The chemical and mineral compositions of bauxite recovered from the Severoonezhsk Bauxite Mine(Arkhangelsk region,Russia)were studied by XRD,ICP-OES,TG/DSC,SEM,TEM,and Mössbauer spectroscopy.The iron-containing m...The chemical and mineral compositions of bauxite recovered from the Severoonezhsk Bauxite Mine(Arkhangelsk region,Russia)were studied by XRD,ICP-OES,TG/DSC,SEM,TEM,and Mössbauer spectroscopy.The iron-containing minerals of the bauxites were found to comprise alumogoethite(α-Fe_(1−x)Al_(x)OOH),alumohematite(α-(Fe_(1−x)Al_(x))_(2)O_(3)),alumoakaganeite(β-Fe_(1−x)Al_(x)O(OH,Cl)),and chromite(FeCr_(2)O_(4)).The efficiency of Fe extraction from the bauxite by HCl leaching was 82.5%at 100℃,HCl concentration of 10%,solid/liquid ratio of 1:10,and the process duration of 60 min,with aluminum loss from the bauxites below 4.5%of the total Al contents in the bauxite.Analysis of the kinetics of the iron leaching process proved diffusion to be the limiting stage of the process at 90−100℃.Bauxite residue after leaching presented traces of α-Fe_(1−x)Al_(x)OOH and β-Fe_(1−x)Al_(x)O(OH,Cl),and most of the iron content was in the FeCr_(2)O_(4).In bauxite residue after HCl leaching,in addition to iron oxide,the contents of chromium and calcium oxides significantly decreased.The iron chloride liquor after leaching contained the rare earth elements(REE)of 6.8 mg/L Sc,4.1 mg/L Ce and 2.3 mg/L Ga.展开更多
Seeing is believing! Cryo-electron microscopy （cryo-EM） has greatly expanded the limit of human vision. The Nobel Prize in Chemistry 2017 was awarded to Jacques Dubochet, Joachim Frank and Richard Henderson for thei...Seeing is believing! Cryo-electron microscopy （cryo-EM） has greatly expanded the limit of human vision. The Nobel Prize in Chemistry 2017 was awarded to Jacques Dubochet, Joachim Frank and Richard Henderson for their development of cryo-EM. This method has revolutionized the structural study of biomolecules in the past few years. Now, scientists can routinely visualize many different kinds of biological ma- chineries with unprecedented details.展开更多
High-resolution scanning tunneling microscope images of iron phthalocyanine and zinc phthalocyanine molecules on Au（111） have been obtained using a functionalized tip of a scanning tunneling microscope （STM）, and ...High-resolution scanning tunneling microscope images of iron phthalocyanine and zinc phthalocyanine molecules on Au（111） have been obtained using a functionalized tip of a scanning tunneling microscope （STM）, and show rich intramolecular features that are not observed using clean tips. Ab initio density functional theory calculations and extended Huckel theory calculations revealed that the imaging of detailed electronic states is due specifically to the decoration of the STM tip with O2. The detailed structures are differentiated only when interacting with the highly directional orbitals of the oxygen molecules adsorbed on a truncated, [111]-oriented tungsten tip. Our results indicate a method for increasing the resolution in generic scans and thus, have potential applications in fundamental research based on high-resolution electronic states of molecules on metals, concerning, for example, chemical reactions, and catalysis mechanisms.展开更多
Ⅰ. INTRODUCTION The 1-vinylsilatrane is a compound with the presence of pentacoordinated silicon. Structural studies of this series of compounds have been reported. In the
In the structure study on the constituents of alcoholic extracts for the kernels of Schizandra Chinensis Baill, the crystal structure of Wuweizichun A P-bromobenzoyloxy ester has been previously determined. This work ...In the structure study on the constituents of alcoholic extracts for the kernels of Schizandra Chinensis Baill, the crystal structure of Wuweizichun A P-bromobenzoyloxy ester has been previously determined. This work aims at determining the crystal structure of 4-bromowuweizichun B, so as to understand further the characteristics of the structure of these compounds.展开更多
The Mo（Ⅲ） ion has a 4d3 electronic configuration, a nd the expected octahedral 6 coordination has been confirmed by some X-ray structural studies such as K3Mo （NCS）6. H2O·CH3COOH, MoCl3（py）3 and MoCl3（tu...The Mo（Ⅲ） ion has a 4d3 electronic configuration, a nd the expected octahedral 6 coordination has been confirmed by some X-ray structural studies such as K3Mo （NCS）6. H2O·CH3COOH, MoCl3（py）3 and MoCl3（tu）3, but results of structural research work are still not many. It seems to be worthy to take a further investigation of Mo （Ⅲ） complexes. et al. and Kumorita et al. had reported the preparation and some properties for MoCl3（urea）3. In order to obtain its further information about the struc-展开更多
基金Ministry of Science and Higher Education of the Russian Federation(scientific topic No.0137-2019-0023).
文摘The chemical and mineral compositions of bauxite recovered from the Severoonezhsk Bauxite Mine(Arkhangelsk region,Russia)were studied by XRD,ICP-OES,TG/DSC,SEM,TEM,and Mössbauer spectroscopy.The iron-containing minerals of the bauxites were found to comprise alumogoethite(α-Fe_(1−x)Al_(x)OOH),alumohematite(α-(Fe_(1−x)Al_(x))_(2)O_(3)),alumoakaganeite(β-Fe_(1−x)Al_(x)O(OH,Cl)),and chromite(FeCr_(2)O_(4)).The efficiency of Fe extraction from the bauxite by HCl leaching was 82.5%at 100℃,HCl concentration of 10%,solid/liquid ratio of 1:10,and the process duration of 60 min,with aluminum loss from the bauxites below 4.5%of the total Al contents in the bauxite.Analysis of the kinetics of the iron leaching process proved diffusion to be the limiting stage of the process at 90−100℃.Bauxite residue after leaching presented traces of α-Fe_(1−x)Al_(x)OOH and β-Fe_(1−x)Al_(x)O(OH,Cl),and most of the iron content was in the FeCr_(2)O_(4).In bauxite residue after HCl leaching,in addition to iron oxide,the contents of chromium and calcium oxides significantly decreased.The iron chloride liquor after leaching contained the rare earth elements(REE)of 6.8 mg/L Sc,4.1 mg/L Ce and 2.3 mg/L Ga.
文摘Seeing is believing! Cryo-electron microscopy （cryo-EM） has greatly expanded the limit of human vision. The Nobel Prize in Chemistry 2017 was awarded to Jacques Dubochet, Joachim Frank and Richard Henderson for their development of cryo-EM. This method has revolutionized the structural study of biomolecules in the past few years. Now, scientists can routinely visualize many different kinds of biological ma- chineries with unprecedented details.
基金This project is supported by the Natural Science Foundation of China （NSFC）, the Chinese National ＂973＂ project of the Ministry of Science and Technology （MOST）, the Chinese Academy of Sciences and the Shanghai Supercomputer Center, H. T. acknowledges the ＂Centre de Calcul en Midi-Pyrenees＂ （CALMIP） for computational resources. H. T. also thanks Sebastien Gauthier for useful discussions.
文摘High-resolution scanning tunneling microscope images of iron phthalocyanine and zinc phthalocyanine molecules on Au（111） have been obtained using a functionalized tip of a scanning tunneling microscope （STM）, and show rich intramolecular features that are not observed using clean tips. Ab initio density functional theory calculations and extended Huckel theory calculations revealed that the imaging of detailed electronic states is due specifically to the decoration of the STM tip with O2. The detailed structures are differentiated only when interacting with the highly directional orbitals of the oxygen molecules adsorbed on a truncated, [111]-oriented tungsten tip. Our results indicate a method for increasing the resolution in generic scans and thus, have potential applications in fundamental research based on high-resolution electronic states of molecules on metals, concerning, for example, chemical reactions, and catalysis mechanisms.
文摘Ⅰ. INTRODUCTION The 1-vinylsilatrane is a compound with the presence of pentacoordinated silicon. Structural studies of this series of compounds have been reported. In the
文摘In the structure study on the constituents of alcoholic extracts for the kernels of Schizandra Chinensis Baill, the crystal structure of Wuweizichun A P-bromobenzoyloxy ester has been previously determined. This work aims at determining the crystal structure of 4-bromowuweizichun B, so as to understand further the characteristics of the structure of these compounds.
文摘The Mo（Ⅲ） ion has a 4d3 electronic configuration, a nd the expected octahedral 6 coordination has been confirmed by some X-ray structural studies such as K3Mo （NCS）6. H2O·CH3COOH, MoCl3（py）3 and MoCl3（tu）3, but results of structural research work are still not many. It seems to be worthy to take a further investigation of Mo （Ⅲ） complexes. et al. and Kumorita et al. had reported the preparation and some properties for MoCl3（urea）3. In order to obtain its further information about the struc-
