Phase‐field modeling of epitaxial growth of polycrystalline quartz veins in hydrothermal experiments

Mineral precipitation in an open fracture plays a crucial role in the evolution of fracture permeability in rocks, and the microstructural development and precipitation rates are closely linked to fluid composition, the kind of host rock as well as temperature and pressure. In this study, we develop a continuum thermodynamic model to understand polycrystalline growth of quartz aggregates from the rock surface. The adapted multiphase‐field model takes into consideration both the absolute growth rate as a function of the driving force of the reaction (free energy differences between solid and liquid phases), and the equilibrium crystal shape (Wulff shape). In addition, we realize the anisotropic shape of the quartz crystal by introducing relative growth rates of the facets. The missing parameters of the model, including surface energy and relative growth rates, are determined by detailed analysis of the crystal shapes and crystallographic orientation of polycrystalline quartz aggregates in veins synthesized in previous hydrothermal experiments. The growth simulations were carried out for a single crystal and for grain aggregates from a rock surface. The single crystal simulation reveals the importance of crystal facetting on the growth rate; for example, growth velocity in the c‐axis direction drops by a factor of ~9 when the faceting is complete. The textures produced by the polycrystal simulations are similar to those observed in the hydrothermal experiments, including the number of surviving grains and crystallographic preferred orientations as a function of the distance from the rock wall. Our model and the methods to define its parameters provide a basis for further investigation of fracture sealing under varying conditions.     

Exploring the potential linkages between oil‐field brine reinjection,crystalline basement permeability,and triggered seismicity for the Dagger Draw Oil field,southeastern New Mexico,USA, using hydrologic modeling

We used hydrologic models to explore the potential linkages between oil‐field brine reinjection and increases in earthquake frequency (up to M_d 3.26) in southeastern New Mexico and to assess different injection management scenarios aimed at reducing the risk of triggered seismicity. Our analysis focuses on saline water reinjection into the basal Ellenburger Group beneath the Dagger Draw Oil field, Permian Basin. Increased seismic frequency (>M_d 2) began in 2001, 5 years after peak injection, at an average depth of 11 km within the basement 15 km to the west of the reinjection wells. We considered several scenarios including assigning an effective or bulk permeability value to the crystalline basement, including a conductive fault zone surrounded by tighter crystalline basement rocks, and allowing permeability to decay with depth. We initially adopted a 7 m (0.07 MPa) head increase as the threshold for triggered seismicity. Only two scenarios produced excess heads of 7m five years after peak injection. In the first, a hydraulic diffusivity of 0.1 m² s^?1 was assigned to the crystalline basement. In the second, a hydraulic diffusivity of 0.3 m² s^?1 was assigned to a conductive fault zone. If we had considered a wider range of threshold excess heads to be between 1 and 60 m, then the range of acceptable hydraulic diffusivities would have increased (between 0.1–0.01 m² s^?1 and 1–0.1 m² s^?1 for the bulk and fault zone scenarios, respectively). A permeability–depth decay model would have also satisfied the 5‐year time lag criterion. We also tested several injection management scenarios including redistributing injection volumes between various wells and lowering the total volume of injected fluids. Scenarios that reduced computed excess heads by over 50% within the crystalline basement resulted from reducing the total volume of reinjected fluids by a factor of 2 or more.     

安徽省图书馆藏《正德三年进士登科录》的修复

2013年初,为配合古籍数字化,安徽省图书馆开始修复馆藏《正德三年进士登科录》。通过分析破损现状、查找相关资料、咨询修复专家、制订修复方案、选配纸张、清洗书页、修补书页、书皮及托纸、修整书页、装订书册、残片修复与函套制作、完善修复记录,经精心修复,修复质量合格、效果满意。论文着重探讨了"古籍修复需要讲究依据"、灵活运用"修旧如旧"原则、保留修复资料等相关问题。此修复研究可为行业修复此类古籍提供相关借鉴。     

中原先秦丧葬制度中的茔域与方位之制

在先秦时期的中原,基地、墓葬的头向以及夫妻合葬墓中左右方位的选择,不断被赋予礼制的内涵,体现了我国古代丧葬制度不断发展、演变的过程。尤其是到周代,丧葬制度趋于完备。其中的茔域与方位之制,成为古代礼制的重要组成部分。     

一个外国人心目中的陈云

1935年遵义会议后,陈云帮助中共与共产国际保持着良好关系。在延安,他建立起 一套人事制度,培养了党内的一批青年知识分子。在东北,第二次世界大战后他在小城市和农村建 立了共产党的根据地,对赢得东北的军事胜利发挥了重大作用。1949-1952年,他主持恢复了国 民经济秩序。1953-1957年,他成功地制定和执行了第一个五年计划,从事建设和工业发展。尽 管他作了努力,但仍未能阻止"大跃进",但是当毛泽东给他施展才能的机会时,他使国家从严重 的政策错误中恢复过来。1978年后,他的谨慎与专长使改革置于坚实的基础之上,他致力于平反 干部的冤假错案从而有助于改革开放的成功。陈云受到很多党员的爱戴,这不仅是因为他的巨大成 就,而且是因为他对国家和党的鞠躬尽瘁的精神和无限忠诚,对其他党员的真诚和爱护以及他朴素 谦逊的生活作风。     

多维视角下的近代安徽族田分布

本文从祠堂数量、捐献族田人数以及土改调查的族田量分别对近代安徽族田的分布状况进行考察,在综合比较的基础上,勾画出近代安徽族田分布呈现自南部徽州山区向淮北平原地区递减的总体态势及其起伏.     

Queerly situated? Exploring negotiations of trans queer subjectivities at work and within community spaces in the UK

While traditional perspectives on transgender from some strands of feminism and within medical/psychoanalytical discourse have argued that transgender people conform to and reproduce gender stereotypes, queer theory has celebrated transgender as a site that highlights the social and cultural construction of ‘sex’ and ‘gender’ and, moreover, as a symbol of transgressive gender possibility. Both of these readings ignore the complexities of lived trans experiences and identifications. By evaluating a queer reading of trans through recent empirical research into transgender identities, I suggest that while trans identifications certainly queer binary models of ‘sex’ and ‘gender’, such transgressions are materially, culturally, socially and spatially contingent. The article draws on empirical research to explore the ways in which access to queer subjectivities is constrained by, and negotiated alongside, the locales of the workplace and community spaces.     

试析党的干部选拔任用标准的历史流变

德才兼备是我们党始终坚持的选拔任用干部的一个总的原则和基本标准。从毛泽东提出＂德才兼备、又红又专＂到胡锦涛明确提出＂德才兼备、以德为先＂,党的几代领导人对干部选拔任用标准的探索经历了在表述形式和具体内容上的发展演变过程。党的几代领导人关于德才兼备标准的基本＂内核＂是相同的,即要求干部必须德才兼备;而区别就在于＂德＂与＂才＂在具体内容上的不断丰富和发展。     

海归的适应策略研究：学院派的案例分析

文章在对部分海归”学院派”深入访谈和个案分析的基础上,运用布迪厄“文化资本理论”、“习性”和“场域”的分析工具,解析了海归“学院派”归国后的不同心态和不同适应策略的选择。得出结论,“文化资本”本身并不足以成为个体适应策略选择的决定因素,“习性”和“场域”概念也是影响个体适应策略选择的因素之一;深层文化认同的非同一性、生活表象与意识深层的非和谐性等复杂的文化意识构成他们独特的行为表象。这些行为表象是其长期海外生活学习所形成的个人“习性”的体现。透过这些表象了解他们的“习性”及其产生的原因,是深入了解他们归国后所选择适应策略的基础。     

近代安徽族田经营研究

在近代安徽,就族田的田产经营而言,出租给外姓中、贫农耕种是主要经营方式;地租形态主要是实物地租,且租率较一般私田低;大部分欠租是在催缴过程中通过协商解决.就族田的地租经营而言,宗族通过放贷、购田和投资工商业实现地租的增值;宗族放贷地租的利率大大低于一般私人放贷;族田地租向近代工商业转化已渐露端倪.