The recently introduced even-odd rule has been shown to successfully represent chemical structures of ions and molecules. While comparing available drawings in the scientific literature with the list of compounds pred...The recently introduced even-odd rule has been shown to successfully represent chemical structures of ions and molecules. While comparing available drawings in the scientific literature with the list of compounds predicted by the even-odd rule, it became however obvious that existing compounds are fewer than expected. Several predicted compounds involving many covalent bonds have apparently never been experimentally observed. Neutral oxygen for instance is expected to have 6 valence electrons, whereas oxygen can only build a maximum of two bonds, as in water. This specificity is observed for elements in the top-right corner of the periodic table. For compounds to contain only single covalent bonds, and thus follow the even-odd rule, further explanations are necessary. The present paper proposes that those specific elements experience a transfer of electrons from the valence shell into the inner shell, making them unavailable for further bonding. These elements will be described as organic, hereby providing a clear and hopefully unifying definition of the term. In opposition, inorganic elements have a constant inner shell no matter their electrical state or the number of bonds they maintain. More than 70 compounds involving 11 elements of the main group are studied, revealing a progression from fully inorganic elements at the left of the periodic table to fully organic elements. The transition between inorganic or organic elements is made of few elements that take an organic form when negatively charged;they are labelled semi-organic. The article concludes that the fully organic elements of the main group are Oxygen and Fluorine, whereas semi-organic elements are more numerous: C, N, S, Cl, Se, Br and I. Thus, the even-odd rule becomes fully compatible with scientific knowledge of compounds in liquid or gaseous phase.展开更多
The inner shell surface is the biomineralization site in shell formation and an inner-shell film covers it. This surface is composed of two regions： an outer calcitic region and an inner aragonitic region. In this st...The inner shell surface is the biomineralization site in shell formation and an inner-shell film covers it. This surface is composed of two regions： an outer calcitic region and an inner aragonitic region. In this study, some amalgamated calcite crystals were found in the calcitic region and some aragonitic ＂imprints＂ were found in the central part of the aragonitic region. The ＂imprints＂ are probably the trace of mantle cells that adhered to the inner shell surface when the shell was produced. Furthermore, to build a novel in vitro biomineralization system, the inner-shell film was detached from the shell and introduced to the calcitic crystallization solution. Crystallization experiments showed that nacre proteins could induce aragonite crystals in the novel system but inhibited calcite growth in the absence of the inner-shell film. These data suggested that the inner-shell film may induce aragonite growth in vivo by combining nacre proteins.展开更多
A 3D elasto-plastic finite element(FE)model of power spinning of thin-walled aluminum alloy shell with hoop inner rib was established under software ABAQUS.Key technologies were dealt with reasonably.The reliability o...A 3D elasto-plastic finite element(FE)model of power spinning of thin-walled aluminum alloy shell with hoop inner rib was established under software ABAQUS.Key technologies were dealt with reasonably.The reliability of the FE model was verified theoretically and experimentally.The forming process was simulated and studied.The distribution of the thickness and stress,and the variations of spinning force were obtained.The workpiece springback was analyzed with ABAQUS/Standard.The results show that the FE model considering elastic deformation can not only be used to analyze the workpiece springback in the complex spinning process,but also serve as a significant guide to study the local deformation mechanism and choose the reasonable parameters.展开更多
Discusses the elastic deformation of ellipsoidal shell of different axis ratio under inner pressure during hydraulic bulging forming with theoretical results in good agreement with actual result, thereby providing the...Discusses the elastic deformation of ellipsoidal shell of different axis ratio under inner pressure during hydraulic bulging forming with theoretical results in good agreement with actual result, thereby providing theoretical basis for hydraulic bulging forming of ellipsoidal shell.展开更多
Fe K-shell ionization cross sections induced by 2.4-6.0 MeV Xe^20＋ are measured and compared with different binary- encounter-approximation （BEA） models. The results indicate that the BEA model corrected both by th...Fe K-shell ionization cross sections induced by 2.4-6.0 MeV Xe^20＋ are measured and compared with different binary- encounter-approximation （BEA） models. The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge （Zeff） agrees well with the experimental data. Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states （20＋, 22＋, 26＋, 30＋） verifies the applicability of the effective nuclear charge （Zeff） correction for the BEA model. It is found that Zeff correction is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies. However, when the M shell is opened, the Zeff corrected BEA model is unable to explain the inner-shell ionization, and the electron transfer by molecular-orbital promotion should be considered.展开更多
文摘The recently introduced even-odd rule has been shown to successfully represent chemical structures of ions and molecules. While comparing available drawings in the scientific literature with the list of compounds predicted by the even-odd rule, it became however obvious that existing compounds are fewer than expected. Several predicted compounds involving many covalent bonds have apparently never been experimentally observed. Neutral oxygen for instance is expected to have 6 valence electrons, whereas oxygen can only build a maximum of two bonds, as in water. This specificity is observed for elements in the top-right corner of the periodic table. For compounds to contain only single covalent bonds, and thus follow the even-odd rule, further explanations are necessary. The present paper proposes that those specific elements experience a transfer of electrons from the valence shell into the inner shell, making them unavailable for further bonding. These elements will be described as organic, hereby providing a clear and hopefully unifying definition of the term. In opposition, inorganic elements have a constant inner shell no matter their electrical state or the number of bonds they maintain. More than 70 compounds involving 11 elements of the main group are studied, revealing a progression from fully inorganic elements at the left of the periodic table to fully organic elements. The transition between inorganic or organic elements is made of few elements that take an organic form when negatively charged;they are labelled semi-organic. The article concludes that the fully organic elements of the main group are Oxygen and Fluorine, whereas semi-organic elements are more numerous: C, N, S, Cl, Se, Br and I. Thus, the even-odd rule becomes fully compatible with scientific knowledge of compounds in liquid or gaseous phase.
基金The National Natural Science Foundation of China under grant Nos 30871911 and 40876068the National High Technology Research and Development Program of China under contract No.2010AA09Z405the Program of Environmental Protection Commonweal Research under contract No. 2007HBGY26
文摘The inner shell surface is the biomineralization site in shell formation and an inner-shell film covers it. This surface is composed of two regions： an outer calcitic region and an inner aragonitic region. In this study, some amalgamated calcite crystals were found in the calcitic region and some aragonitic ＂imprints＂ were found in the central part of the aragonitic region. The ＂imprints＂ are probably the trace of mantle cells that adhered to the inner shell surface when the shell was produced. Furthermore, to build a novel in vitro biomineralization system, the inner-shell film was detached from the shell and introduced to the calcitic crystallization solution. Crystallization experiments showed that nacre proteins could induce aragonite crystals in the novel system but inhibited calcite growth in the absence of the inner-shell film. These data suggested that the inner-shell film may induce aragonite growth in vivo by combining nacre proteins.
基金Projects(5040503950575186)supported by the National Natural Science Foundation of ChinaProject(50225518)supported by the National Science Foundation of China for Distinguished Young Scholars
文摘A 3D elasto-plastic finite element(FE)model of power spinning of thin-walled aluminum alloy shell with hoop inner rib was established under software ABAQUS.Key technologies were dealt with reasonably.The reliability of the FE model was verified theoretically and experimentally.The forming process was simulated and studied.The distribution of the thickness and stress,and the variations of spinning force were obtained.The workpiece springback was analyzed with ABAQUS/Standard.The results show that the FE model considering elastic deformation can not only be used to analyze the workpiece springback in the complex spinning process,but also serve as a significant guide to study the local deformation mechanism and choose the reasonable parameters.
文摘Discusses the elastic deformation of ellipsoidal shell of different axis ratio under inner pressure during hydraulic bulging forming with theoretical results in good agreement with actual result, thereby providing theoretical basis for hydraulic bulging forming of ellipsoidal shell.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB832902)the National Natural Science Foundation of China(Grant Nos.11275241,11205225,11105192,and 11275238)
文摘Fe K-shell ionization cross sections induced by 2.4-6.0 MeV Xe^20＋ are measured and compared with different binary- encounter-approximation （BEA） models. The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge （Zeff） agrees well with the experimental data. Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states （20＋, 22＋, 26＋, 30＋） verifies the applicability of the effective nuclear charge （Zeff） correction for the BEA model. It is found that Zeff correction is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies. However, when the M shell is opened, the Zeff corrected BEA model is unable to explain the inner-shell ionization, and the electron transfer by molecular-orbital promotion should be considered.
