聚醋酸乙烯酯乳液的表征、性能及其在彩绘类文物保护中的应用

聚醋酸乙烯酯(PVAc)乳液是常见的彩绘类文物保护材料。采用激光粒度仪、热重/差热分析、红外光谱、X-射线衍射、扫描电镜、透射电镜等表征了PVAc乳液的粒径以及胶膜的热稳定性、结构和形貌;采用粘度计、表面张力仪、pH计、电导率仪等研究了乳液浓度与其粘度、表面张力、pH、电导率的关系;通过冻融、室温-高温放置、离心分离研究了乳液的稳定性;同时用PVAc乳液对模拟起甲和酥碱的壁画进行了修复。结果表明,PVAc乳液粒径呈双峰分布,小粒子的平均粒径为380 nm,大粒子的平均粒径为5.85μm;乳液胶膜为非结晶物质,胶膜热重的最终质量残留为1.54%,335℃出现放热峰。PVAc乳液的电导率随浓度的增大而增大,pH随浓度的增大而下降;相同温度下表面张力随浓度的增大而基本呈现低浓度下降,高浓度上升的趋势。相同浓度下,表面张力随温度升高而无显著变化,表明PVAc乳液的表面张力受温度变化影响不大。相同温度下,乳液粘度随浓度的增大而增大;相同浓度下,乳液的粘度随温度的升高而降低。冻融、离心分离和不同温度下静置发现,该乳液出现分层。用该乳液对模拟起甲和酥碱壁画修复后,再分别老化20个循环和12个循环,发现颜料层再次空鼓、起甲。综合分析,说明实验中所使用的该种PVAc稳定性和抗老化能力较弱,在修复彩绘类文物中应慎重选择PVAc的种类,综合考虑PVAc的使用浓度、环境因素对其性能的影响,以达到最佳使用效果。     

The impacts of parental migration on children’s subjective well-being in rural china: a double-edged sword

ABSTRACT

The emerging problem of left-behind children has attracted mounting academic and policy attention. Prior studies primarily cast light on left-behind children’s education, health, and behavior, while their subjective well-being is much less understood yet. Based on a nationally representative sample of rural children aged 10–15 in 2014, we examine the impacts of different types of parental migration on children’s subjective well-being and how these affects vary between boys and girls. The results show that parental migration is a double-edged sword: children from both-parent migrant families report compromised life satisfaction and relationship quality compared with those in integral families, and mother-only migration significantly lowers children’s subjective health. On the flip side, father-only migration enhances children’s aspiration for attaining college, an encouraging effect that is even stronger than that of parental education and family income. These effects are heterogeneous by children’s gender: boys seem to be more susceptible to the disruptive effects of both-parent migration; mother-only migration effectively promotes girls’ educational aspiration while father-only migration promotes boys’. This study portrays a comprehensive image of left-behind children. Relaxation of hukou restriction, equal access to education, and revitalization of rural economies are imperative to improve the well-being of left-behind children.

Abbreviations: LBC: Left-behing children; SWB: subjective well-being     

《里耶秦简》(壹)所见作徒管理问题探讨

秦代编制作徒簿的机构有授予方的司空和仓,但二者分工不同;接收方包括库、田官、畜官、少内、属乡等。作徒簿分为临时付受与月度统计两种。秦代各级地方机构对刑徒管理的分工为:郡提出指导原则,县掌握本县刑徒的数据,县属机构负责具体管理。在当时人的观念中,徒隶是一个阶层的泛称,但在司法行政文书中则有特定的内涵,司寇不包括在内。     

云神:"夸父"神话叙事本源

一、《山海经》:"夸父"神话叙事源头 说到"夸父",我们立即想到"夸父逐日"神话."夸父逐日"神话见于《山海经·海外北经》、《山海经·大荒北经》与《列子·汤问》、《博物志·史补》.     

从地方志的考察中看明清人的奢靡观

本文以地方志为基本资料进行考察,认为传统意义上广义的奢靡观念可以从以下几个方面界定:1.某事项的花费超过该事项的基本需要;2.某些不正当不应有的消费项目与活动;3.某消费与个人(或部分人)的收入不相称;4.消费者攀比浮夸。奢靡观念的新旧激荡反映出明清社会的变迁及其局限性。     

新冠疫情下的博物馆:困境与对策

目前依然在全球肆虐的新冠疫情深刻影响着博物馆的当下与未来.纵观欧美各大博物馆,短期来看,疫情导致的闭馆直接引发了系列财务、减员等问题,而包括系统性歧视的平权运动在内的各类全新的社会议题同样亟待博物馆关注;长期来看,在疫情这场"持久战"面前,博物馆面临着应急、恢复、提升等三方面困境,以及将困境转变为机遇的挑战.为此,加拿...     

Mississippian monumentality in the Yazoo Basin: recent investigations at the Carson site (22CO505), northwestern Mississippi

Investigations at the Carson site (22CO505), located in Coahoma County, Mississippi, have uncovered data on the development of a large Mississippian mound center dating to the period from A.D. 1200 through European contact. Recent sediment coring, excavation, artifact analyses, and radiocarbon and optically stimulated luminescence (OSL) dating shed light on earthworks and household structures at Carson, and on Mississippian culture in the Yazoo Basin more generally. Sediment coring demonstrates a laterally transgressing Mississippi River system deposited coarse sandy ridges and clay-filled swales underneath a surface horizon comprised of variously coarse to medium-fine sediment originating from generalized overbank flooding. In some instances, flood-borne sediments were found on mound flanks, indicating that at times river-based flooding may have interrupted mound construction. Sediment coring and trench excavation also demonstrate that Carson’s Mound D was built in four stages, with Stages II and III comprising the major stages of earth moving. Excavations on the mound summit reveal evidence of several superimposed structures that were burned in place and likely used for the production of stone, shell, and wooden craft items, perhaps related to Mississippi Ideational Interaction Sphere (MIIS) paraphernalia. Here we describe recent investigations at Carson and present preliminary findings; forthcoming publications will emphasize strategies of power, monumentality, craft production, and Mississippian exchange systems.     

工业革命定义之争

一百多年来,史学界和经济学界对工业革命进行了深入研究,但究竟什么是工业革命往往人言人殊.学者们就历史上是否存在工业革命争论不休,即使承认工业革命是一场经济大变革的学者,也开展了渐进论和突变论的争论.罗斯托、门德尔斯、德弗里斯等学者提出了起飞、原工业化、勤劳革命等概念.国内外学者把工业革命定义的研究分为社会变革学派、工业组织学派、宏观经济学派、技术学派、能源学派和消费学派,博采众长者亦有之,这些研究从不同侧面抓住工业革命的特征.这些成为后来工业革命研究的起点.     

明代后金女真"沈"姓探--从《明代满蒙史料·李朝实录抄》"沈"姓记载看女真姓氏的变化

“沈”姓满洲族的老姓说法不一,“老姓”中没有“沈”字,还有朝鲜族沈姓和“沈氏”汉军八旗融入满洲族。事实上,辽金女真有“沈”的姓氏即“沈谷”,尽管可能是音译,但是其他姓氏如“童”也存在,《明代满蒙史料.李朝实录抄》记载后金女真有大量汉姓“沈”和女真名字者的记录。因为民族生存战争、土地的争夺与保卫,因为女真族、满洲族颠沛流离的生活环境和历史,因为没有相应的文化建设,一般女真族没有连续家谱的记录,女真到满洲的姓氏从来不连续,满洲族的家谱绝大多数的撰写始于多尔衮进关。从“沈”姓在后金女真中存在的举证,往前到辽金时代、往后到清代,“沈”姓都是以不同表现形式存在着,说明从辽金女真、后金女真、以及到辛亥革命前后满洲族都有“沈”姓氏,和这个族群一样,“沈”姓氏是变化演绎的,女真到满洲族姓氏同样是变化演绎的。     

日本新感觉派及其对中国文学的影响

日本新感觉派形成于20世纪20年代中期,强调主观感觉在创作中的重要作用。它诞生之初,就在日本文坛掀起轩然大波,论争主要围绕新感觉派的创作方法展开。日本新感觉派对中国文学创作产生过两次影响,第一次是20年代末30年代初,以刘呐鸥、穆时英、施蛰存为代表的新感觉派小说,他们较多从文体和创作技法上吸收;第二次是80年代贾平凹、莫言和余华等人的创作,巧妙汲取日本新感觉派的风韵,化入到作品肌髓。