atypical individuals are ecotypes or mutants of Lannea microcarpa.
基金the financial support of the National Natural Science Foundation of China(Nos.21875206,21403187)the Natural Science Foundation of Hebei Province(No.B2019203487)the open project in Key Lab Adv.Energy Mat.Chem.(Nankai University)。
文摘The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to characterize the electrode materials to study their structures,redox mechanisms and electrochemical performances.In this review,the common characterization methods that have been adopted so far are summarized from two aspects:experimental characterization and theoretical calculation.The experimental characterization is introduced in detail from structural characterization,electrochemical characterization and electrode reaction chara cterization.The experimental purposes and working principles of various experimental characterization methods are briefly illustrated.As the auxilia ry means,theoretical calculation provides the theoretical basis for characterizing the electrochemical reaction mechanism of organic electrode materials.Through these characterizations,we will have a deep understanding about the material structures,electrochemical redox mechanisms,electrochemical properties and the relationships of structure-property.It is hoped that this review would help researchers to select the suitable characterization methods to analyze the structures and performances of organic electrode materials quickly and effectively.
文摘A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.
文摘Offwhite pure Fe2P207 was synthesized through solid phase reaction using Fe203 and NH4H2PO4 in argon atmosphere. The reaction products of Fe203 and NHaH2PO4 at a series of temperatures from 400 to 900 ℃ were characterized by XRD. Comparison and analysis of XRD patterns of resultant products indicated well-crystallized Fe2P207 could be obtained over 630 ℃ and Fe2P207 prepared at 700 ℃ was triclinic in cell type. Comparison of the cell parameters proved that the as-prepared Fe2P207 belonged to β- Fe2P207 in crystal phase and SEM showed its size distribution was 0.5-2 μm.
基金Project(2000 G 101) supported by the Key Science and Technology Research Project of Qinghai Province
文摘Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuously followed by filtration as raw materials with a molar ratio of 1∶1 of MgCl2 to NH4Cl, ammonium carnallite was synthesized. And then the ammonium carnallite was dehydrated to some extent at 160℃ for 4 h. Ammonium carnallite reacted with ammonia at 240℃ for 150 min and the ammonation ammonium carnallite was produced. Finally, the ammonation ammonium carnallite was calcined at 750℃ into anhydrous magnesium chloride containing only 0.1%（mass fraction） of MgO. On the other hand, dehydrated ammonium carnallite was mixed with the solid ammonium chloride at mass ratio 1∶4 at high temperature and with the differential pressure of NH3 above 30.5kPa. The dehydrated ammonium carnallite of mixture was dehydrated at 410℃, and then calcined at 700℃ into anhydrous magnesium chloride with only 0.087%（mass fraction） of MgO. X-ray diffraction and electron microscopy analysis results prove that anhydrous magnesium chloride obtained by both methods hasn’t mixed phases, the particle is large and even has good dispersion, which is suitable for preparation of metal magnesium in the electrolysis.
文摘Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar. A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to μGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit.
文摘Meat constitutes the main source of protein and occupies an important place in our diet. Indeed, the production of poultry and beef has increased. However, the hygienic quality of meat is not always guaranteed. Microorganisms such as Escherichia coli can be found in meat and can cause various infections including diarrhea, dysentery, food poisoning, gastroenteritis or typhoid fever. Thus, the present study was designed to characterize Escherichia coli (E. coli) from beef and chicken consumed in restaurants in Yaoundé Cameroon. A total of 105 meat samples (60 beef and 45 chickens) were subjected to microbial culture for E. coli isolation and further confirmed by Polymerase Chain Reaction (PCR) using primers EC-F and EC-R that are specific to E. coli 16S rRNA gene. The supplier source, storage, and transport conditions were taken into consideration during sample analysis and data processing. This study revealed that 77/105 samples (73.33%) were positive for E. coli following microbial culture and 35 (33.33%) were positive for E. coli following molecular examination. A statistically significant difference was observed when PCR and microbial culture were used to assess for E. coli in beef and a non-statistically significant difference was observed in the case of chicken meat. Also, a statistically significant difference was noticed with the different transport conditions, but this wasn’t the case with the supplier source as well as the storage conditions where a non-statistically significant difference was seen. This study revealed that PCR-based methods are fast and reliable in the identification and characterization of Escherichia coli in meats (beef and chicken) as well as in assessing the prevalence of pathogenic E. coli, in Cameroon.
