The Nanoindentation is a precise technique for the elucidation of mechanical properties. But such elucidation requires physically based interpretation of the loading curves that is widely still not practiced. The use ...The Nanoindentation is a precise technique for the elucidation of mechanical properties. But such elucidation requires physically based interpretation of the loading curves that is widely still not practiced. The use of indentation hardness <em>H</em> and indentation modulus <em>E<sub>r</sub></em> is unphysical and cannot detect the most important phase-transitions under load that very often occur. The claim that <em>H </em>versus<em> E </em>plots relate linearly for all different materials is neither empirically found nor correctly deduced. It is most dangerous by producing incorrect materials properties and misleading. The use of <em>H/E</em> (that is also called “elasticity index”) in complicated formulas for brittle parameter, yield strength, toughness, and so-called “true hardness” is also in error. The use of<em> H/E </em>cannot reveal the true qualities of materials without considering phase-transitions under load that require the correct exponent 3/2 on <em>h</em> for the loading curves (instead of disproved 2). This is exemplified with the physical data of different mollusk shells that experience phase-transitions, a new bionics model, and different contributions for their strengthening. The data are compared to the ones of aragonite and calcite and vaterite.展开更多
Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationshi...Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.展开更多
文摘The Nanoindentation is a precise technique for the elucidation of mechanical properties. But such elucidation requires physically based interpretation of the loading curves that is widely still not practiced. The use of indentation hardness <em>H</em> and indentation modulus <em>E<sub>r</sub></em> is unphysical and cannot detect the most important phase-transitions under load that very often occur. The claim that <em>H </em>versus<em> E </em>plots relate linearly for all different materials is neither empirically found nor correctly deduced. It is most dangerous by producing incorrect materials properties and misleading. The use of <em>H/E</em> (that is also called “elasticity index”) in complicated formulas for brittle parameter, yield strength, toughness, and so-called “true hardness” is also in error. The use of<em> H/E </em>cannot reveal the true qualities of materials without considering phase-transitions under load that require the correct exponent 3/2 on <em>h</em> for the loading curves (instead of disproved 2). This is exemplified with the physical data of different mollusk shells that experience phase-transitions, a new bionics model, and different contributions for their strengthening. The data are compared to the ones of aragonite and calcite and vaterite.
基金financially supported by the National Natural Science Foundation of China (41130640, 91425301, 41321001, 41401057)the projects from the State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University
文摘Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.
