Mineralogy of the deep lower mantle in the presence of H2O

Understanding the mineralogy of the Earth''s interior is a prerequisite for unravelling the evolution and dynamics of our planet. Here, we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle (DLM, 1800–2890 km in depth) and observed surprising mineralogical transformations in the presence of water. Ferropericlase, (Mg, Fe)O, which is the most abundant oxide mineral in Earth, reacts with H₂O to form a previously unknown (Mg, Fe)O₂H_x (x ≤ 1) phase. The (Mg, Fe)O₂H_x has a pyrite structure and it coexists with the dominant silicate phases, bridgmanite and post-perovskite. Depending on Mg content and geotherm temperatures, the transformation may occur at 1800 km for (Mg_0.6Fe_0.4)O or beyond 2300 km for (Mg_0.7Fe_0.3)O. The (Mg, Fe)O₂H_x is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences (Mg²⁺, Fe³⁺ and H⁺). This important phase has a number of far-reaching implications including extreme redox inhomogeneity, deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere.     

档案开放利用情况的数据分析——档案充分利用问题研究之二

本文通过可靠的统计数据详细地分析了档案馆和档案室的档案开放情况,阐述了档案开放对于档案充分利用的意义,并提醒人们在关注档案馆开放档案问题的同时,应该对档案室的档案开放问题给予必要的关注.     

档案已供利用情况的数据分析——档案充分利用问题研究之三

本文通过可靠的统计数据分别详细地分析了档案馆和档案室档案已供利用情况,针对档案利用率低的事实,提出要根据档案馆和档案室的不同情况来充分利用已有档案和提高档案利用率的方向性要求.     

关于高校学术权力弱化问题的思考

学术是大学的本质之所在;自由是学术的基本要求.学术权力来源于学者对某一学科知识领域的专长,它是大学的生命力.当今大学学术权力呈现日益弱化的趋势,强化学术权力,提高大学的学术气氛,时深化大学改革,促进大学发展,实现世界一流大学的梦想有很大的现实意义.     

学校心理咨询若干理论问题探讨

学校心理咨询作为一种现代意义上的助人职业活动,在我国已经走过了20余个春秋.但到目前为止,学校心理咨询的一些基本理论问题并没有得到深入研究,这就在一定程度上影响到这门学科的专业化发展.本文拟围绕学校心理咨询的界定、学校心理咨询的任务、学校心理咨询的学科性质、学校心理咨询与相关领域的关系、学校心理咨询的意义等几个基本理论问题提出自己的看法,以期为这门学科的基本理论建设尽绵薄之力.     

民办本科院校发展的困境及对策

民办高等教育是伴随我国高等教育大众化的过程而逐渐发展起来的,其成长于高等教育供不应求的历史背景.在其发展过程中,未能建立起足够的品牌吸引力与公办本科院校进行竞争.随着高等教育供求逐渐平衡和供大于求转变,民办本科院校陷入困境.为求脱困,民办本科院校应立足其资源,定位于应用型本科教育,拓展校企合作深度,并扎根于市场,构建出...     

英国城市学院发展轨迹偏离之分析

城市学院的产生是英国高等教育近代化的主要标志,它顺应了英国工业化的要求,代表了新型大学的发展方向。然而由于经济、政治、文化以及城市学院自身因素的影响,城市学院在发展过程中偏离了原先的轨迹,出现了向传统大学靠拢与回归的现象。我国高职院校有着与英国的城市学院极为相似的社会背景,其发展过程中也出现了轨迹偏离现象。因此,分析英国城市学院发展轨迹对我国高职院校的健康发展有着极大的借鉴意义。     

研究型大学本科教学质量监控体系构建与探索

文中基于可持续发展的质量观及现代质量管理的思想与技术,构建适应研究型大学特点的本科教学质量监控理论与方法体系;并从教学质量标准的策划、教学输入环节的预防性控制、教学实施过程的多维度监测、教学输出环节的目标管理、教学评价信息的反馈与教学工作改进等方面入手,探讨研究型大学教学质量监控实践策略,促进精英型人才的培养。     

New physics searches at the BESIII experiment

The standard model (SM) of particle physics, comprised of the unified electroweak and quantum chromodynamic theories, accurately explains almost all experimental results related to the micro-world, and has made a number of predictions for previously unseen particles, most notably the Higgs scalar boson, that were subsequently discovered. As a result, the SM is currently universally accepted as the theory of the fundamental particles and their interactions. However, in spite of its numerous successes, the SM has a number of apparent shortcomings, including: many free parameters that must be supplied by experimental measurements; no mechanism to produce the dominance of matter over antimatter in the universe; and no explanations for gravity, the dark matter in the universe, neutrino masses, the number of particle generations, etc. Because of these shortcomings, there is considerable incentive to search for evidence for new, non-SM physics phenomena that might provide important clues about what a new, beyond the SM theory (BSM) might look like. Although the center-of-mass energies that BESIII can access are far below the energy frontier, searches for new, BSM physics are an important component of its research program. This report reviews some of the highlights from BESIII’s searches for signs of new, BSM physics by: measuring rates for processes that the SM predicts to be forbidden or very rare; searching for non-SM particles such as dark photons; performing precision tests of SM predictions; and looking for violations of the discrete symmetries C and CP in processes for which the SM expectations are immeasurably small.     

《中国分类主题词表》的两种对应依据

兼容型词表包括字面对应、概念对应和虚拟对应3种形式.<中国分类主题词表>的对应方式为侧重理论分析的基于类目涵义的一体化对应方式和侧重实践应用的基于文献标引的一体化对应方式.我国兼容词表的对应方式将会逐渐过渡到以基于文献标引为主的对应方式.参考文献9.