细度和染色杂质对方解石白度的影响

方解石经超细粉碎后通过水力分级分成若干粒级；考察细度对方解石白度的影响；运用高梯度强磁选考察弱磁性染色杂质对方解石白度的影响。     

Burning issues: Whiteness, rurality and the politics of difference

In the past decade geographers have critiqued the exclusivity of idyllic representations of rurality and sought to explore the diverse experiences of Other social groups in the countryside. This paper builds upon that small but significant strand of research which has highlighted the whiteness of representations of rurality and the consequences of this for racialised minorities. These debates have been crucially important in forwarding our understanding of racially-exclusive constructions of idyllic country living; however, it is important that academics neither assume that such ideas are forever fixed, nor that they affect all minority ethnic groups in the same ways. This paper takes both the potential power and frailty of these ideas seriously, as it examines how the concepts of race, racism and rurality are deployed by different commentators as they debate the place of one specific minority ethnic group in the English countryside. The route taken into this is a consideration of print-media reporting of events in Firle, Sussex, where, in 2003, some white rural residents symbolically purged their village of Gypsy-Travellers by burning a mock caravan complete with effigies at their annual bonfire celebrations. In conclusion, the paper challenges the relative lack of attention to these issues within the white-dominated discipline of geography, and argues that it is imperative to trace the dynamic ways in which the whiteness of idyllic understandings of the rural are reinforced and challenged through contemporary social practice.     

矿物白度的影响因素与增白机理研究

白度是矿物的重要光学性质之一。为了深化矿物的光学性质及白色矿物功能材料的研究与应用,根据测试分析结果和叶大年的结构光性矿物学理论,系统研究了影响矿物白度的主要因素,以及矿物增白效果的差异性及其产生机理。研究结果表明:(1)晶体化学是决定不同种类透明矿物白度的最主要因素,但对于某种透明矿物来说,影响其白度的主要因素是矿物中的碳质有机质、含铁钛矿物杂质、杂质元素的价态与晶体化学环境、介质环境、矿物中的水和粒度大小等。(2)证明了透明矿物白度大小与折射率呈正相关。白度相同的不同矿物的增白效果存在很大差异性,其根本原因是由矿物折射率所决定的反射率存在很大差别。(3)提出了真白度和假白度的概念,即主要由自色产生的白度称为真白度,主要由假色产生的白度称为假白度;真白度高的矿物具有增白作用,而真白度低的矿物,即使粉末白度高,也没有增白作用。(4)在影响矿物白度的主要因素中,矿物中的碳质有机质、含铁钛矿物杂质、杂质元素的价态等杂质成分对矿物白度和增白效果起负面作用。(5)矿物中与晶体结构相关的水所产生的颜色属于自色,脱去结晶水、层间水和结构水都有利于提高矿物的真白度或增白效果,但脱去沸石水的效果正好相反;由矿物粒度大小变化产生的颜色属于假色;通过降低粉体粒度大小所提高的白度属于假白度,由此增加的白度没有增白作用。另外,矿物粉体与使用介质之间的折射率大小差别越大,增白效果越明显。     

Whiteness, space and alternative food practice

The paper demonstrates how whiteness is produced in progressive non-profit efforts to promote sustainable farming and food security in the US. I explore whiteness by addressing the spatial dimensions of this food politics. I draw on feminist and materialist theories of nature, space and difference as well as research conducted between 2003 and the present. Whiteness emerges spatially in efforts to increase food access, support farmers and provide organic food to consumers. It clusters and expands through resource allocation to particular organizations and programs and through participation in non-profit conferences. Community food’s discourse builds on a late-modern and, in practice, ‘white’ combination of science and ideology concerning healthful food and healthy bodies. Whiteness in alternative food efforts rests, as well, on inequalities of wealth that serve both to enable different food economies and to separate people by their ability to consume. It is latent in the support of romanticized notions of community, but also in the more active support for coalition-building across social differences. These well-intentioned food practices reveal both the transformative potential of progressive whiteness and its capacity to become exclusionary in spite of itself. Whiteness coheres precisely, therefore, in the act of ‘doing good’.     

‘Making space’ in Cairo: Expatriate movements and spatial practices

This paper examines what it means to be an ‘expatriate’ in Cairo through the lens of movement and space-making. Inquiring into a set of migrant (im)mobilities, spatial practices, relations, and imaginations, it argues that as a ‘spatialised’ identity category ‘expatriate’ narrates and enacts migratory privileges linked to wider hierarchies of social difference. It contributes to a growing literature examining the social and political dimensions of ‘expatriate’ migration and further engages scholarship thinking space and movement in relational and socio-historical terms. Rather than denoting an easily distinguishable group of migrants, ‘expatriate’ emerged as a contingent and ambiguous category of practice. As such, ‘expatriate’ stands in a productive relationship with privileged movement and socio-spatial processes. Like other migrants, respondents skillfully navigated the global differences in wealth, power and status they were presented with. Yet, unlike many other migrants, they did so from a privileged position within the global power-geometries of international migration. Migrants’ personal geographies were further shaped by how bodies were racialised and gendered in entangled, intersecting and sometimes counter-intuitive ways. This diversity and complexity of ‘expatriate’ geographies highlights the necessity of intersectional and situated analyses of privilege.     

浅谈粉碎洗涤盐生产中的技术改造

对粉碎洗涤盐的技改过程、技改方向进行了总结并列举大量实验数据 ,说明技改前后粉洗盐质量变化及成功经验。同时对粉洗盐粒度存在的问题进行了分析并提出建议     

Producing/contesting whiteness: rebellion, anti-slavery and enslavement in Barbados, 1816

The increasing attention paid by geographers to white identities represents a welcome corrective to research on race and ethnicity that focused on non-white subjectivities and promises to deconstruct the purportedly `normal' or `unremarkable' status often afforded to whiteness. Such work is a vital part of a critical geographical agenda. This paper seeks to contribute to such an agenda by responding to Bonnett [Area 29 (1997) 193, White Identities: Historical and International Perspectives, Prentice Hall, 2000] call for a historical geographical engagement with `white studies'. To do so, it begins by considering how such a critical geography might be spatially and theoretically framed. It then introduces a specific context for such an engagement--the revolt of 1816 by enslaved people of African origin in the British Caribbean colony of Barbados. Reading this not as a single event but as a locus of multiple and conflicting narrations, each linked to particular assertions and contestations of whiteness, the paper argues that geographies of white identities must emphasise struggles between `white' subjects, as well as the role of subaltern acts and representations in white racialisation. This is important if postcolonial, and therefore critical, geographies of white identities are to be produced.