氢氘交换用于古代皮革胶原蛋白微观结构的研究

皮革文物由动物皮制作而成,是人类在认识和改造自然过程中留下的宝贵财富,是研究古代社会历史的珍贵实物史料。皮革作为一种天然有机高分子材料,其主要组成成分胶原蛋白易受保存环境影响发生变性劣化,研究胶原蛋白的微观结构对于了解古代皮革的劣化具有非常重要的意义。氢氘交换技术(HDX)基于蛋白质中不稳定的氢原子会与氘原子发生交换的原理常被用于蛋白质结构研究,但其用于古代皮革胶原蛋白的结构研究却鲜见报道。本研究采用HDX结合傅里叶变换红外光谱技术(FTIR),对现代皮革、人工老化皮革和古代皮革胶原蛋白的三股螺旋结构进行了分析和比较研究,通过特征吸收峰的位置和氘代率来表征胶原蛋白微观结构的变化。研究结果表明现代皮革胶原蛋白的三股螺旋结构保存完整,氘原子难以进入其中与主链氨基氢原子发生交换反应,氘代率为32.09%。而人工老化皮革和古代皮革在劣化过程中胶原蛋白主链酰胺氢的溶剂可及性以及其参与形成的氢键发生了变化,维系三螺旋结构稳定的氢键断裂,三股螺旋结构发生一定程度解体,位于螺旋结构中心的甘氨酸暴露出来,增大了骨架酰胺氢的溶剂可及性,结构变得松散不稳定,加快了氢氘交换速率,更容易发生氢氘交换反应。三个古代皮革样品中Old3的氘代率最低,氘代率为65.87%,其三股螺旋结构被破坏程度最小,劣化程度也最轻。与之前已报道的氢氘交换研究蛋白质结构的文献相比,在以下方面做出拓展:一是通过分析胶原蛋白特征结构,指出主链氨基氢尤其是甘氨酸的酰胺氢是与氘原子发生交换的主要对象。二是根据氢氘交换后相应基团质量数发生变化会引起伸缩振动频率的变化这一特点,选择傅里叶变换红外光谱中胶原蛋白的酰胺A带来作为氢氘交换反应的表征工具,通过特征峰的位置和氘代率来量化氢氘交换程度。本研究将氢氘交换技术与傅里叶变换红外光谱技术相结合,引入到皮革文物胶原蛋白结构的研究中,有助于深刻理解皮革文物劣化机理,为胶原蛋白微观结构的研究和皮革文物劣化程度分析提供了一种新的方法和研究思路。     

Human Security as ontological security: a post-colonial approach

ABSTRACT

This article will critically interrogate the relationship between Human Security and Ontological Security from a broadly postcolonial perspective. The dislocation engendered by successive waves of neo-liberal globalisation has resulted in the deracination of many of the world's inhabitants, resulting in a state of collective ‘existential anxiety’ [Anthony Giddens, Modernity and Self-Identity: Self and Society in the Late Modern Age, Cambridge: Polity Press, 1991]. Under such conditions, the search for ontological security becomes paramount. However, conventional understandings of Human Security as ‘freedom from fear and want’ are unable – from a post-colonial perspective – to provide ontological security since they operate within a culturally specific, Eurocentric understanding of the ‘human’ as ‘bare life’ [Giorgio Agamben, Homo Sacer: Sovereign Power and Bare Life, Daniel Heller-Roazen (trans), Stanford, CA: Stanford University Press, 1998]. It will then be argued that post-secular conceptions of Human Security [Giorgio Shani, Religion, Identity and Human Security, London and New York: Routledge, 2014] by acknowledging the role which culture and religion can play in providing answers to existential questions concerning the ‘basic parameters of human life’ are better able to ‘protect’ ontological security in times of rapid global transformation given the centrality of religion to post-colonial subjectivity. This will be illustrated by the case of the global Sikh community. It will be argued that ontological, and therefore, Human Security rests on reintegrating the ‘secular’ and ‘temporal’ dimensions of Sikhi, which had been severed as a result of the colonial encounter.     

Family and Sexuality the American Way

Books reviewed in this article: Karen Dubinsky, The Second Greatest Disappointment: Honeymooning and Tourism at Niagara Falls Kathleen Anne McHugh, American Domesticity: From How‐to Manual to Hollywood Melodrama Leila J. Rupp, A Desired Past: A Short History of Same‐Sex Love in America John C. Spurlock and Cynthia A. Magistro, New and Improved: The Transformation of American Women's Emotional Culture Jessica Weiss, To Have and To Hold: Marriage, the Baby Boom and Social Change